Photoinitiators

Abstract

Latent photoinitiator compounds and compositions containing such compounds, as well as their use in photoinitiation methods for producing structured photoresists, are described.

Description

[Technical field]

[0001] The present invention relates to substituted thioxanthone derivatives in which the carbonyl group is blocked by an acyclic ketal or a substituted or unsubstituted 1,3-dioxolane group, or a substituted or unsubstituted 1,3-dioxane group, or a substituted or unsubstituted 1,3-dioxepane group, or a substituted or unsubstituted 1,3-dioxocane group, or a substituted or unsubstituted 1,3-dioxonane group, and the use of such derivatives in photoinitiated reactions. The present invention also relates to synthetic methods for producing these and other substituted thioxanthone derivatives. [Background technology]

[0002] Light-absorbing ketone compounds are well known for use in light-induced reactions. These species are commonly called photoinitiators or photosensitizers, which generate reactive species upon exposure to radiation. Examples of such photoinitiators or photosensitizers can be found in U.S. Pat. No. 7,585,611B, EP 2,792,694 A1, and U.S. Pat. No. 7,425,585B. When incorporated into a suitable chemically convertible substrate, the reactive species generated by exposure to radiation, optionally in combination with other species, can directly or indirectly cause a chemical reaction in said chemically convertible substrate via sensitization and energy or electron transfer processes. Typically, said chemically convertible substrate comprises an organic material, which can be a monomer, oligomer, polymer, or mixtures thereof, that is converted into a new polymeric material.

[0003] In some applications, it is desirable to block the ketone moiety or portions of the ketone photoinitiator so that the photoinitiator is latent and can be activated by deblocking. US2004 / 0014833 and WO2011 / 086389 relate to such protected ketone photoinitiators and methods of using them.

[0004] The present invention relates to blocked or latent ketone photoinitiators that are improved over those known in the art. In particular, the blocked or latent ketone photoinitiators of the present invention, which have specific substituents and / or protecting groups on the thioxanthone carbon backbone, have been found to have properties that make them desirable in a variety of applications. These properties include an increased solubility differential of at least the deprotected species in aqueous or organic development media when compared to unsubstituted photoinitiators.

[0005] Unless otherwise stated, reference herein to a "blocked" ketone photoinitiator is a reference to a latent ketone, where the ketone group is blocked by reaction of the ketone with a diol to form a 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, or 1,3-dioxonane group. As a result, reference herein to an "unblocked" or "deblocked" ketone photoinitiator is a reference to an active ketone photoinitiator having a carbonyl present in place of the 1,3-dioxolane or 1,3-dioxane or 1,3-dioxepane, 1,3-dioxocane, or 1,3-dioxonane group. Unless otherwise stated, reference herein to a "protected" ketone photoinitiator is a reference to a compound having a functional group present on the aromatic ring of the photoinitiator, where the functional group is modified by including a protecting group. For example, acetal, alkyl carbonate, and ester substituents are protecting groups for the parent hydroxy group, and thus a compound having one of these protecting groups as a substituent can be referred to as a protected ketone photoinitiator.

[0006] One particular application of the blocked ketone photoinitiators for which the compounds of the present invention are suitable is as a component of a photoresist composition. Photoresists are photosensitive compositions used in many industrial processes, with particularly important applications in the electronics industry. Typically, a photoresist composition is coated onto a substrate to form a photoresist layer. Selected areas of the layer are then exposed to electromagnetic energy, usually light energy such as UV, deep UV, KrF or ArF excimer laser light, EUV light, or electron beam (EB), to initiate a chemical reaction in the exposed areas of the photoresist. A photoresist developer is then used to remove materials that are soluble in the developer. Photoresists can take the form of negative photoresists or positive photoresists. A positive photoresist is a photoresist in which the exposed portions of the photoresist become soluble in the photoresist developer and thus can be removed by the developer, while the unexposed portions of the photoresist remain insoluble in the photoresist developer. A negative photoresist is one in which the exposed portions of the photoresist become insoluble in the photoresist developer, while the unexposed portions of the photoresist dissolve and can be removed by the photoresist developer. After the developer step, a patterned coating remains on the surface that is insoluble in the developer. Further steps can be performed to harden the coating, such as a curing step, which can be performed by application of heat or exposure to further light.

[0007] When the soluble portions of the photoresist to be removed by the developer have very fine features, which is common for positive photoresists, it is important that the species present in the areas to be removed are soluble in the developer medium, which is usually an aqueous medium. Otherwise, so-called "scumming" can occur. The latent or blocked photoinitiators described herein can be advantageously used in such photoinitiation methods. Summary of the Invention

[0008] In accordance with the present invention, there is provided a compound of formula I:

[0009] [ka]

[0010] wherein n is 1, 2, 3, 4, or 5, and one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0011] In one embodiment, one of the aromatic rings is substituted with at least one (e.g., 1, 2, 3, or 4) substituents independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, and the other aromatic ring is unsubstituted. In another embodiment, each of the aromatic rings is substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.In this embodiment, each of the rings is substituted with one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, or one of the rings is substituted with two substituents independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio and the other ring is substituted with one substituent selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, or one of the rings is substituted with hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio. , acetals, esters, oxyacetic acid and esters thereof, aryloxy, and arylthio, and the other ring is substituted with one substituent selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetals, esters, oxyacetic acid and esters thereof, aryloxy, and arylthio, or one ring is substituted with four substituents independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetals, esters, oxyacetic acid and esters thereof, aryloxy, and arylthio, and the other ring is substituted with one substituent selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetals, esters, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0012] In other embodiments, each of the aromatic rings is substituted with at least two substituents, e.g., at least three substituents, e.g., four substituents, each independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy and arylthio.

[0013] In some embodiments, the 1,3-dioxolane ring, the 1,3-dioxane ring, the 1,3-dioxepane ring, the 1,3-dioxocane ring, or the 1,3-dioxonane ring can be unsubstituted. In some embodiments, the 1,3-dioxolane ring, the 1,3-dioxane ring, the 1,3-dioxepane ring, the 1,3-dioxocane ring, or the 1,3-dioxonane ring can be substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl, or vinyl in any substitution pattern, such as geminal, vicinal, or other pattern. In some examples, (chloro)alkyl includes C1-6 (chloro)alkyl, such as (chloro)methyl, (chloro)ethyl, (chloro)propyl, and also includes (chloro)cycloalkyl, where, for example, two substituents can be introduced onto the 1,3-dioxane ring to form a cyclic group, such as a 5- or 6-membered carbocyclic ring fused to the 1,3-dioxane ring. In some examples, the 1,3-dioxolane ring, the 1,3-dioxane ring, the 1,3-dioxepane ring, the 1,3-dioxocane ring, or the 1,3-dioxonane ring can be substituted with one or more C1-6 alkyl groups, such as two or more C1-6 alkyl groups, in any substitution pattern. For example, the 1,3-dioxolane ring, the 1,3-dioxane ring, the 1,3-dioxepane ring, the 1,3-dioxocane ring, or the 1,3-dioxonane ring may be substituted with geminal or vicinal C1-6 alkyl groups, such as geminal or vicinal methyl groups. In some examples, the 1,3-dioxolane ring, the 1,3-dioxane ring, the 1,3-dioxepane ring, the 1,3-dioxocane ring, or the 1,3-dioxonane ring may be substituted with 1, 2, 3, or 4 C1-6 alkyl groups, such as 1, 2, 3, or 4 methyl groups. In all of the above examples, it will be understood that C1-6 alkyl includes methyl, ethyl, propyl, butyl, pentyl, and hexyl, and all positional isomers thereof.

[0014] In some instances, the compounds of the present invention are other than those of formula I and may be based on the same thioxantone ketone photoinitiator with a ketone blocked by an acyclic ketone, for example a compound in which the ketone is "blocked" by two alkoxy groups, for example two ethoxy groups. Such compounds have the formula:

[0015] [ka]

[0016] wherein R is methyl, ethyl, or propyl, and one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio; Particularly preferred compounds of this type include: 9,9-diethoxy-3,4-dimethoxy-thioxanthene, 2-methoxy-6,6-dipropoxy-thiochromeno[3,2-g][1,3]benzodioxole, and 6,6-diethoxy-2-methoxy-thiochromeno[2,3-e][1,3]benzodioxole.

[0017] The present invention also provides (a) a compound of formula I or Ia as defined above; and (b) a chemically transformable substrate; wherein the compound of formula I or Ia is a precursor of a reactive derivative of formula II;

[0018] [ka]

[0019] The compounds of formula II have the same substitution pattern as the compounds of formula I or Ia and can be obtained by reacting the compounds of formula I or Ia in the presence of an acid; and Additionally, the chemically convertible substrate may be converted by direct or indirect photoinitiation in the presence of a compound of formula II.

[0020] In some instances, compounds of formula II having the same substitution pattern as compounds of formula I or Ia can be obtained by reacting compounds of formula I with heat treatment in the presence of an acid.

[0021] By "reactive derivative" is meant that a ketal, e.g., an acyclic ketal such as diethyl ketal, or a cyclic ketal, such as the 1,3-dioxane or 1.3-dioxolane or 1,3-dioxepane or the 1,3-dioxocane or the 1,3-dioxonane moiety, is cleaved by treatment with acid, with or without heat, to make available a carbonyl group which provides a reactive functionality in a photoinitiated process, as described below.

[0022] The composition of the present invention comprises (a) forming a layer of said composition on a substrate; (b) applying an acid or generating an acid in situ to the predetermined areas of said layer and reacting said acid with a compound of formula I or formula Ia to form a reactive derivative of formula II in the predetermined areas of said layer; (c) exposing the layer with the reactive derivative present in the predetermined areas to electromagnetic radiation of a wavelength or energy suitable to generate a reactive species from a compound of formula II; and (d) causing said reactive species to directly or indirectly convert said chemically convertible substrate; The photoinitiated method may be used in a photoinitiated manner, including

[0023] In some embodiments, allowing the acid to react with the compound of formula I or Ia to form the reactive derivative of formula II may include the application of heat, which may be done simultaneously with the application of the acid or in situ generation of acid, or may be done after this step.

[0024] In some embodiments, the method may further include performing a post-conversion heat treatment.

[0025] The temperature of one or both of these heat treatments may range from 70° C. to 170° C. The duration of one or both of these heat treatments may range from 2 minutes to 120 minutes. It will be understood that the aforementioned temperatures and times are provided by way of example only and should not be considered limiting in any way.

[0026] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0027] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0028] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0029] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, ester, oxyacetic acid and its esters, aryloxy, and arylthio.

[0030] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0031] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid, aryloxy, and arylthio.

[0032] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, oxyacetic acid, aryloxy, and arylthio.

[0033] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, acetal, ester, oxyacetic acid, aryloxy, and arylthio.

[0034] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, ester, oxyacetic acid and its esters, aryloxy, and arylthio.

[0035] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, ester, oxyacetic acid, aryloxy, and arylthio.

[0036] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, oxyacetic acid and its esters, aryloxy, and arylthio.

[0037] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid, aryloxy, and arylthio.

[0038] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, acetal, oxyacetic acid and its esters, aryloxy, and arylthio.

[0039] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, acetal, ester, oxyacetic acid and its esters, aryloxy, and arylthio.

[0040] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, ester, oxyacetic acid and its esters, aryloxy, and arylthio.

[0041] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, acetal, oxyacetic acid and its esters, aryloxy, and arylthio.

[0042] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, oxyacetate, aryloxy, and arylthio.

[0043] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, acetal, oxyacetic acid, aryloxy, and arylthio.

[0044] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, ester, oxyacetic acid, aryloxy, and arylthio.

[0045] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0046] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, acetal, oxyacetic acid, aryloxy, and arylthio.

[0047] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, ester, oxyacetic acid, aryloxy, and arylthio.

[0048] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0049] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, acetal, ester, oxyacetic acid, aryloxy, and arylthio.

[0050] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, acetal, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0051] In some embodiments, reactive derivatives of formula II include compounds of formula II where one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0052] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, oxyacetic acid, aryloxy, and arylthio.

[0053] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, oxyacetate, aryloxy, and arylthio.

[0054] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, acetal, oxyacetic acid, aryloxy, and arylthio.

[0055] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, ester, oxyacetic acid, aryloxy, and arylthio.

[0056] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0057] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, alkylcarbonate, hydroxyalkyl, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0058] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, acetal, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0059] In some embodiments, reactive derivatives of formula II include compounds of formula II where one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0060] In some embodiments, reactive derivatives of formula II include compounds of formula II in which one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, hydroxyalkyl, oxyacetic acid, aryloxy, and arylthio.

[0061] For the avoidance of doubt, the reference in the preceding paragraph to "one or both of the aromatic rings substituted with at least one substituent independently selected from ..." refers to the situation where each of the aromatic rings is mono-substituted, di-substituted, tri-substituted, or quadruple-substituted with each substituent independently selected from any of the lists provided herein. It will be understood that the same reference applies equally to the situation where one ring has one substituent and the other has two, three, or four substituents, or where one ring has two substituents and the other has three or four substituents, in all cases with substituents independently selected from any of the lists provided herein.

[0062] In some embodiments of the present invention, the compounds of the present invention have good solubility in aqueous media and are suitable for use in photoinitiated processes in which the compounds remain after conversion of a chemically convertible substrate and must be removed by an aqueous developer.

[0063] In other embodiments, the compounds of the present invention, after deprotection, are much more soluble in aqueous media, making them suitable for use in photoinitiated processes, where the compounds themselves, particularly their deprotected forms, should survive conversion of said chemically convertible substrate and be removed by aqueous developer solutions, resulting in improved contrast and enhanced image quality after development.

[0064] 1-13 show the UV spectra of various compounds of the invention at 0.0008% in acetonitrile as follows: [Brief description of the drawings]

[0065] [Figure 1] FIG. 1 shows the UV spectrum of 2,3-dimethoxy-9H-thioxanthen-9-one. [Diagram 2] FIG. 2 shows the UV spectrum of 2,3-dihydroxy-9H-thioxanthen-9-one. [Diagram 3] FIG. 3 shows the UV spectrum of 2,3,5-trimethoxy-9H-thioxanthen-9-one. [Figure 4] FIG. 4 shows the UV spectrum of 2,3,7-trimethoxy-9H-thioxanthen-9-one. [Diagram 5] FIG. 5 shows the UV spectrum of 1,5,6-trihydroxy-9H-thioxanthen-9-one. [Figure 6] FIG. 6 shows the UV spectrum of 1,5,6-trimethoxy-9H-thioxanthen-9-one. [Figure 7] FIG. 7 shows the UV spectrum of 3,4-dihydroxy-9H-thioxanthen-9-one. [Figure 8] FIG. 8 shows the UV spectrum of 3,4-dimethoxy-9H-thioxanthen-9-one. [Figure 9] FIG. 9 shows the UV spectrum of 3',4'-dimethoxyspiro[1,3-dioxane-2,9'-thioxanthene]. [Figure 10] FIG. 10 shows the UV spectrum of 2',3'-dimethoxyspiro[(1.3)-dioxolane-2,9'-thioxanthene]. [Figure 11] FIG. 11 shows the UV spectrum of 3',4'-dimethoxy-4,6-dimethyl-spiro[1,3-dioxane-2,9'-thioxanthene]. [Figure 12] FIG. 12 shows the UV spectrum of 2'-methoxyspiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole]. [Figure 13] FIG. 13 shows the UV spectrum of 2′-methoxy-5,5-dimethyl-spiro[1,3-dioxane-2,6′-thiochromeno[2,3-e][1,3]benzodioxole]. [Figure 14] FIG. 14 shows the UV spectrum of the known photoinitiator ITX (isopropylthioxanthene). [Figure 15]FIG. 15 shows the UV spectrum of a protected version of the 1,3-dioxolane of the known photoinitiator ITX. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] [Detailed Description of the Invention] Compounds of the Invention In a first aspect, the present invention provides a compound of formula I,

[0067] [ka]

[0068] wherein n is 1, 2, 3, 4, or 5, and one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0069] The present invention also relates to a compound of formula:

[0070] [ka]

[0071] wherein R is methyl, ethyl, or propyl, and one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio; The present invention provides a compound of the formula:

[0072] In one embodiment, one of the aromatic rings is substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, and the other aromatic ring is unsubstituted. For example, a ring may be substituted with one substituent selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, or with two substituents selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, or with three substituents selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, or with four substituents selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0073] In other embodiments, each of the aromatic rings is substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and ester thereof, aryloxy and arylthio. For example, each of the rings can be substituted with one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and ester thereof, aryloxy and arylthio, or one of the rings can be substituted with two substituents independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and ester thereof, aryloxy and arylthio, and the other of the rings is substituted with one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and ester thereof, aryloxy and arylthio, or one of the rings can be substituted with hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and ester thereof, aryloxy and arylthio. One of the rings may be substituted with three substituents independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, and the other ring may be substituted with one substituent selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, or one of the rings may be substituted with four substituents independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio, and the other ring may be substituted with one substituent selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy, and arylthio.

[0074] In the compounds of the invention, the alkoxy can be a C1-4 alkoxy, such as methoxy or t-butoxy. In some examples, the alkoxy can be selected from the group consisting of dimethoxy, trimethoxy, ethoxy, diethoxy, triethoxy, propoxy, dipropoxy, tripropoxy, t-butoxy, di-t-butoxy, tri-t-butoxy. In some examples, the compounds of the invention have two or more methoxy substituents on the aromatic ring. In some examples, the compounds of the invention have a methoxy substituent on each aromatic ring. In some examples, the compounds of the invention have two methoxy substituents on one of the aromatic rings. In some examples, the compounds of the invention do not include 2-methoxy-9H-thioxanthen-9-one, 3,6-dimethoxy-9H-thioxanthen-9-one, or any of their 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, 1,3-dioxonane derivatives falling within the scope of formula (I).

[0075] In the compounds of the invention, hydroxyalkyl may be a hydroxy(C1-4)alkyl group, for example, 2-hydroxyisopropyl.

[0076] In the compound of the present invention, the alkyl carbonate is a C1-4 alkyl carbonate, for example, t-Butyl carbonate It could be.

[0077] In the compounds of the invention, the ester may be a C1-4 alkyl acid ester, such as an acetic acid ester (acetate) or an ester of trifluoromethanesulfonic acid. In some examples, the ester is an ester in which adjacent carbon atoms of the ring are each bonded to a respective oxygen atom, thereby forming a five-membered ring. RingThe orthoester may be an orthoester that forms a cyclic orthoester. The cyclic orthoester may be derived from trimethyl, triethyl or tripropyl orthoformate, such as triisopropyl orthoformate. For example, in the case of trimethyl orthoformate, the resulting cyclic orthoester is 2-methoxybenzo[1,3]dioxole. In another example, the resulting cyclic orthoester may be 2-isopropoxybenzo[1,3]dioxole.

[0078] In the compounds of the invention, the acetal can be a C1-4 alkoxyalkyl group, such as methoxymethyl or ethoxyethyl. In some examples, the acetal can be a cyclic acetal in which adjacent carbon atoms of the ring are each bonded to a respective oxygen atom, thereby forming a 5- or 6-membered cyclic acetal.

[0079] In the compounds of the present invention, benzyloxy may be a benzyloxy group, including substituted or unsubstituted benzyl groups, wherein the substituents may be selected from the group consisting of C1-6 alkyl, e.g., methyl or ethyl, hydroxy, alkoxy, alkyl carbonate, acetal and ester.

[0080] In the compounds of the present invention, the oxyacetic acid and its esters may be oxyacetic acid or its esters, for example, oxyacetic acid esters in which the esterifying group is selected from vinyl ether addition products such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl, isonorbornyl, 2-methyl-2-adamantyl, 3-tetrahydrofuranyl 3-oxocyclohexyl, γ-butyrolactone-3-yl, mevalonolactone, γ-butyrolactone-2-yl, 3-methyl-γ-butyrolactone-3-yl, 2-tetrahydropyranyl, 2-tetrahydrofuranyl, 2,3-propylcarbonate-1-yl, ethoxyethyl, methoxyethoxyethyl or acetoxyethoxyethyl.

[0081] In the compounds of the present invention, aryloxy can be C5 or C6 aryloxy, for example, phenoxy, which can be substituted. In the compounds of the present invention, arylthio can be C5 or C6 arylthio, for example, phenylthio, which can be substituted. The substituents can be selected from the group consisting of C1-6 alkyl, for example, methyl or ethyl, hydroxy, alkoxy, alkyl carbonate, acetal, and ester.

[0082] In some embodiments of the present invention, all of the substituents on the aromatic ring may be the same.

[0083] In some embodiments of the invention, the 1,3-dioxolane ring may be unsubstituted. In some embodiments of the invention, the 1,3-dioxolane ring may be substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl, or vinyl in any substitution pattern. In some examples, (chloro)alkyl includes C1-6 (chloro)alkyl, such as (chloro)methyl, (chloro)ethyl, (chloro)propyl, and also includes (chloro)cycloalkyl, which may introduce two substituents on the 1,3-dioxolane ring to form a cyclic group, such as a 5- or 6-membered carbocyclic ring fused to the 1,3-dioxolane ring. In some examples, the 1,3-dioxolane ring may be substituted with one or more C1-6 alkyl groups, such as two or more C1-6 alkyl groups. For example, the 1,3-dioxolane ring may be substituted with geminal or vicinal C1-6 alkyl groups in any substitution pattern, such as geminal or vicinal methyl groups. In some examples, the 1,3-dioxolane ring may be substituted with one, two, three, or four C1-6 alkyl groups, such as one, two, three, or four methyl groups. In all of the above examples, C1-6 alkyl is understood to include methyl, ethyl, propyl, butyl, pentyl, and hexyl, and all positional isomers thereof.

[0084] In some embodiments of the invention, the 1,3-dioxane ring may be unsubstituted. In some embodiments of the invention, the 1,3-dioxane ring may be substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl, or vinyl in any substitution pattern. In some examples, (chloro)alkyl includes C1-6 (chloro)alkyl, such as (chloro)methyl, (chloro)ethyl, (chloro)propyl, and also includes (chloro)cycloalkyl, which may introduce two substituents on the 1,3-dioxane ring to form a cyclic group, such as a 5- or 6-membered carbocyclic ring fused to the 1,3-dioxane ring. In some examples, the 1,3-dioxane ring may be substituted with one or more C1-6 alkyl groups, such as two or more C1-6 alkyl groups in any substitution pattern. For example, the 1,3-dioxane ring may be substituted with geminal or vicinal C1-6 alkyl groups, such as geminal or vicinal methyl groups. In some examples, the 1,3-dioxane ring may be substituted with one, two, three, or four C1-6 alkyl groups, such as one, two, three, or four methyl groups. In all of the above examples, C1-6 alkyl is understood to include methyl, ethyl, propyl, butyl, pentyl, and hexyl, and all positional isomers thereof.

[0085] In some embodiments of the invention, the 1,3-dioxepane ring may be unsubstituted. In some embodiments of the invention, the 1,3-dioxepane ring may be substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl, or vinyl in any substitution pattern. In some examples, (chloro)alkyl includes C1-6 (chloro)alkyl, such as (chloro)methyl, (chloro)ethyl, (chloro)propyl, and also includes (chloro)cycloalkyl, which may introduce two substituents on the 1,3-dioxepane ring to form a cyclic group, such as a 5- or 6-membered carbocyclic ring fused to the 1,3-dioxepane ring. In some examples, the 1,3-dioxepane ring may be substituted with one or more C1-6 alkyl groups, such as two or more C1-6 alkyl groups in any substitution pattern. For example, the 1,3-dioxepane ring may be substituted with geminal or vicinal C1-6 alkyl groups, such as geminal or vicinal methyl groups. In some examples, the 1,3-dioxepane ring may be substituted with one, two, three, or four C1-6 alkyl groups, such as one, two, three, or four methyl groups. In all of the above examples, C1-6 alkyl is understood to include methyl, ethyl, propyl, butyl, pentyl, and hexyl, and all positional isomers thereof.

[0086] In some embodiments of the invention, the 1,3-dioxocane ring may be unsubstituted. In some embodiments of the invention, the 1,3-dioxocane ring may be substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl, or vinyl in any substitution pattern. In some examples, (chloro)alkyl includes C1-6 (chloro)alkyl, such as (chloro)methyl, (chloro)ethyl, (chloro)propyl, and also includes (chloro)cycloalkyl, which may introduce two substituents on the 1,3-dioxocane ring to form a cyclic group, such as a 5- or 6-membered carbocyclic ring fused to the 1,3-dioxocane ring. In some examples, the 1,3-dioxocane ring may be substituted with one or more C1-6 alkyl groups, such as two or more C1-6 alkyl groups in any substitution pattern. For example, the 1,3-dioxocane ring may be substituted with geminal or vicinal C1-6 alkyl groups, such as geminal or vicinal methyl groups. In some examples, the 1,3-dioxocane ring may be substituted with one, two, three, or four C1-6 alkyl groups, such as one, two, three, or four methyl groups. In all of the above examples, C1-6 alkyl is understood to include methyl, ethyl, propyl, butyl, pentyl, and hexyl, and all positional isomers thereof.

[0087] In some embodiments of the invention, the 1,3-dioxonane ring may be unsubstituted. In some embodiments of the invention, the 1,3-dioxonane ring may be substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl, or vinyl in any substitution pattern. In some examples, (chloro)alkyl includes C1-6 (chloro)alkyl, such as (chloro)methyl, (chloro)ethyl, (chloro)propyl, and also includes (chloro)cycloalkyl, which may introduce two substituents on the 1,3-dioxonane ring to form a cyclic group, such as a 5- or 6-membered carbocyclic ring fused to the 1,3-dioxonane ring. In some examples, the 1,3-dioxonane ring may be substituted with one or more C1-6 alkyl groups, such as two or more C1-6 alkyl groups in any substitution pattern. For example, the 1,3-dioxonane ring may be substituted with geminal or vicinal C1-6 alkyl groups, such as geminal or vicinal methyl groups. In some examples, the 1,3-dioxonane ring may be substituted with one, two, three, or four C1-6 alkyl groups, such as one, two, three, or four methyl groups. In all of the above examples, C1-6 alkyl is understood to include methyl, ethyl, propyl, butyl, pentyl, and hexyl, and all positional isomers thereof.

[0088] The compounds of the present invention may have good solubility in aqueous media before and after deprotection. This may be characterized by referring to the octanol-water partition coefficient, which may be calculated in various ways. For example, preferred compounds of the present invention have a calculated logP (ClogP) or milogP of less than 4.5, preferably less than 4.0, as measured using Molinspiration chemoinformatics software. In other cases, compounds of the present invention may have improved solubility after deprotection.

[0089] The invention also relates to deprotected and deblocked forms of compounds of formula I or Ia, wherein the ketal, e.g., diethyl ketal, dipropyl ketal, 1,3-dioxolane ketone blocking group or 1,3-dioxane ketone blocking group or 1,3-dioxane ketone blocking group or 1,3-dioxane blocking group, is removed to give compounds of formula II,

[0090] [ka]

[0091] wherein one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, hydroxyalkyl, oxyacetic acid, aryloxy and arylthio, and said compounds can be obtained by reacting a compound of formula I or Ia in the presence of an acid or in the presence of an acid and heat.

[0092] The compound of formula II can be obtained by reacting the compound of formula I or Ia in the presence of acid and heat. The acid treatment and heat treatment can be performed simultaneously or subsequently. For example, the compound of formula II can be obtained by first reacting the compound of formula I or Ia in the presence of acid, followed by subsequent heat treatment.

[0093] Examples of compounds of formula (I), (Ia) and formula (II) of the present invention are set out in Table 1 below, and selected compounds and their respective milogP values ​​are shown in Table 2.

[0094] [Table 1-1]

[0095] [Table 1-2]

[0096] [Table 1-3]

[0097] [Table 1-4]

[0098] [Table 1-5]

[0099] [Table 1-6]

[0100] [Table 1-7]

[0101] [Table 1-8]

[0102] [Table 1-9]

[0103] [Table 2-1]

[0104] [Table 2-2]

[0105] [Table 2-3]

[0106] Compositions and photoinitiation methods In a second aspect, the present invention relates to a composition comprising: A compound of formula I or Ia as defined above; and Chemically transformable substrates; wherein the compounds of formula I or Ia are precursors of reactive derivatives of formula II:

[0107] [ka]

[0108] wherein one or both of the aromatic rings are substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy and arylthio, said compound of formula II being obtainable by reacting a compound of formula I or Ia in the presence of an acid; Additionally, the convertible substrate may be converted in the presence of a compound of formula II by direct or indirect photoinitiation.

[0109] In the compositions of the second aspect, the compounds of formula I or Ia may be precursors of reactive derivatives of compounds of formula II having any substitution pattern as described above.

[0110] The compound of formula II can be obtained by reacting the compound of formula I or Ia in the presence of acid and heat. The acid treatment and heat treatment can be performed simultaneously or subsequently. For example, the compound of formula II can be obtained by first reacting the compound of formula I or Ia in the presence of acid, followed by subsequent heat treatment.

[0111] The composition of the present invention can be used in a photoinitiation process. Thus, in a third aspect of the present invention, (a) forming a layer of the composition of the second aspect of the present invention on a substrate; (b) applying an acid or generating an acid in situ to the predetermined areas of said layer and reacting said acid with a compound of formula I or formula Ia to form a reactive derivative of formula II in the predetermined areas of said layer; (c) exposing the layer with the reactive derivative present in the predetermined areas to electromagnetic radiation of a wavelength or energy suitable to generate a reactive species from a compound of formula II; and (d) causing said reactive species to directly or indirectly convert said chemically convertible substrate; A photoinitiation method is provided that includes:

[0112] In some embodiments, reacting an acid with a compound of formula I or Ia to form a reactive derivative of formula II can include the application of heat, which can be done simultaneously with the application of the acid or the in situ generation of the acid, or can be done after this step.

[0113] In some embodiments, the method may further comprise carrying out a pre-conversion and / or post-conversion heat treatment. In other words, (c) above, in which the layer having reactive derivatives is exposed to electromagnetic radiation, may be followed by a heat treatment to allow reaction of the chemically convertible substrate with any acid present. Similarly, (d) above, in which the reactive species cause conversion of the chemically convertible substrate, may be followed by a heat treatment to initiate hardening of the remaining converted substrate.

[0114] The reactive species can be, for example, a free radical species or an energetically excited form of the compound of formula II.

[0115] In one embodiment, an acid may be applied to selected areas of the layer to react with the compound of formula I or Ia to form the reactive derivative of formula II in the selected areas of the layer. The acid may be applied, for example, by spraying or inkjet printing.

[0116] In other embodiments, an acid generator is incorporated into the composition that is applied to the substrate. Photoacid generators (PAGs) are preferred, but thermal acid generators (TAGs) may also be utilized. The acid generator is a species that can generate an acid in response to an external stimulus, thereby generating an acid in situ, which reacts with a compound of formula I or Ia to form a reactive derivative of formula II in selected areas of the layer where the acid is generated. Although currently less preferred, the acid generator may be applied to the layer subsequent to its formation, for example by spraying or inkjet printing.

[0117] In some examples, the application of the acid or in situ generation of the acid is followed by a heat treatment step to sufficiently react the acid with the compound of formula I or Ia to form the reactive derivative of formula II in all selected areas of the layer. The heat treatment step may be carried out regardless of whether the acid is applied externally or generated by a photoacid generator or a thermal acid generator. The temperature and duration of the heat treatment may vary depending, for example, on the concentration and strength of the externally applied acid, or the strength and duration of exposure to electromagnetic radiation in the case of a photoacid generator.

[0118] A reactive derivative of formula II is formed in selected areas of the layer in a first step of the process. In a second step, reactive species are generated from the compound of formula II upon exposure to electromagnetic radiation of an appropriate wavelength. If the first step is carried out photochemically using a PAG, the wavelength of electromagnetic radiation used in the second step is different from that used in the first step and is selected to avoid further acid generation from the PAG. This allows the application of electromagnetic radiation in the second step to be carried out at high energy as flood radiation, which does not have to be carried out imagewise.

[0119] As used herein, a direct photoinitiated reaction is a reaction in which a reactive species generated from a compound of formula II directly causes the conversion of a chemically transformable substrate, which can occur, for example, when the reactive species directly initiates the polymerization of a polymerizable monomer.

[0120] Indirect photoinitiation is a reaction in which the reactive species generated from the compound of formula II indirectly causes the transformation of the reactive substrate. This can occur, for example, when the reactive species interacts with a second photoinitiator or synergist by transferring its energy or electrons to another species, which then initiates or causes the transformation of the chemically transformable substrate. Another example of an indirect photoinitiation is that the reactive species can photosensitize a photoacid generator to generate an acid, which can cause the transformation of the polymerizable substrate via cationic polymerization, or can remove an acid-labile protecting group of a protected polymer, making the polymer soluble in a suitable developer. In such a method, the generation of an acid that can cause the transformation of the polymerizable substrate can be carried out by applying heat. In some examples, dissolution and washing of the solubilized polymer can be followed by heat treatment to cure the remaining composition.

[0121] The composition of the present invention is particularly suitable as a photoresist composition. A layer of said composition on a substrate, such as may be used in the method of the third aspect of the present invention, is called a photoresist. Another aspect of the present invention is a photoresist layer formed from the composition of the second aspect of the present invention on a substrate.

[0122] The chemically transformable substrate can be a polymerizable substrate, such as a cationically polymerizable substrate or a free radical accelerated polymerizable substrate, or a substrate that includes an acid labile protecting group on a protected polymer that can be removed by acid in a suitable medium to render the polymer soluble.

[0123] The cationically polymerizable compounds may be monomers, oligomers, and / or prepolymers. These monomers, oligomers, and / or prepolymers may have different degrees of functionality. Mixtures including combinations of mono-, di-, tri-, and higher functional monomers, oligomers, and / or prepolymers may be used.

[0124] In a preferred embodiment, said monomer, oligomer or prepolymer comprises at least one epoxy, at least one vinyl ether or at least one oxetane group as polymerizable group.

[0125] Examples of monomers, oligomers or prepolymers containing at least one epoxide group include epichlorohydrin-bisphenol S based epoxides, epoxidized styrenic and more epichlorohydrin-bisphenol F and A based epoxides and epoxidized novolaks, cycloaliphatic polyepoxides, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyols, polyglycidyl ethers of polyoxyalkylene glycols, polyglycidyl esters of aromatic polyols, polyglycidyl ethers of aromatic polyols, urethane polyepoxy compounds, and bis-(3,4-epoxycyclohexyl)-adipate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, poly[(2-oxiranyl)-1,2-cyclohexanediol]-2-ethyl-2-(hydroxymethyl)-1,3-propanediol ether, 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0] Polyepoxy polybutadiene alicyclic epoxy compounds such as heptane-3-carboxylate; ether derivatives including diol derivatives such as 3-(bis(glycidyloxymethyl)methoxy)-1,2-propanediol, limonene oxide, 2-biphenyl glycidyl ether, 1,4-butanediol diglycidyl ether and neopentyl glycol diglycidyl ether; n-butyl glycidyl ether, distilled butyl glycidyl ether, 2-ethylhexyl glycidyl ether, C8-C10 aliphatic glycidyl ether, C12-C14 aliphatic glycidyl ether, o-cresyl glycidyl ether, p-tertiary butyl Glycidyl ethers such as phenyl glycidyl ether, nonylphenyl glycidyl ether, phenyl glycidyl ether, cyclohexanedimethanol diglycidyl ether, polypropylene glycol diglycidyl ether, polyglycol diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, trimethylopropane triglycidyl ether, castor oil triglycidyl ether, propoxylated glycerin triglycidyl ether, sorbitol polyglycidyl ether, glycidyl ester of neodecanoic acid, and the like; as well as glycidyl amines such as epoxidized metaxylylene diamine.

[0126] Examples of monomers, oligomers or prepolymers containing at least one vinyl ether group include ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, butanediol divinyl ether, hydroxyl butyl vinyl ether, cyclohexanedimethanol monovinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-methoxyphenyl vinyl ether, a-methylphenyl vinyl ether, b-methylisobutyl vinyl ether and b-chloroisobutyl vinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, dodecyl vinyl ether, diethylene glycol monovinyl ether, cyclohexanedimethanol divinyl ether, Vinyl ether, 4-(vinyloxy)butyl benzoate, bis[4-(vinyloxy)butyl]adipate, bis[4-(vinyloxy)butyl]succinate, 4-(vinyloxymethyl)cyclohexylmethyl benzoate, bis[4-(vinyloxy)butyl]isophthalate, bis[4-(vinyloxymethyl)cyclohexylmethyl]glutaric acid, tris[4-(vinyloxy)butyl]trimellitate, 4-(vinyloxy)butyl steatite, bis[4-(vinyloxy)butyl]hexanediyl biscarbamate, bis[4-(vinyloxy)methyl]cyclohexyl]methyl]terephthalate, bis[4-(vinyloxy)methyl]cyclohexyl]methyl]isophthalate, bis[4-(vinyloxy)butyl](4-methyl-1,3-phenylene)-biscarbamate, bis[4-vinyloxy)butyl](methylenedi-4 , 1-phenylene) biscarbamate and 3-amino-1-propane vinyl ether.

[0127] Examples of monomers, oligomers or prepolymers containing at least one oxetane group include 3,3'-oxybis(methylene)bis(3-ethyloxetane), 3-ethyl-3-hydroxymethyl-1-oxetane, the oligomeric mixtures 1,4-bis[3-ethyl-3-oxetanylmethoxy)methyl]benzene, 3-ethyl-3-[(phenylmethoxy)methyl]-oxetane, 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane and bis[1-ethyl(3-oxetanyl)]methyl ether, 3-ethyl-[(tri-ethoxysilylpropoxy)methyl]oxetane and 3,3-dimethyl-2(p-methoxy-phenyl)-oxetane.

[0128] The free radical polymerizable compounds may be monomers, oligomers, and / or prepolymers. These monomers, oligomers, and / or prepolymers may have different degrees of functionality. Mixtures such as combinations of mono-, di-, tri-, and higher functional monomers, oligomers, and / or prepolymers may be used.

[0129] In another preferred embodiment, said monomer, oligomer or prepolymer comprises at least one acrylate or at least one methacrylate group as polymerizable group.

[0130] Suitable free radical promoted polymerizable mono- or polyfunctional monomers are: isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isoamylstyryl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethylhexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl ... -Hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, vinyl ether acrylate, 2-acryloyloxyethyl succinate, 2-acryloxyethyl phthalate, 2-acryloxyethyl-2-hydroxyethyl-phthalate, lactone modified flexible acrylate, and t-butylcyclohexyl acrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-Nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, bisphenol A EO (ethylene oxide) adduct diacrylate, bisphenol A PO (propylene oxide) adduct diacrylate, hydroxypivalate neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethylol tricyclodecane diacrylate and polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, EO modified trimethylolpropane triacrylate, tri(propylene glycol) triacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxy tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerol propoxy triacrylate, and caprolactam modified dipentaerythritol hexaacrylate, or N-vinyl amides such as N-vinyl caprolactam or N-vinyl formamide; or substituted acrylamides such as acrylamide or acryloylmorpholine.

[0131] Other suitable monofunctional acrylates include caprolactone acrylate, cyclic trimethylolpropane formal acrylate, ethoxylated nonylphenol acrylate, isodecyl acrylate, isooctyl acrylate, octyldecyl acrylate, alkoxylated phenol acrylate, tridecyl acrylate, and alkoxylated cyclohexanone dimethanol diacrylate.

[0132] Other suitable difunctional acrylates include alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, dioxane glycol diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, and neopentyl glycol diacrylate.

[0133] Other suitable trifunctional acrylates include propoxylated glycerin triacrylate and propoxylated trimethylolpropane triacrylate.

[0134] Other higher functionality acrylates include ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated pentaerythritol tetraacrylate, methoxylated glycol acrylates and acrylate esters.

[0135] Additionally, methacrylates corresponding to the above acrylates may be used in conjunction with these acrylates.

[0136] Examples of polymerizable oligomers include epoxy acrylates, aliphatic urethane acrylates, aromatic urethane acrylates, polyester acrylates, and linear acrylic oligomers.

[0137] The use of a polymerizable substrate may result in the formation of a negative photoresist in which exposed portions or regions of the photoresist become insoluble in a photoresist developer via a polymerization reaction of the chemically transformable substrate. In the case of the cationically polymerizable substrate, there may be a heating step, the so-called post-exposure bake (PEB), after the exposure to UV light, which may also complete the polymerization reaction. The unexposed and unpolymerized portions may be dissolved and removed by a suitable photoresist developer. After the step with the developer, a patterned coating remains on the surface that is insoluble in the developer. Depending on the application of the photoresist, further steps may be performed to harden the coating, such as a curing step, which may be performed by application of additional exposure to heat and / or UV light, for example as a permanent coating such as a solder mask or a dielectric layer.

[0138] In the case of application of heat, this can be accomplished, for example, by heating on a hot plate, or by baking in a static or conveyored hot air circulating oven, or by using a conveyored infrared oven. In the case of additional exposure to light, this can be done, for example, by using a conveyor to pass the substrate under a lamp that emits one or more wavelengths of UV light suitable for initiating further free radical polymerization.

[0139] For temporary resists such as etch or plate resists, an additional hardening step is usually not required as it would make subsequent removal of the resist more difficult.

[0140] In other embodiments, the chemically convertible substrate can be a protected polymer, for example a polymer with a polar group protected by an acid labile group. Examples of suitable polymers protected by acid labile groups are described, for example, in US Patent Application Publication No. 4,491,628 A, the contents of which are incorporated herein by reference, and include poly(tert-butyloxycarbonyloxy-α-alkylstyrene), poly(p-tert-butyloxycarbonyloxy-α-methylstyrene), poly(tert-butyloxycarbonyloxystyrene), poly(p-tert-butyloxycarbonyloxy-styrene) and poly(tert-butylvinylbenzoate), poly(tert-butylmethacrylate), or copolymers thereof. In such examples, the acid labile group is the tert-butyl ester of the pendant carboxylic acid group of the polymer, or the tert-butyl carbonate of the pendant phenol of the polymer. Other examples of suitable polymers protected by acid labile groups are described in US Pat. No. 7,858,287 B2, US Pat. No. 9,529,259 B2, and US Pat. No. 6,136,499A, the contents of which are incorporated herein by reference.

[0141] This embodiment may form a positive photoresist in which the exposed portions of the photoresist become soluble in a photoresist developer via deprotection of the polymer and may then be removed by the developer, while the unexposed portions of the photoresist remain insoluble in the photoresist developer. After the developer process, a patterned coating remains on the surface that is insoluble in the developer. Further steps may be performed to harden the coating, such as a curing step that may be performed by applying heat. An example of an application of positive photoresist is high resolution lithography.

[0142] In other embodiments, the chemically transformable substrate can be a protected dissolution enhancer, e.g., a dissolution inhibitor that contains an acid labile group that generates a material that is a dissolution enhancer after an acid catalyzed hydrolysis reaction. Examples of dissolution inhibitors that contain acid labile groups and their uses are described in Introduction to Microlithography (2nd Edition) ISBN 0-8412-2848-5 and Figure 85, pages 223-227.

[0143] The composition may further comprise a quencher, also called an acid diffusion control agent or its photodegradable version. Such compounds control the diffusion of the acid generated by exposure in the resist film, thereby suppressing undesired chemical reactions in unexposed areas. The acid diffusion control agent may be a nitrogen-containing organic compound whose basicity does not change upon exposure or thermal treatment, and which is typically present in an amount of 0.005 to 5% by weight of the composition. Examples of acid diffusion control agents include amines such as secondary lower aliphatic amines, tertiary lower aliphatic amines such as trimethylamine, diethylamine, di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine, quaternary ammonium compounds, trialkylammonium compounds, amides, ureas, TBOC blocked amines, and combinations thereof.

[0144] Examples of photodegradable acid diffusion control agents include arylsulfonium or iodonium salts containing anions such as acetate, hydroxide, or sulfamate, as well as those disclosed in US Pat. No. 8,614,047 B2.

[0145] The composition may contain additional ingredients known in the art, such as crosslinkers, colorants, inorganic mineral fillers, surface modifiers such as flow agents and defoamers, free radical scavengers, stabilizers, plasticizers, adhesion promoters, etc.

[0146] Details of photoinitiation methods in which the compounds and compositions of the present invention may be used are described in WO2011 / 086389 A1, the contents of which are incorporated herein by reference in their entirety.

[0147] Further, the compounds and compositions are described in US2015241783 A1, US2016327869 A1, US2013357103 A1, "Photosensitized Chemically Amplified ResistTM (PSCARTM) 2.0 for High Throughput and High Resolution EUV Lithography: Dual Photosensitization of Acid Generation and Quencher Decomposition by Flood Exposure", S.Tagawa et al., Proc.SPIE Vol.10146, Advances in Patterned Materials and Processes XXXIV, 101460G (2017), "Ultra-High Sensitivity Enhancement by Photosensitized Chemically Amplified Resist (PS-CAR) Process", S.Tagawa et al., J.Photopolymer Science and Technology, 26(6), 825 (2013), and "High Resistance Sensitization by Combined Pattern and Flood Lithography", S.Nagahara et al. al., Proc. SPIE, 9048, 90481S (2014), the photosensitized chemically amplified resist (PSCAR) method. The electromagnetic radiation for patterning in the first stage can be, for example, EUV (13.5 nm), ArF (193 nm), KrF (248 nm), or an electron beam. The electromagnetic radiation used in the second stage as flood radiation is a 365 nm, 375 nm, 385 nm, 395 nm, 405 nm, or 415 nm LED, or a UV lamp with a broader wavelength distribution. Synthesis of Compounds of the Invention The compounds of the present invention of formula I may be synthesized by a variety of methods.

[0148] For example, compounds of formula I in which one or both rings of the spiro[(1,3)dioxolane-2,9'-thioxanthene] structure are substituted with hydroxy or hydroxyalkyl groups can be prepared by first preparing the corresponding hydroxy or hydroxyalkyl substituted 9H-thioxanthen-9-one compound, followed by protecting the hydroxy group with a suitable protecting group, which can then be removed. The protected structure is then reacted with ethylene glycol to protect the carbonyl group with a 1,3-dioxolane group, or with 1,3-propylene glycol to protect the carbonyl group with a 1,3-dioxane group, or with 1,4-butanediol to protect the carbonyl group with a 1,3-dioxepane group, or with 1,5-pentanediol to protect the carbonyl group with a 1,3-dioxocane group, or with 1,6-hexanediol to protect the carbonyl group with a 1,3-dioxonane group. Other glycols can be used to generate substituted dioxolane or dioxane groups. The hydroxy protecting group can then be removed to generate, for example, hydroxy or hydroxyalkyl substituted spiro[(1,3)dioxolane-2,9'-thioxanthene] compounds.

[0149] For example, compounds of formula I in which one or both rings of the spiro[(1,3)dioxolane-2,9'-thioxanthene] structure are substituted with alkoxy groups can be synthesized by first preparing the corresponding alkoxy-substituted 9H-thioxanthen-9-one compound.

[0150] An alkoxy substituted 9H-thioxanthen-9-one compound is reacted with Lawesson's reagent (2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetan-2,4-dithione) followed by reaction with ethylene glycol. This synthetic route is shown in the specific reaction scheme below:

[0151] [ka]

[0152] Scheme 1 The alkoxy, hydroxy and hydroxyalkyl substituted 9H-thioxanthen-9-one precursors can be prepared by a variety of synthetic routes.

[0153] In the case of hydroxyalkyl-substituted 9H-thioxanthen-9-one precursors, these can be prepared from the corresponding alkyl-substituted compounds via bromination with a suitable brominating agent, such as N-bromyl succinimide (NBS), followed by treatment with an alkali, such as sodium hydroxide. This synthetic route is shown in the specific reaction scheme below:

[0154] [ka]

[0155] Scheme 2 In the case of alkoxy and hydroxy substituted 9H-thioxanthen-9-one precursors, these can be produced by the following synthetic routes:

[0156] [ka]

[0157] Scheme 3

[0158] [ka]

[0159] Scheme 4

[0160] [ka]

[0161] Scheme 5

[0162] [ka]

[0163] Scheme 6

[0164] [ka]

[0165] Scheme 7 It is within the skill of the art to modify any of the above synthetic methods to synthesize any of the compounds within the scope of the invention that are not explicitly exemplified. EXAMPLES

[0166] The invention is illustrated by the following non-limiting examples.

[0167] Example 1 Synthesis of 3,4-dimethoxy-9H-thioxanthen-9-one Stage I: 2,3-Dimethoxy-1-iodobenzene 1,2-Dimethoxybenzene (200g, 1.447mol) was dissolved in dry tetrahydrofuran (2000ml) and cooled to -10°C under nitrogen. A 1.6M solution of n-butyllithium in hexane (1005ml, 1.608mol) was added via the dropping funnel and the reaction mixture was then allowed to warm to room temperature over approximately 2 hours. A yellow precipitate formed as the mixture warmed. The mixture was then cooled to -45°C and a solution of iodine (402g, 1.584mol) in dry tetrahydrofuran (2800ml) was added dropwise rapidly and the reaction mixture was then allowed to warm to room temperature overnight. The reaction mixture was quenched into water containing 10% sodium metabisulfite (20lt). The upper layer was removed and the aqueous layer extracted with diethyl ether (3×2lt). The combined organics were washed with sodium bicarbonate solution (5lt) and water (5lt) then dried over sodium sulfate. The solution was filtered through GF / F and the solvent removed under reduced pressure leaving an orange-brown oil, 347g. This was adsorbed onto silica gel (600g) and then loaded onto a wet (hexane) loaded silica gel (3000g) column. After passing through hexane (10lt) the polarity was increased to 5% ethyl acetate in hexane (30lt) to remove the product. The good fractions were concentrated to an orange oil, 106g, 0.401mol, 27.7%, with a GC purity of 77%. This was used in the next step without further purification.

[0168] Stage II: 2-[(2,3-dimethoxyphenyl)thio]benzoic acid 2,3-Dimethoxyiodobenzene (106 g, 0.401 mol) and thiosalicylic acid (52 g, 0.337 mol) were dissolved in amyl alcohol (1100 ml). To this mixture was added potassium carbonate (139 g, 0.237 mol) and anhydrous copper(II) acetate (17 g, 0.0935 mol). The mixture was heated at reflux overnight (16 h) and then checked for completion by TLC (eluent 2:1 hexane / ethyl acetate).

[0169] The reaction was cooled to room temperature and then poured into approximately 2000 ml of water, which was confirmed to be basic. The mixture was filtered through a GF / F fiber pad to remove suspended copper salts. The upper organic layer was separated and discarded. The aqueous layer was extracted with diethyl ether (2 x 1000 ml), which was also discarded. The lower aqueous layer was acidified to pH 1 with hydrochloric acid, forming a brown precipitate. This was extracted with ethyl acetate (3 x 500 ml) and dried over sodium sulfate. The solution was filtered and concentrated to a brown solid, which was triturated with t-butyl methyl ether and collected by vacuum filtration. The solid was dried to give a light brown powder, yield 36 g, HPLC 87.07%.

[0170] The above organic extracts were concentrated to dryness under high vacuum and the residue was partitioned between water (1000 ml) and ethyl acetate (2 x 500 ml). The organic layer was dried over sodium sulfate, filtered and concentrated to a brown solid. This was triturated with t-butyl methyl ether, collected by vacuum filtration and the light brown solid was dried to give 49 g with a purity of 99.04% by HPLC.

[0171] Stage III: 3,4-dimethoxy-9H-thioxanthen-9-one 2-[(2,3-Dimethoxyphenyl)thio]benzoic acid (36 g, 0.11 mol) from the first crop was added portionwise to 95% sulfuric acid (360 ml) stirred at room temperature. A slight increase in temperature was observed (19-28°C). After 1 hour, the reaction mixture was checked by TLC (2:1 hexane / ethyl acetate) to confirm completion of the reaction. The reaction mixture was carefully poured into a mixture of water and ice (approximately 2500 ml) and the resulting solid was collected by vacuum filtration (very slow) and washed thoroughly with water. The solid was dissolved in ethyl acetate (3 lt), washed with a solution of sodium bicarbonate and then dried over sodium sulfate. It was filtered through a pad of GF / F fibre and the resulting solution was concentrated to dryness leaving an off-white solid.

[0172] Yield: 23.5 g, 0.086 mol, yield 69.4%, purity by HPLC 95.24%.

[0173] 2-[(2,3-dimethoxyphenyl)thio]benzoic acid (49g, 0.169mol) from the second crop was added portionwise to 95% sulfuric acid (490ml) stirred at room temperature. A slight increase in temperature was observed (19.7-29.2°C). After 1 hour, the reaction mixture was checked by TLC (2:1 hexane / ethyl acetate) and reaction completion was observed. The reaction mixture was carefully poured into a mixture of water and ice (~3500ml) and the resulting solid was extracted into ethyl acetate (5lt), washed with sodium bicarbonate solution and then dried over sodium sulfate. It was filtered through a GF / F fibre pad and the resulting solution was concentrated to dryness leaving an off-white solid.

[0174] Yield: 36 g, 0.132 mol, yield 78.1%, purity by HPLC 96.45%.

[0175] The UV absorption spectrum of this compound is shown in FIG.

[0176] Example 2 Synthesis of 3,4-dihydroxy-9H-thioxanthen-9-one A solution of 3,4-dimethoxy-9H-thioxanthen-9-one (47g, 0.173mol) in dichloromethane (1600ml) was added to a solution of boron tribromide (38ml, 98.8g, 0.394mol, 2.1eq) in dichloromethane (940ml) under nitrogen atmosphere at -20°C. A deep purple colour formed quickly which gradually turned to a deep red. The reaction was stirred overnight and allowed to warm to room temperature. TLC (1:1 hexane / ethyl acetate) showed the reaction was complete. The reaction was poured into water / ice (5000ml) and stirred for 15 minutes whereupon a solid formed. The product was extracted with ethyl acetate (3x3lt) and the combined organics washed with sodium chloride solution, dried over sodium sulphate and then filtered through a GF / F fibre pad. The solvent was removed in vacuo to leave a thick suspension which was allowed to stand overnight. The solid was collected by filtration, washed on the filter with ethyl acetate and t-butyl methyl ether, and dried to constant weight.

[0177] The yield was 35 g, the yield rate was 82.7%, and the HPLC purity was 98.78%.

[0178] The filtrate was concentrated to give a second crop, which was obtained in 1.7 g with a purity of 93.03%.

[0179] The UV absorption spectrum of this compound is shown in FIG.

[0180] Example 3 Synthesis of 1,5,6-trimethoxy-9H-thioxanthen-9-one Stage I: 2,3-Dimethoxybenzenethiol 1,2-Dimethoxybenzene (710 g, 5.139 mol) and N,N,N,N-tetramethylethylenediamine (8 ml, 53.5 mmol) were dissolved in dry tetrahydrofuran (7100 ml) under a nitrogen atmosphere. The mixture was cooled to -45°C and a 1.6 M solution of n-butyllithium in hexane (3550 ml, 5.68 mol) was added via a dropping funnel. The reaction was stirred and allowed to warm to room temperature for 2 hours (72.3% of the unlithiated material remained) and a yellow precipitate gradually formed. After 21 hours the mixture showed 45.4% lithiated product and the reaction was cooled to -70°C and elemental sulfur (95 g, 2.96 mol) was added in portions below -60°C, an immediate exotherm was observed and a brown solution formed. The reaction was stirred and allowed to warm to room temperature overnight.

[0181] The reaction mixture was poured into approximately 20 lt water and the upper organic layer discarded. The aqueous solution was extracted with diethyl ether (3 x 3000 ml) which was discarded. The aqueous layer was acidified to pH 1 with hydrochloric acid and extracted with diethyl ether (3 x 3000 ml). The combined organic extracts were washed with water (2000 ml) then dried over sodium sulphate. This was filtered through GF / F and the solvent removed to leave a brown oil. 531 g, 84.3% yield = 448 g, 51.2% yield (material still contained 11.2% 1,2-dimethoxybenzene).

[0182] Stage II: 2-[(2,3-dimethoxyphenyl)thio]-6-methoxybenzoic acid 2,3-Dimethoxybenzenethiol (105g@84.3%, 0.52mol) and 2-bromo-6-methoxybenzoic acid (89g, 0.385mol) were dissolved in amyl alcohol (1500ml) and stirred under nitrogen. To this was added anhydrous potassium carbonate (172.5g, 1.248mol) and anhydrous copper(II) acetate (21g, 0.1156mol). The reaction was heated to reflux overnight (19hrs) and then checked for completion by TLC (eluent 2:1 hexane / ethyl acetate). The reaction was cooled to room temperature, the amyl alcohol removed under high vacuum and the residue dissolved in water (5lt). The aqueous solution was extracted with diethyl ether (3×1lt) and discarded. The aqueous layer was then acidified to pH 1 with hydrochloric acid. The product was extracted with dichloromethane (3×500ml) and the combined organics dried over sodium sulfate and filtered through GF / F. The solvent was removed in vacuo leaving a thick brown oil which crystallized overnight. The solid was triturated with t-butyl methyl ether, collected by filtration and dried leaving 32 g @ 98.36% HPLC purity.

[0183] The filtrate was concentrated to a brown oil, 52 g / HPLC purity 80.56%, which was used in the next step without further purification.

[0184] Stage III: 1,5,6-trimethoxy-9H-thioxanthen-9-one Sulfuric acid (500ml) was carefully added to the crude 2-[(2,3-dimethoxphenyl)thio]-6-methoxybenzoic acid (52g) and the mixture was stirred at room temperature for approximately 2 hours. TLC (eluent 1:1 ethyl acetate / hexane) showed the reaction was complete. The reaction mixture was poured into ice / water (5lt) and the product was extracted with dichloromethane (3x1lt) and the combined organic extracts were washed with saturated sodium bicarbonate solution (1lt). The organic layer was dried over sodium sulfate, filtered through GF / F and concentrated to dryness. The residue was triturated with ethanol and a light brown solid was collected by filtration. The product was dried to give 12.2g which was combined with the product of the next reaction.

[0185] 2-[(2,3-dimethoxyphenyl)thio]-6-methoxybenzoic acid (32g, 0.0999mol) was added portionwise to stirred sulphuric acid (320ml) at room temperature. The mixture was stirred for 1 hour then quenched into ice / water (approximately 3.2lt) and left overnight. Work-up was as above and the resulting solid was combined with the solid from the above reaction.

[0186] Total yield 18 g, HPLC purity 96.65%.

[0187] The UV absorption spectrum of this compound is shown in FIG.

[0188] Example 4 Synthesis of 1,5,6-trihydroxy-9H-thioxanthen-9-one The 1,5,6-trihydroxy compound was produced by demethylating the 1,5,6-trimethoxy compound from Example 3 using boron tribromide.

[0189] Boron tribromide (12.85 g, 5 ml, 0.0513 mol) was dissolved in dichloromethane (100 ml) and cooled to -20°C under a nitrogen atmosphere.

[0190] A solution of 1,5,6-trimethoxy-9H-thioxanthen-9-one (5 g, 0.0165 mol) in dichloromethane (170 ml) was added dropwise. The reaction was stirred and allowed to warm to room temperature overnight (note the immediate dark orange color observed). TLC (eluent toluene / ethyl acetate / formic acid, 5:4:1) indicated the reaction was complete. The reaction mixture was poured into a mixture of ice and water. A red precipitate formed which was filtered through GF / F paper. The aqueous layer was extracted with ethyl acetate (2×100 ml), dried over sodium sulfate, filtered, and concentrated to a red solid (<1 g). The red solid was re-extracted several times with ethyl acetate and the solution was filtered through a pad of silica gel to remove baseline material. The solution was concentrated to an orange / red solid in a total yield of 1.9 g, HPLC 79.81% (still showing some starting material). 1 HNMR indicates the desired material was present.

[0191] Example 5 Synthesis of 2,3-dimethoxy-9H-thioxanthen-9-one Stage I: Methyl 3,4-dimethoxybenzoate 3,4-Dimethoxybenzoic acid (1000g, 5.49mol) was suspended in methanol (5lt) and stirred. To this was added 95% sulphuric acid (200ml) and the mixture was then heated to reflux for approximately 15 hours before being cooled to room temperature overnight. The reaction mixture was carefully poured into saturated sodium bicarbonate solution with stirring resulting in the formation of a white foamy precipitate. The product was extracted with t-butyl methyl ether (3 x 4lt) and then dried over sodium sulphate. The sodium sulphate was removed by filtration through GF / F and the solvent removed under reduced pressure to give a white solid, 1070g, GC 99.7%.

[0192] Stage II: Methyl 2-bromo-4,5-dimethoxybenzoate Methyl 3,4-dimethoxybenzoate (1070g, 5.45mol) was dissolved in glacial acetic acid (5lt) and cooled to 10°C (at lower temperatures the solution becomes a solid). A solution of bromine (880g, 5.51mol) in acetic acid (2.5lt) was added over approximately 4 hours, keeping the temperature at approximately 10°C. After stirring overnight the reaction was approximately 50% brominated, this did not change after a further 3 days of stirring and the addition of a catalytic amount of iron powder. The reaction was carefully poured into water (25lt) containing approximately 10% sodium metabisulphite forming a white solid. The solid was collected by filtration, washed thoroughly on the filter with demineralised water (5lt) and the solid was dried overnight in a fan oven at 50°C.

[0193] Yield: 1013g with GC purity 82.1%.

[0194] The product was purified by dissolving in refluxing methanol (2 lt) then slowly cooling to room temperature and standing for 3 days. The crystalline solid was collected by filtration, washed on the filter with a small amount of methanol and dried to constant weight. This gave a yield of 468 g (~31%) with a GC purity of 99.0%.

[0195] A second crop (52 g) was obtained with lower purity (86%) which was discarded.

[0196] Stage III: 2-bromo-4,5-dimethoxybenzoic acid.

[0197] Methyl 2-bromo-4,5-dimethoxybenzoate (367g, 1.334mol) was added to a solution of potassium hydroxide (112g, 2.00mol) in demineralised water (2lt). The suspension was heated to reflux for 2 hours by which time a clear solution was obtained. TLC (eluent 1:1 ethyl acetate / hexane) showed the reaction was complete. The solution was cooled to room temperature, diluted with demineralised water (5lt) and then acidified to pH 1 with concentrated hydrochloric acid. The resulting white solid was collected by filtration, washed thoroughly on the filter with demineralised water (~5lt) and the solid was dried for several hours before being dried to constant weight in a fan oven at 50°C.

[0198] The yield was 339 g, 1.30 mol, 97.45%, and the purity by HPLC was 99.64%.

[0199] Stage IV: 4,5-Dimethoxy-2-(phenylthio)benzoic acid 2-Bromo-4,5-dimethoxybenzoic acid (121 g, 0.463 mol) was dissolved in amyl alcohol (1500 ml) under nitrogen atmosphere. To this was added thiophenol (56 g, 0.508 mol), potassium carbonate (207 g, 1.5 mol) and anhydrous copper(II) acetate. The mixture was stirred and heated at reflux overnight. The reaction was then cooled to about 35°C, the solvent removed under high vacuum and the resulting residue partitioned between water (3 lt) and ethyl acetate (3 lt). The two layers were separated and the aqueous layer extracted with ethyl acetate (2 x 500 ml) and discarded. The aqueous layer was acidified to pH 1 with hydrochloric acid (32%). The product was extracted with ethyl acetate (3 x 1000 ml) and the combined extracts dried over sodium sulfate then filtered through GF / F. Removal of the solvent left an off-white solid (106 g) which was triturated with t-butyl methyl ether and then allowed to stand overnight. The solid was collected by filtration, washed with t-butyl methyl ether and dried to constant weight. This gave an off-white solid, 85 g, HPLC purity 84.22%. (7 g of second crop material @ 95.66% was obtained).

[0200] This was attempted in the next step and was found to give good material without the need for purification.

[0201] Some material was obtained from the ester (methyl 2-bromo-4,5-dimethoxybenzoate), but required additional work-up to be sufficiently pure before it could be cyclized.

[0202] Stage V: 2,3-Dimethoxy-9H-thioxanthen-9-one 4,5-Dimethoxy-2-(phenylthio)benzoic acid (112g @ 84.22%, 0.349mol) was added portionwise to stirred 95% sulfuric acid (1200ml) and a temperature increase from 18.9-28.6°C was observed. The mixture was stirred at room temperature overnight. The reaction was shown to be complete by TLC (eluent ethyl acetate / hexane 1:1). The reaction mixture was poured into ice / water (8lt) and the solid extracted with ethyl acetate (3 x 5lt). The ethyl acetate solution was washed with saturated sodium bicarbonate solution (5lt) and dried over anhydrous sodium sulfate. The salts were removed by filtration through a GF / F pad and the solvent removed under reduced pressure to leave a pale yellow solid. This was triturated with a small amount (~150ml) of ethanol and the solid collected by vacuum filtration.

[0203] This gave the product (81 g, 85.1%) as a pale yellow powder with a purity of 99.32% by HPLC and 100% by GLC.

[0204] The UV absorption spectrum of this compound is shown in FIG.

[0205] Example 6 Synthesis of 2,3-dihydroxy-9H-thioxanthen-9-one.

[0206] Boron tribromide (9.7 g, 0.0387 mol) was dissolved in dichloromethane (100 ml) under nitrogen atmosphere. The solution was cooled to -20°C and then a solution of 2,3-dimethoxy-9H-thioxanthen-9-one (5 g, 0.0184 mol) (from Example 3) in dichloromethane (100 ml) was added dropwise at -20°C. A deep yellow solution formed which gradually darkened to orange. The reaction was allowed to warm slowly to room temperature and stirred for 4 days. TLC showed the reaction to be complete (hexane / ethyl acetate 2:1) and quenched by dropwise addition of water (250 ml) and then stirred for 1 hour to ensure hydrolysis of the boron complex. Ethyl acetate (500 ml) was added which resulted in the formation of an emulsion. This was filtered through GF / F to attempt separation. The organic layer was separated and washed with saturated sodium bicarbonate solution, then dried over sodium sulfate and filtered through GF / F. The clear solution was concentrated leaving a yellow solid (first crop). The solid filtered off above was dissolved in tetrahydrofuran and found to also be the product (by TLC). This solution was filtered through GF / F, dried, combined with the first crop material and triturated with t-butyl methyl ether. This was collected by filtration and dried to give the product as a yellow powder, 3.9 g, 86.8%. The purity by HPLC was 92.59% and the structure was confirmed. 1 Confirmed by 1 H NMR.

[0207] The UV absorption spectrum of this compound is shown in FIG.

[0208] Example 7 Synthesis of 2',3'-dimethoxyspiro[(1.3)-dioxolane-2,9'-thioxanthene] Stage I: 2,3-Dimethoxy-9H-thioxanthene-9-thione Test 1 2,3-Dimethoxy-9H-thioxanthen-9-one (5 g, 0.0184 mol) was added to toluene (150 ml) under nitrogen atmosphere. To this was added Lawesson's reagent (2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiaphosphetane-2,4-dithione) (5.5 g, 0.0136 mol). The mixture was stirred and heated at 80° C. for 2 hours after which TLC (eluent 2:1 hexane / ethyl acetate) revealed the reaction to be complete. The reaction was cooled to room temperature and diluted with hexane / dichloromethane, 4:1 (250 ml). It was then filtered through a pad of silica gel and washed with hexane / dichloromethane (2×250 ml). The filtrate was stripped to a brown solid, 7.8 g, GC 77.8%. Silica passes through dark impurities. The brown solid was dissolved in ethyl acetate / hexane (2:1) and filtered through a pad of silica gel. This removed the baseline material but was very dark in color. The solvent was removed leaving a black solid. This was again dissolved in ethyl acetate / hexane (2:1) and this time passed through a pad of neutral alumina, flushing the column with ethyl acetate / hexane (2:1). The filtrate was light yellow and was concentrated to a red solid, 4.9 g, GC 95.7%.

[0209] Test 2 2,3-Dimethoxy-9H-thioxanthen-9-one (5 g, 0.0184 mol) was dissolved in toluene (625 ml) under nitrogen atmosphere. To this was added phosphorus pentasulfide (32.8 g, 0.0738 mol). The mixture was then heated to reflux overnight and TLC (eluent hexane / ethyl acetate 2:1) indicated the reaction was complete. The reaction was cooled to room temperature and filtered through a GF / F fiber pad. The filter cake was washed with dichloromethane and the combined organic filtrate was concentrated to a dark solid which was dissolved in dichloromethane / hexane (1:1) and filtered through a pad of acidic alumina. The filtrate was stripped to a dark solid, 4 g, which was used directly in the next step.

[0210] Stage II: 2',3'-dimethoxyspiro[(1.3)-dioxolane-2,9'-thioxanthene].

[0211] 2,3-Dimethoxy-9-H-thioxanthene-9-thione (4 g, 0.0139 mol) was suspended in acetonitrile (85 ml) under nitrogen atmosphere. To this was added ethylene glycol (1.2 g, 0.0193 mol), triethylamine (7.5 ml) and finally silver trifluoroacetate (11.6 g, 0.0525 mol). The mixture was stirred at room temperature (a slight exotherm of 8 degrees was observed) followed by TLC (eluent hexane / ethyl acetate 2:1). After stirring overnight the reaction was complete. GC showed no starting material and 84.4% product. Acetonitrile and trimethylamine were removed in vacuo and the residue was partitioned between ethyl acetate (100 ml) and brine (100 ml). This was filtered through GF / F and the filter cake was washed with ethyl acetate (100 ml). The two layers were separated and the aqueous layer was further extracted with ethyl acetate (2 x 100 ml). The combined organics were dried over sodium sulfate and then filtered through a pad of GF / F fiber. The filtrate was concentrated to 6 g of an orange oil which was triturated with t-butyl methyl ether and the solid was collected and dried to give 5.6 g.

[0212] This material was subjected to purification.

[0213] The crude product was dissolved in isopropyl alcohol (50ml) under nitrogen and warmed to 50-55°C. To this was added sodium borohydride (0.5g, 0.0132mol), which caused an immediate colour change (orange to yellow) and after 6 hours the ketone remained so another 1g of sodium borohydride was added and heating continued for a further 8 hours. The reaction was allowed to stir and cool overnight. GC showed mainly a single peak and the reaction was poured into water, extracted with ethyl acetate (2x100ml), dried over sodium sulphate, filtered through GF / F and concentrated to a viscous oil. This was dissolved in toluene (200ml) and passed through a small pad of basic alumina, washing with further toluene. The filtrate was concentrated to a viscous solid, GC 96%, which slowly crystallised overnight. The solid was triturated with a few ml of ethanol and cooled in the fridge for 1-2 hours. The solid was collected by filtration and washed with t-butyl methyl ether. This was dried to give 2.5g of a white solid. This material and 0.52 g from above were dissolved in dichloromethane then concentrated to dryness, the residue triturated with t-butyl methyl ether (approximately 20 ml) and the white solid collected by filtration and washed on the filter with several milliliters of t-butyl methyl ether.

[0214] The purity by HPLC is 99.9% and the structure is 1 Confirmed by 1 H NMR.

[0215] The UV absorption spectrum of this compound is shown in FIG.

[0216] Example 8 Synthesis of 2,3,5-trimethoxy-9H-thioxanthen-9-one Stage I: 4,5-Dimethoxy-2-[(2-methoxyphenyl)thio]benzoic acid 2-Bromo-4,5-dimethoxybenzoic acid (85 g, 0.326 mol) and 2-methoxybenzenethiol (50 g, 0.359 mol) were dissolved in amyl alcohol (1275 ml) under a nitrogen atmosphere. To this solution was added anhydrous potassium carbonate (146.3 g, 1.06 mol), and anhydrous copper(II) acetate (10 g). The mixture was then heated to reflux for 48 hours, by which time TLC (ethyl acetate x 2) indicated that the reaction was essentially complete. The solvent was removed under high vacuum and the residue dissolved in water (2 lt). The aqueous phase was extracted with ethyl acetate (2 x 1 lt) and set aside. The aqueous phase was acidified to pH 1 with 32% hydrochloric acid and the resulting solid was collected by filtration and then washed successively on the filter with water, ethanol ethyl acetate and t-butyl methyl ether. The pale yellow solid was dried to constant weight to give 67 g, 0.209 mol, 64.1%, HPLC purity 93.15%. The structure was confirmed by proton NMR.

[0217] Stage Ia: 4,5-dimethoxy-2-[(2-methoxyphenyl)thio]benzoyl chloride 4,5-Dimethoxy-2-[(2-methoxyphenyl)thio]benzoic acid (10 g, 0.313 mol) was suspended in dichloromethane (50 ml) and stirred under nitrogen. To this was added oxalyl chloride (8 ml, 0.0932 mol) and 5 drops of N,N-dimethylformamide. The reaction was stirred at room temperature for 1 hour, at which point the solid changed colour from yellow to orange. The mixture was then heated to reflux for 4 hours, at which point the solid dissolved and a clear orange-red solution was obtained. The solvent and volatiles were removed under vacuum and more dichloromethane was added and evaporated to leave a dark orange / brown oil which slowly solidified. The yield was 11 g, which was stored under nitrogen and used in the next step without further purification.

[0218] Stage II: 2,3,5-trimethoxy-9H-thioxanthen-9-one 4,5-Dimethoxy-2-[(2-methoxyphenyl)thio]benzoyl chloride (11 g, 0.0325 mol) was dissolved in dichloromethane (135 ml) and cooled to 0-5°C under nitrogen. Aluminium chloride (6.3 g, 0.0472 mol) was added portionwise, causing the solution to turn red and a solid to precipitate. The mixture was stirred at room temperature for 30 minutes and then cooled back to 0°C. The reaction was quenched by the addition of 2M hydrochloric acid (150 ml) and allowed to warm and stir at room temperature for 30 minutes. The solid present was collected by filtration and the aqueous solution extracted with dichloromethane (2 x 300 ml). The combined organics were washed with 10% potassium hydroxide solution (2 x 100 ml) and then dried over sodium sulfate. The inorganics were filtered off through GF / F and the solvent removed leaving 6 g of a yellow solid. After further extraction of only the aqueous layer, 0.5 g of product was collected. The two solids were triturated with methanol (50 ml) then collected by filtration and dried.

[0219] Yield: 5.7 g, purity by HPLC: 84.31%.

[0220] The previously filtered solid was dried to give 2.24 g, HPLC 95.62%, containing inorganics.

[0221] Both samples were recrystallized from toluene (85–95 vol.) and hot filtered through a GF / F fiber pad to remove insoluble material.

[0222] From 5.7g, 3.5g @ 91.39% was obtained.

[0223] The UV absorption spectrum of this compound is shown in FIG.

[0224] The carbonyl compound of this example can be reacted with ethylene glycol according to Scheme 1 above to give the compound 2,3,5-trimethoxyspiro[(1,3)dioxolane-2,9'-thioxanthene].

[0225] Example 9 Synthesis of 2,3,7-trimethoxy-9H-thioxanthen-9-one Stage I: 4,5-Dimethoxy-2-[(4-methoxyphenyl)thio]benzoic acid 2-Bromo-4,5-dimethoxybenzoic acid (85g, 0.326mol) and 4-methoxybenzenethiol (50g, 0.359mol) were dissolved in amyl alcohol (1275ml) under nitrogen atmosphere. To this solution was added anhydrous potassium carbonate (146.3g, 1.06mol), and anhydrous copper(II) acetate (15g). The mixture was then heated to reflux for 24 hours, at which time TLC (toluene / ethyl acetate / formic acid 5:4:1) showed the reaction was essentially complete. The solvent was removed under high vacuum and the residue was dissolved in water (2lt). This was then filtered to remove any retained suspended material. The aqueous phase was extracted with t-butyl methyl ether (3x500ml) which was set aside. The aqueous phase was acidified to pH 1 with 32% hydrochloric acid, the product extracted with ethyl acetate (3x1lt) and the combined organic extracts were dried over sodium sulfate, filtered and concentrated to a brown oily solid. This was triturated with t-butyl methyl ether and collected by filtration, and dried to give 31 g of a pale pink solid with an HPLC purity of 33.66%.

[0226] The yellow solid from the first filtration (72g) was treated with hydrochloric acid and the product extracted with a mixture of tetrahydrofuran and ethyl acetate (1:1) (4lt). This was dried over sodium sulfate, filtered and concentrated to a yellow solid which gradually turned grey / green in colour. This was triturated with ethanol, collected by filtration and washed on the filter with ethanol and t-butyl methyl ether. This was dried to a grey solid 47g@85.41%.

[0227] The filtrate was concentrated to give a small second crop of a white solid, 4 g, 98.17%, which was subjected to proton NMR, which confirmed the product to be the desired one.

[0228] Stage II: 2,3,7-trimethoxy-9H-thioxanthene Test 1 4,5-Dimethoxy-2-[(4-methoxyphenyl)thio]benzoic acid, second crop (1 g, 0.0031 mol) was added with stirring to 95% sulfuric acid (10 ml) and the mixture was stirred at room temperature overnight. TLC showed the reaction was complete so the reaction mixture was poured onto ice (100 g). The product was extracted with ethyl acetate (3×100 ml) and the combined organic extracts were washed with saturated sodium bicarbonate solution (100 ml) then dried over sodium sulfate and filtered. The solvent was removed under reduced pressure leaving a yellow solid, 0.2 g @ 76.1% HPLC purity.

[0229] Test 2 4,5-Dimethoxy-2-[(4-methoxyphenyl)thio]benzoic acid, first crop (5 g, 0.0156 mol) was added with stirring to 95% sulfuric acid (50 ml) and the mixture was stirred at room temperature overnight. TLC showed the reaction was complete so the reaction mixture was poured onto ice (300 g). The product was extracted with ethyl acetate (3 x 200 ml) and the combined organic extracts were washed with 10% potassium hydroxide solution (2 x 100 ml), then dried over sodium sulfate and filtered. The solvent was removed under reduced pressure leaving a pale yellow solid, 0.5 g @ 85.1% purity by HPLC.

[0230] The two products were combined and dissolved in tetrahydrofuran (250 ml) then stirred with 10% potassium hydroxide solution (150 ml). The two layers were separated and the aqueous phase was extracted with ethyl acetate (2 x 100 ml). The combined organics were dried over sodium sulfate, filtered and concentrated to a yellow solid. This was dissolved in refluxing toluene (70 ml) and hot filtered through a GF / F fibre pad. After cooling to room temperature overnight no solids were present. The solution was concentrated to approximately 1 / 3 volume and allowed to cool. The solid was collected by filtration, washed with t-butyl methyl ether and dried to give 690 mg @ 93.43%.

[0231] The UV absorption spectrum of this compound is shown in FIG.

[0232] Example 11 Synthesis of 3,4-bis(benzyloxy)-9H-thioxanthen-9-one To a solution of 3,4-dihydroxy-9H-thioxanthen-9-one (34 g, 0.139 mol) in acetone (850 ml) was added anhydrous potassium carbonate (119 g, 0.861 mol, 6.2 equiv.) under a nitrogen atmosphere.

[0233] The mixture was heated to reflux and benzyl chloride (60 g, 0.474 mol, 3.4 equiv) was added dropwise over approximately 2 hours. The reaction was then refluxed overnight (approximately 18 hours). The reaction was checked by TLC (1:1 hexanes / ethyl acetate) and found to be nearly complete. An additional 5 g of benzyl chloride was added and the reaction was refluxed for an additional 2 hours, after which the reaction was complete.

[0234] The reaction mixture was cooled to room temperature then poured into demineralised water (5.1 lt) and stirred for 10 minutes. The resulting solid was collected by filtration, washed on the filter with demineralised water (~1 lt) and then barrier washed with hexane (~500 ml). The off-white solid was stirred with ethanol (200 ml) for 10 minutes, again collected by filtration, dried and washed with t-butyl methyl ether. The solid was dried to constant weight.

[0235] The yield was 54 g, 0.127 mol, 91.4%, and the purity by HPLC was 99.24%.

[0236] Example 13 Synthesis of 3,4-bis(1-ethoxyethyl)-9H-thioxanthen-9-one 3,4-Dihydroxy-9H-thioxanthen-9-one (5 g, 20.5 mmol) was suspended in diethyl ether (50 ml) under a nitrogen atmosphere, to which was added ethyl vinyl ether (7.4 g, 102.5 mmol, 5 equiv.) and trifluoroacetic acid (0.24 g, 2.05 mmol).

[0237] The mixture was stirred at ambient temperature for 4 days. The mixture was still a suspension and TLC showed starting material was still present, so tetrahydrofuran (25 ml) was added (did not dissolve), and ethyl vinyl ether (10 g, 139 mmol) and 10 drops of trifluoroacetic acid were added.

[0238] The reaction was stirred for an additional 24 hours and then found to be in solution and all starting material had been consumed. Two top spots were present and an additional charge of ethyl vinyl ether (7.4 g, 102.5 mmol) was added and the reaction was stirred for an additional 24 hours without modification.

[0239] The reaction mixture was neutralized by the addition of triethylamine (~0.5 ml) and stirred for an additional hour. The reaction mixture was filtered through a GF / F fiber pad to remove traces of insoluble material. The reaction mixture was concentrated to a thick brown syrup and traces of solvent were blown off with nitrogen.

[0240] Yield: 7g per sample 1 HNMR was performed and showed the correct product was present (along with some minor impurities and solvent residues).

[0241] Example 14 Synthesis of 3',4'-dimethoxyspiro[(1,3)-dioxane-2,9'-thioxanthene] Stage I: 3,4-dimethoxy-9H-thioxanthene-9-thione 3,4-Dimethoxy-9H-thioxanthen-9-one (10 g, 36.7 mmol) was suspended in toluene (300 ml) and Lawesson's reagent (11 g, 27.2 mmol) was added to it. The mixture was heated to 80° C. under nitrogen atmosphere and followed by TLC. The reaction was complete within 1 hour.

[0242] The reaction was cooled to room temperature and poured into water (1000 ml), the toluene layer separated and the aqueous layer extracted with ethyl acetate (3 x 300 ml). The combined organic extracts were washed with brine (500 ml) and dried over sodium sulfate. The drying agent was removed by filtration and the solvent removed in vacuo to leave a dark green solid. This was triturated with t-butyl methyl ether, collected by filtration and washed with several ml of t-butyl methyl ether.

[0243] The green solid was allowed to dry in air leaving 9 g, 85%, 94.71% pure by HPLC.

[0244] Stage II: 3',4'-dimethoxyspiro[(1,3)-dioxane-2,9'-thioxanthene] 3,4-Dimethoxy-9H-thioxanthene-9-thione (9 g, 31.2 mmol) was suspended in acetonitrile (200 ml).

[0245] Under a nitrogen atmosphere, 1,3-propanediol (3.3 g, 43.4 mmol) and triethylamine (17 ml) were added. The mixture was stirred and silver trifluoroacetate (26.1 g) was added. A color change from green to red occurred and an increase in temperature (13.8-25.6 °C) was observed. After 1 h, TLC (2:1 hexane / ethyl acetate) showed no starting material remaining and two product spots (GC, 68.86% and 26.78% corresponding to the parent ketone).

[0246] The acetonitrile was evaporated and the residue was partitioned between brine (200 ml) and ethyl acetate (200 ml) then filtered through GF / F to remove inorganics. The filter cake was washed with ethyl acetate (2×100 ml). The two layers were separated and the aqueous layer was extracted with ethyl acetate (2×100 ml). The combined organic extracts were dried over sodium sulfate and then filtered to remove the drying agent.

[0247] The clear solution was concentrated to leave an orange / brown solid, 9 g.

[0248] This was dissolved in isopropyl alcohol (260 ml) and sodium borohydride (8 g, 211 mmol) was added and the reaction stirred overnight at 50° C. under nitrogen. GC showed 6.15% ketone and 19.65% alcohol present so the reaction was cooled to room temperature and poured into saturated brine (400 ml). The product was extracted with ethyl acetate (3×300 ml) and the combined organic extracts were dried over sodium sulfate, filtered and concentrated to a white solid, 5 g. This was recrystallized from ethanol (80 ml) and allowed to cool in the refrigerator for several hours. The solid was collected by filtration and washed on the filter with a small amount of ethanol and t-butyl methyl ether. The solid was dried in a vacuum oven at 50° C.

[0249] The yield was 4.4 g, 42.7%. The purity was 97.8% by GC and 98.94% by HPLC. The product was 1 1 H NMR was consistent with the structure.

[0250] Example 15 Synthesis of di-t-butyl (9-thioxo-9H-thioxanthene-3,4-diyl) dicarbonate Stage I: Di-t-butyl (9-oxo-9H-thioxanthene-3,4-diyl) dicarbonate 3,4-Dihydroxy-9H-thioxanthen-9-one (5 g, 20.5 mmol) was suspended in acetonitrile (50 ml) and stirred under nitrogen. To this was added di-t-butyl dicarbonate (11.2 g, 51.3 mmol), and 4-dimethylaminopyridine (1.25 g, 10.25 mmol). The mixture was stirred at room temperature and followed by TLC. Vigorous effervescence occurred initially, followed by dissolution of the solids to give a dark brown solution. A later TLC (1:1, hexane / ethyl acetate) showed the reaction was complete after 30 min. The reaction mixture was filtered through GF / F and the solvent removed leaving a thick syrup which was triturated / crystallized from ethanol. The solid was collected by filtration, washed on the filter with ethanol and t-butyl methyl ether, and dried to give 4 g which was used immediately in the next step.

[0251] Stage II: Di-t-butyl (9-thioxo-9H-thioxanthene-3,4-diyl) dicarbonate The above crude product (4 g, 9 mmol) was dissolved in toluene (80 ml) and Lawesson's reagent (2.6 g) was added to it. The mixture was heated at 80° C. for 30 minutes under nitrogen atmosphere. TLC (2:1 hexane / ethyl acetate) showed the reaction was complete.

[0252] The reaction mixture was cooled to room temperature and poured into saturated sodium bicarbonate solution (200 ml). The organic layer was separated, the aqueous layer extracted with ethyl acetate (2 x 100 ml) and the combined organic extracts washed with brine (200 ml). The extracts were dried over sodium sulfate, filtered through a GF / F fibre pad and the solvent removed in vacuo to leave a green oil (assumed to be 9 mmol) which was used directly in the next step below.

[0253] Stage: III: Di-t-butylspiro[(1,3)-dioxolane-2,9'-thioxanthene]-3',4'-diyldicarbonate.

[0254] The di-t-butyl (9-thioxo-9H-thioxanthene-3,4-diyl) dicarbonate from above (assumed to be 9 mmol) was dissolved in acetonitrile (80 ml) under a nitrogen atmosphere. To this was added ethylene glycol (1 g, 16 mmol) and triethylamine (6 ml), followed by silver trifluoroacetate (7.6 g). The mixture was stirred at ambient temperature for 1 hour and then checked by TLC (2:1, hexane / ethyl acetate), which showed completion.

[0255] The acetonitrile was evaporated and the residue was partitioned between brine (200 ml) and ethyl acetate (200 ml). The mixture was filtered through GF / F and separated. The aqueous layer was extracted with ethyl acetate (2×50 ml) and the organic layer was dried over sodium sulfate.

[0256] The solvent was removed and the resulting brown residue was purified on a "Jones" column.

[0257] This gave 1.8 g of material, which was 1 1 H NMR was taken and was consistent with the expected structure but contained residual solvent which was removed under high vacuum.

Claims

1. Compounds of Formula I: 【Chemistry 1】 wherein n is 1, 2, 3, 4 or 5; or Compound of formula (Ia): 【Chemistry 2】 wherein R is methyl, ethyl or propyl; In the compounds of formula (I) and formula (Ia) above, one of the aromatic rings is substituted with at least two substituents independently selected from hydroxy, alkoxy, benzyloxy, C1-4 alkyl carbonate, hydroxyalkyl, C1-4 alkoxyalkyl, C1-4 alkyl acid ester, oxyacetic acid and its ester, aryloxy and arylthio, and / or adjacent carbon atoms of said one of the aromatic rings are each bonded to an oxygen atom to form a 5-membered cyclic orthoester, the other aromatic ring is unsubstituted or substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, C1-4 alkylcarbonate, hydroxyalkyl, C1-4 alkoxyalkyl, C1-4 alkyl acid ester, oxyacetic acid and its esters, aryloxy, and arylthio, or adjacent carbon atoms of said other aromatic ring are each bonded to an oxygen atom to form a 5-membered cyclic orthoester; and In the compound of formula (I) above, the 1,3-dioxolane ring, 1,3-dioxane ring, 1,3-dioxepane ring, 1,3-dioxocane ring or 1,3-dioxonane ring is unsubstituted or substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl, or vinyl.

2. said one aromatic ring is substituted with three or four substituents independently selected from hydroxy, alkoxy, benzyloxy, C1-4 alkyl carbonate, hydroxyalkyl, C1-4 alkoxyalkyl, C1-4 alkyl acid ester, oxyacetic acid and its esters, aryloxy and arylthio; or The compound according to claim 1, wherein two adjacent carbon atoms of said one aromatic ring are each bonded to an oxygen atom to form a 5-membered cyclic orthoester, and said one aromatic ring is further substituted with one or two substituents independently selected from hydroxy, alkoxy, benzyloxy, C1-4 alkylcarbonate, hydroxyalkyl, C1-4 alkoxyalkyl, C1-4 alkyl acid ester, oxyacetic acid and its esters, aryloxy, and arylthio.

3. each independently, alkoxy is C1-4 alkoxy; hydroxyalkyl is a hydroxy(C1-4)alkyl group; The C1-4 alkyl carbonate is t-butyl carbonate; the C1-4 alkyl acid ester is an acetate ester; the cyclic orthoester is methyl orthoformate, ethyl orthoformate, n-propyl orthoformate, or isopropyl orthoformate; The compound according to claim 1 or 2, wherein the C1-4 alkoxyalkyl is ethoxyethyl.

4. The compound of any one of claims 1 to 3, wherein the substituents on the aromatic ring are selected from hydroxy and alkoxy.

5. 5. The compound of formula (I) according to any one of claims 1 to 4, wherein the 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane or 1,3-dioxonane ring is substituted with one or more substituents selected from alkyl, cycloalkyl, chloroalkyl, aryl or vinyl.

6. A compound selected from the following: 3',4'-dimethoxyspiro[1,3-dioxane-2,9'-thioxanthene], 3',4'-dimethoxyspiro[1,3-dioxolane-2,9'-thioxanthene], 2',3'-dimethoxyspiro[(1,3)-dioxolane-2,9'-thioxanthene], methane; 2'-methoxy-5,6-dimethyl-spiro[1,3-dioxepane-2,6'-thiochromeno[3,2-g][1,3]benzodioxane 2'-Methoxyspiro[1,3-dioxane-2,6'-thiochromeno[3,2-g][1,3]benzodioxole], 2'-Methoxyspiro[1,3-dioxane-2,6'-thiochromeno[2,3-g][1,3]benzodioxole], 2'-Methoxy-5,5-dimethyl-spiro[1,3-dioxane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-Methoxy-4,6-dimethyl-spiro[1,3-dioxane-2,6'-thiochromeno[3,2-g][1,3]benzodioxole], 2'-Methoxy 2'-methoxy-4,7-dimethyl-spiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-methoxy-5,5-dimethyl-spiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-methoxy-5-methyl-spiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-ethoxyspiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-ethoxyspiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], -propoxyspiro[1,3-dioxepane-2,6'-thiochromeno[3,2-g][1,3]benzodioxole], 2'-phenoxyspiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-isopropoxyspiro[1,3-dioxepane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-ethoxyspiro[1,3-dioxane-2,6'-thiochromeno[3,2-g][1,3]benzodioxole], 2'-ethoxyspiro[1,3-dioxolane-2 ,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-propoxyspiro[1,3-dioxane-2,6'-thiochromeno[3,2-g][1,3]benzodioxole], 2'-propoxyspiro[1,3-dioxolane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-isopropoxyspiro[1,3-dioxane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-isopropoxyspiro[1,3-dioxane-2,6'-thiochromeno[3,2-g][1,3] benzodioxole], 2'-methoxyspiro[1,3-dioxane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], 2'-methoxyspiro[1,3-dioxolane-2,6'-thiochromeno[2,3-e][1,3]benzodioxole], spiro[1,3-dioxolane-2,9'-thioxanthene]-3',4'-diol, spiro[1,3-dioxane-2,9'-thioxanthene]-3',4'-diol, spiro[1,3-dioxane-2,9'-thioxanthene]-3',4'-diol, 5-methylspiro[1,3-dioxepane-2,9'-thioxanthene]-3' ,4'-diol, 5,5-dimethylspiro[1,3-dioxepane-2,9'-thioxanthene]-3',4'-diol, 3',4'-dimethoxy-4,6-dimethyl-spiro[1,3-dioxane-2,9'-thioxanthene], 3',4'-dimethoxy-4,5-dimethyl-spiro[1,3-dioxolane-2,9'-thioxanthene], 9,9-diethoxy-3,4-dimethoxy-thioxanthene, 2-methoxy-6,6-dipropoxy-thiochromeno[3,2-g][1,3]benzodioxole, and 6,6-diethoxy-2-methoxy-thiochromeno[2,3-e][1,3]benzodioxole.

7. (a) a compound of formula (I) or (Ia) according to any one of claims 1 to 5; and (b) a chemically convertible substrate; A composition comprising: The compound of formula (I) or (Ia) can be reacted in the presence of an acid to give a reactive derivative of formula (II): 【Chemistry 3】 wherein one aromatic ring is substituted with at least two substituents independently selected from hydroxy, alkoxy, benzyloxy, C1-4 alkyl carbonate, hydroxyalkyl, C1-4 alkoxyalkyl, C1-4 alkyl acid ester, oxyacetic acid and its esters, aryloxy and arylthio, and / or adjacent carbon atoms of said one aromatic ring are each bonded to an oxygen atom to form a five-membered cyclic orthoester; the other aromatic ring is unsubstituted or substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, C1-4 alkylcarbonate, hydroxyalkyl, C1-4 alkoxyalkyl, C1-4 alkyl acid ester, oxyacetic acid and its ester, aryloxy and arylthio, or adjacent carbon atoms of said other aromatic ring are each bonded to an oxygen atom to form a 5-membered cyclic orthoester; and The composition, wherein said chemically convertible substrate can be converted by direct or indirect photoinitiation in the presence of a reactive derivative of formula (II).

8. 8. The composition of claim 7, wherein, independently, each of the alkoxy groups is a C1-4 alkoxy group and each of the hydroxyalkyl groups is a hydroxy(C1-4)alkyl group.

9. 9. The composition according to claim 7 or 8, wherein the convertible substrate is a substrate capable of cationic polymerization or a substrate capable of free radical-promoted polymerization, or the convertible substrate is a protected polymer having polar groups protected by acid labile groups, the polymer being soluble in the development medium after removal of the acid labile groups.

10. The composition of any one of claims 7 to 9, further comprising a photoacid generator (PAG).

11. The composition of claim 10 , wherein the PAG can be photosensitized by the compound of formula (II) and / or further comprises a quencher, or a photodegradable version thereof.

12. (a) forming a layer of the composition according to any one of claims 7 to 11 on a support; (b) applying an acid or generating an acid in situ to the predetermined areas of said layer and reacting said acid with a compound of Formula I or Formula Ia to form a reactive derivative of Formula II in the predetermined areas of said layer; (c) exposing the layer, with the reactive derivative present in the predetermined areas, to electromagnetic radiation of a wavelength or energy suitable to generate a reactive species from a compound of formula II; and (d) causing the reactive species to directly or indirectly convert the chemically convertible substrate; 23. A light initiation method comprising:

13. The composition comprises a PAG, and 13. The method of claim 12, wherein in (b), an acid is generated in situ by exposing the layer to an external stimulus, thereby causing the PAG to generate acid in predetermined regions of the layer for reaction with a compound of Formula I or Formula Ia.

14. 14. The method of claim 13, wherein the reactive species produced are free radicals and the chemically transformable substrate is a substrate capable of free radical-promoted polymerization, and the free radical reactive species directly causes conversion of the chemically transformable substrate.

15. 14. The method of claim 13, wherein the composition further comprises a coinitiator or synergist, and the reactive species generated is an excited state of a compound of formula II that can function as a sensitizer to activate the coinitiator or synergist, or the chemically convertible substrate is a protected polymer having a polar group protected by an acid labile group, and the reactive species generated is an excited state of a compound of formula II that can function as a sensitizer to activate the PAG, and deprotection of the protected polymer generates additional acid effective to convert the chemically convertible substrate.

16. A substrate; A layer of the composition according to any one of claims 7 to 11 formed on the substrate; a photoresist structure comprising:

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