Organic photocatalyst and production method for same

Abstract

Provided is an organic photocatalyst that includes a compound represented by formula (1). The organic photocatalyst can use visible light from a blue LED or the like as a light source, has excellent stability under photoirradiation, can be recycled without losing catalytic activity, and can be used for large-scale synthesis. (In formula (1), R1–R11 are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heterocyclic aromatic group, or a halogen atom (excluding R1, R6, and R9 being a hydrogen atom), R1 and R2, R2 and R3, R3 and R4, R4 and R5, R5 and R6, R6 and R7, R8 and R9, or R9 and R10 may form a ring structure, X is a nitrogen atom or a boron atom, and Y and Z are each independently a sulfur atom, an oxygen atom or -NR12- (R12 being an alkyl group or an aryl group).)

Description

Organic photocatalyst and method for producing the same

[0001] The present invention relates to an organic photocatalyst and a method for producing the same.

[0002] Photocatalyst recycling has attracted much attention from the perspectives of environmental issues and economic benefits. Homogeneous photocatalysts, such as polypyridyl complexes of ruthenium and iridium, and organic dyes, are widely used in photoredox catalysis. While recycling of metal-containing photoredox catalysts is well known, recycling of organic photoredox catalysts has not yet been extensively studied. Because organic photoredox catalysts are cost-effective and have low toxicity, the development of recyclable organic photoredox catalysts is an important challenge for developing sustainable organic synthesis reactions.

[0003] For example, PTH-1 (10-phenylphenothiazine) represented by the following formula is widely used as a photocatalyst for photoredox catalytic reactions and atom transfer radical addition polymerization (Non-Patent Document 1). PTH-1 has a high reducing power (E １／２ ｏｘ＊ = -2.10 vs. SCE), many photoredox catalytic reactions have been developed that proceed via an oxidative quenching cycle. Recently, several phenothiazine catalysts, such as PTH-2, PTH-3, and PTH-4, which are represented by the following formulas and are modifications of the PTH-1 structure, have been reported (Non-Patent Documents 2 to 4). However, phenothiazine catalysts such as PTH-1 have a problem in that the p-position of the nitrogen atom is highly reactive, and the catalyst decomposes when reacting with electrophiles, and the development of a more stable organic photocatalyst has been desired.

[0004]

[0005] Lee, Y. et al., Eur. J. Org. Chem. 2020, 38, 6028-6043Zhao, Y. et al., Macromolecules 2018, 51, 938-946Shibutani, S. et al., J. Am. Chem. Soc. 2020, 142, 1211-1216D. M. Fischer et al., J. Am. Chem. Soc. 2023, 145, 774-780

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide an organic photocatalyst that can use visible light from a blue LED or the like as a light source, has excellent stability under light irradiation, is recyclable without losing catalytic activity, and is applicable to mass synthesis.

[0007] The above problem can be solved by providing an organic photocatalyst containing a compound represented by the following formula (1):

[0008] [In formula (1), R １ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom (provided that R １ , R ６ and R ９ is a hydrogen atom), R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ may form a ring structure, X is a nitrogen atom or a boron atom, and Y and Z are each independently a sulfur atom, an oxygen atom, or —NR １２ - (R １２ is an alkyl group or an aryl group).

[0009] The above problem can also be solved by providing an organic photocatalyst containing a compound represented by the following formula (2):

[0010] [In formula (2), R １ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom (provided that R １ , R ６ and R ９ is a hydrogen atom), R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ may form a ring structure.]

[0011] A preferred embodiment is an organic photocatalyst containing a compound represented by the following formula (2x):

[0012] [In formula (2x), R １ , R ６ and R ９ are each independently an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom.

[0013] A preferred embodiment is an organic photocatalyst containing a compound represented by the following formula (2a), (2b) or (2c):

[0014]

[0015]

[0016]

[0017] There is preferably provided a method for producing an organic photocatalyst containing a compound represented by the above formula (2), which comprises reacting a cyclohexanone derivative represented by the following formula (3), an ammonium halide, and elemental sulfur.

[0018] [In formula (3), R １ ~R １１ has the same meaning as the formula (2).

[0019] Also provided is a method for producing an organic photocatalyst containing a compound represented by the above formula (2), which comprises reacting a triphenylamine derivative represented by the following formula (4) with phthalimidosulfenyl halide to obtain a thiophthalamide compound, and then reacting the thiophthalamide compound with an aluminum halide.

[0020] [In formula (4), R １ ~R １１ has the same meaning as the formula (2).

[0021] The present invention provides an organic photocatalyst that can utilize visible light from a blue LED or the like as a light source, has excellent stability under light irradiation, is recyclable without losing catalytic activity, and is applicable to mass synthesis. The organic photocatalyst of the present invention has high reducing power and can therefore promote photocatalytic reactions that have been difficult to carry out until now.

[0022] PTHS-1 obtained in Synthesis Example 1 １ 1 H NMR spectrum of PTHS-2 obtained in Synthesis Example 2. １ 1 H NMR spectrum of PTHS-2 obtained in Synthesis Example 2. １３ 1 is a C NMR spectrum of the bis-N-thiophthalimide obtained in Synthesis Example 3. １ 1 H NMR spectrum of PTHS-3 obtained in Synthesis Example 3. １1H NMR spectrum. ... １ 1H NMR spectrum of the product obtained using the organic photocatalyst of the present invention in Example 2. １ 1H NMR spectrum of the product obtained using the organic photocatalyst of the present invention in Example 3. １ 1H NMR spectrum of the product obtained using the organic photocatalyst of the present invention in Example 4. １ 1 H NMR spectrum of the product obtained using PTH-1 in Comparative Example 1. １ 1 H NMR spectrum.

[0023] According to the present invention, an organic photocatalyst containing a compound represented by formula (1) can be provided. As a preferred embodiment of the compound represented by formula (1), a compound represented by formula (2) can be provided. As a preferred embodiment of the compound represented by formula (2), a compound represented by formula (2x) can be provided. Furthermore, as a preferred embodiment of the compound represented by formula (2), a compound represented by formula (2a), a compound represented by formula (2b), or a compound represented by formula (2c) can be provided.

[0024] [In formula (1), R １ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom (provided that R １ , R ６ and R ９ is a hydrogen atom), R １ and R ２ , R ２ and R ３ , R ３ and R４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ may form a ring structure, X is a nitrogen atom or a boron atom, and Y and Z are each independently a sulfur atom, an oxygen atom, or —NR １２ - (R １２ is an alkyl group or an aryl group).

[0025] [In formula (2), R １ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom (provided that R １ , R ６ and R ９ is a hydrogen atom), R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ may form a ring structure.]

[0026] [In formula (2x), R １ , R ６ and R ９ are each independently an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom.

[0027]

[0028]

[0029]

[0030] As represented by the above formulas (1), (2), (2x), and (2a) to (2c), the organic photocatalyst of the present invention has an extended π-conjugated system due to a helical structure bridged by Y, such as a sulfur atom, and can utilize visible light from a blue LED or the like as a light source. As will be seen from the examples and comparative examples described below, the photocatalytic reaction did not proceed without the addition of a catalyst or without irradiation with a blue LED, and the photocatalytic reaction hardly proceeded when the conventional phenothiazine catalyst PTH-2 was used. When catalyst recycling was investigated, the conventional phenothiazine catalyst PTH-1 was found to have a reduced yield and lost catalytic activity with repeated use. Furthermore, in photochemical sulfonylation reactions, the catalyst PTH-1 reacted with TsCl under light irradiation, resulting in a loss of catalytic activity. In contrast, the inventors' studies have revealed that the organic photocatalyst of the present invention has a high reducing power, allowing the photocatalytic reaction to proceed with good yield, is recyclable even after repeated use without losing catalytic activity, and exhibits excellent stability by not reacting with TsCl under light irradiation. As described above, the organic photocatalyst of the present invention exhibits a remarkable effect compared to the conventional phenothiazine catalyst, and it is clear that the present invention is of great significance.

[0031] In the above formulas (1) and (2), R １ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom (provided that R １ , R ６ and R ９ is a hydrogen atom), R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R１０ may form a ring structure. １ , R ６ and R ９ It has been found that when R is a hydrogen atom, the stability of the organic photocatalyst is poor. １ , R ６ and R ９ are not hydrogen atoms but are independently an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom; R ２ ~R ５ , R ７ ~R ８ , and R １０ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom; R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ In particular, the present inventors have found that by introducing a bulky substituent into the p-position of X in the above formula (1) and the p-position of the nitrogen atom in the above formula (2), the catalyst has high reducing power and excellent stability as a catalyst. １ , R ６ and R ９ are each independently an alkyl group, typified by a tert-butyl group, an aryl group, an aryloxy group, or a heteroaromatic ring group. ２ ~R ５ , R ７ ~R ８ , and R １０ ~R１１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom; R ２ and R ３ , R ３ and R ４ In a preferred embodiment, the structure may form a ring structure.

[0032] R １ ~R １１ The alkyl group used in may be a straight-chain or branched-chain alkyl group, or a cyclic cycloalkyl group. Examples include straight-chain or branched-chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, isohexyl, 2-ethylhexyl, n-heptyl, n-octyl, 2-butyloctyl, n-nonyl, and n-decyl; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptanyl, cyclooctanyl, cyclononanyl, and cyclodecanyl. Among these, alkyl groups having 1 to 12 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, and alkyl groups having 1 to 8 carbon atoms are even more preferred. From the viewpoint of having a high reducing power and excellent stability as a catalyst, an alkyl group which is a bulky substituent having 4 to 8 carbon atoms is preferred, and for example, a sec-butyl group, a tert-butyl group, a cyclohexyl group, an n-heptyl group, etc. are particularly suitable.

[0033] The alkyl group may have other substituents, and examples of such other substituents include aryl groups such as a phenyl group and a naphthyl group; heteroaromatic groups such as a pyridyl group, a thienyl group, a furyl group, a pyrrolyl group, an imidazolyl group, a pyrazinyl group, an oxazolyl group, a thiazolyl group, a pyrazolyl group, a benzothiazolyl group and a benzimidazolyl group; methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, alkoxy groups such as an isopentyloxy group, a neopentyloxy group, a hexyloxy group, a cyclohexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, or a dodecyloxy group; alkylthio groups such as a methylthio group, an ethylthio group, a propylthio group, or a butylthio group; arylthio groups such as a phenylthio group or a naphthylthio group; tri-substituted silyloxy groups such as a tert-butyldimethylsilyloxy group or a tert-butyldiphenylsilyloxy group; an acetoxy group, acyloxy groups such as a propanoyloxy group, a butanoyloxy group, a pivaloyloxy group, and a benzoyloxy group; alkoxycarbonyl groups such as a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, a butoxycarbonyl group, an isobutoxycarbonyl group, a sec-butoxycarbonyl group, a tert-butoxycarbonyl group, a pentyloxycarbonyl group, a hexyloxycarbonyl group, a heptyloxycarbonyl group, and an octyloxycarbonyl group; alkylsulfinyl groups such as a methylsulfinyl group and an ethylsulfinyl group; arylsulfinyl groups such as a phenylsulfinyl group; sulfonate groups such as a methylsulfonyloxy group, an ethylsulfonyloxy group, a phenylsulfonyloxy group, a methoxysulfonyl group, an ethoxysulfonyl group and a phenyloxysulfonyl group; an amino group; a hydroxyl group; a cyano group; a nitro group; and halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0034] R １ ~R １１Examples of the aryl group used in the formula (1) include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Among these, an aryl group having 6 to 14 carbon atoms is preferred, and an aryl group having 6 to 10 carbon atoms is more preferred. These aryl groups may have other substituents, and as such other substituents, the same substituents as those exemplified in the description of the alkyl group can be used.

[0035] R １ ~R １１ Examples of the alkoxy group used in include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentyloxy group, an isopentyloxy group, a neopentyloxy group, an n-hexyloxy group, an isohexyloxy group, a 2-ethylhexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, and an n-decyloxy group. Among these, an alkoxy group having 1 to 10 carbon atoms is preferred, an alkoxy group having 1 to 8 carbon atoms is more preferred, and an alkoxy group having 1 to 6 carbon atoms is even more preferred. These alkoxy groups may have other substituents, and as such other substituents, the same substituents as those exemplified in the description of the alkyl group can be used.

[0036] R １ ~R １１ Examples of the aryloxy group used in the above formula include a phenoxy group, a naphthyloxy group, an anthryloxy group, and a phenanthryloxy group. Among these, an aryloxy group having 6 to 14 carbon atoms is preferred, and an aryloxy group having 6 to 10 carbon atoms is more preferred. These aryloxy groups may have other substituents, and as such other substituents, the same substituents as those exemplified in the description of the alkyl group can be used.

[0037] R １ ~R １１ The amino group used in the ２ ), a secondary amino group or a tertiary amino group may also be used. １３ (R １３is an arbitrary monovalent substituent), and R １３ Examples of the secondary amino group include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an acetyl group, a benzoyl group, a benzenesulfonyl group, a tert-butoxycarbonyl group, etc. Specific examples of the secondary amino group include R , such as a methylamino group, an ethylamino group, a propylamino group, an isopropylamino group, etc. １３ R is a secondary amino group in which R is an alkyl group, a phenylamino group, a naphthylamino group, etc. １３ and a secondary amino group in which R is an aryl group. １３ The hydrogen atom of the alkyl group or aryl group in the formula (I) may be further substituted with an acetyl group, a benzoyl group, a benzenesulfonyl group, a tert-butoxycarbonyl group, etc. The tertiary amino group is represented by the formula (I) -NR １３ R １４ (R １３ and R １４ is an arbitrary monovalent substituent), and R １４ As for R １３ can be used, and R １３ and R １４ may be the same or different. Specific examples of the tertiary amino group include a dimethylamino group, a diethylamino group, a dibutylamino group, an ethylmethylamino group, a diphenylamino group, and a methylphenylamino group. １３ and R １４ is at least one selected from the group consisting of alkyl groups and aryl groups, and the like.

[0038] R １ ~R １１ Examples of the heteroaromatic ring group used in the above formula include a pyridyl group, a furyl group, a thienyl group, a pyrrolyl group, an imidazolyl group, a pyrazinyl group, an oxazolyl group, a thiazolyl group, a pyrazolyl group, a benzothiazolyl group, a benzimidazolyl group, etc. These heteroaromatic ring groups may have other substituents, and as such other substituents, the same substituents as those exemplified in the description of the alkyl group can be used.

[0039] R １~R １１ Examples of the halogen atom used include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Among these, at least one selected from the group consisting of a fluorine atom, a chlorine atom, and a bromine atom is preferably used.

[0040] In the above formulas (1) and (2), R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ may form a ring structure. ２ and R ３ , R ３ and R ４ , or R ４ and R ５ In a preferred embodiment, the ring structure may have another substituent, and as such another substituent, the same substituents as those exemplified in the description of the alkyl group can be used. The ring structure is preferably an aromatic ring, more preferably a benzene ring or a naphthalene ring, and even more preferably a benzene ring.

[0041] In the above formula (1), X is a nitrogen atom or a boron atom, and Y and Z are each independently a sulfur atom, an oxygen atom, or —NR １２ - (R １２ X, Y, and Z are such substituents, and thus the compound can be used as an organic photocatalyst with high reducing power. １２ -R １２ is an alkyl group or an aryl group, and R １ ~R １１The same substituents as those exemplified in the description of the alkyl group or aryl group used in (1) can be used. Among them, X is preferably a nitrogen atom, and Y and Z are each preferably independently a sulfur atom or an oxygen atom. The compound represented by the above formula (2) is a preferred embodiment.

[0042] Among the compounds represented by the above formulas (1) and (2), the compounds represented by the following formulas (2a), (2b) and (2c) are more preferred embodiments.

[0043]

[0044]

[0045]

[0046] The method for producing the organic photocatalyst of the present invention is not particularly limited, but a method of reacting a cyclohexanone derivative represented by the following formula (3), an ammonium halide, and elemental sulfur to obtain an organic photocatalyst containing a compound represented by the above formula (2) is preferably employed.

[0047] [In formula (3), R １ ~R １１ has the same meaning as the formula (2).

[0048] In the cyclohexanone derivative represented by the above formula (3), R １ ~R １１ The substituents may be the same as those exemplified in the explanation of the formula (2) above. As the ammonium halide, ammonium fluoride (NH ４ F), ammonium chloride (NH ４ Cl), ammonium bromide (NH ４ Br), ammonium iodide (NH ４I), and the like, among which at least one selected from the group consisting of ammonium chloride, ammonium bromide, and ammonium iodide is preferably used. As described in the Examples below, for example, in Synthesis Example 1 using 4-tert-butylcyclohexanone as the cyclohexanone derivative represented by formula (3) above, and Synthesis Example 2 using 4-heptylcyclohexanone, the cyclohexanone derivative, an ammonium halide such as ammonium iodide, and elemental sulfur are reacted to obtain the compound represented by formula (2a) or (2b).

[0049] Furthermore, as a method for producing the organic photocatalyst of the present invention, a method is also suitably adopted in which a triphenylamine derivative represented by the following formula (4) is reacted with phthalimidosulfenyl halide to obtain a thiophthalamide compound, and then the obtained compound is reacted with aluminum halide to obtain an organic photocatalyst containing the compound represented by the above formula (2).

[0050] [In formula (4), R １ ~R １１ has the same meaning as the formula (2).

[0051] In the triphenylamine derivative represented by the above formula (4), R １ ~R １１ In order to obtain a thiophthalamide compound by bonding phthalimidosulfenyl halide, R in the triphenylamine derivative represented by the above formula (4) can be the same as the substituents exemplified in the description of the above formula (2). ４ is preferably a hydrogen atom. Among these, a more preferred embodiment is a method of reacting a triphenylamine derivative represented by the following formula (4a) with phthalimidosulfenyl halide to obtain a thiophthalamide compound.

[0052] [In formula (4a), R １ , R ６ and R ９ has the same meaning as the formula (2).

[0053] Examples of the phthalimidosulfenyl halide include phthalimidosulfenyl fluoride, phthalimidosulfenyl chloride, phthalimidosulfenyl bromide, and phthalimidosulfenyl iodide. Among these, at least one selected from the group consisting of phthalimidosulfenyl chloride and phthalimidosulfenyl bromide is preferably used. Examples of the aluminum halide include aluminum fluoride (AlF ３ ), aluminum chloride (AlCl ３ ), aluminum bromide (AlBr ３ ), aluminum iodide (AlI ３ Among them, at least one selected from the group consisting of aluminum chloride and aluminum bromide is preferably used. As described in the Examples below, for example, in Synthesis Example 3 in which tris(4-methoxyphenyl)amine is used as the triphenylamine derivative represented by the above formula (4), the triphenylamine derivative is reacted with a phthalimidosulfenyl halide such as phthalimidosulfenyl chloride to obtain a thiophthalamide compound, and then the obtained thiophthalamide compound is reacted with an aluminum halide such as aluminum chloride to obtain the compound represented by the above formula (2c).

[0054] The organic photocatalyst of the present invention has a high reducing power and is therefore capable of proceeding with photocatalytic reactions that have been difficult to carry out until now. In particular, it is capable of efficiently proceeding with photoredox reactions that involve one-electron reduction of a substrate. The organic photocatalyst of the present invention can also be suitably used for producing structural isomers at the ortho-, meta-, and para-positions. From this perspective, a preferred embodiment of the organic photocatalyst of the present invention is an organic one-electron reducing agent, and a preferred embodiment is also an organic photoredox catalyst.

[0055] The present invention will be explained in more detail below using examples. Commercially available reagents were used as they were. Heating reactions were carried out using an oil bath. Analytical thin-layer chromatography (TLC) was carried out using aluminum TLC plates (Merck TLC Silica Gel 60F254). Column chromatography was carried out using Kanto Chemical Silica Gel 60N (40-100 mesh, spherical, neutral). IR spectra were obtained using IRSpirit-T. １ H and １３ C NMR spectra were obtained using a Varian NMR System PS600 or a Varian 400MR ASW. Chemical shifts in NMR spectra are reported in ppm relative to the internal residual solvent ( １ H NMR, CDCl ３ 7.26 ppm, C ６ D ６ 7.16 ppm; １３ C NMR, CDCl ３ 77.0 ppm). The following abbreviations are used for couplings: s = singlet, d = doublet, t = triplet, m = multiplet, br = broad. High-resolution mass spectra were recorded on a Waters Micromass LCT (ESI-TOF-MS). UV-Vis absorption spectra were measured using a JASCO V-770 spectrometer. Fluorescence spectra were obtained using an RF-6000. Cyclic voltammetry measurements were performed using an ECstat-101. Photochemical reactions were performed using a photoreactor (EvoluChem™ PhotoRedOx Box) and a blue LED (HCK1012-01-012, 425 nm, 18 W).

[0056] Synthesis Example 1 [Synthesis of 3,7,11-tri-tert-butylbenzo[5,6][1,4]thiazino[2,3,4-kl]phenothiazine (PTHS-1) (Reference 1)]

[0057]

[0058] The reaction was carried out using ammonium iodide (362.3 mg, 2.5 mmol), sodium iodide (44.7 mg, 0.3 mmol), elemental sulfur (255.0 mg, 1.0 mmol), 4-tert-butylcyclohexanone (462.5 mg, 3.0 mmol), dimethyl sulfoxide (0.14 mL, 2.0 mmol), and ethyl acetate (3.0 mL). The residue was purified by silica gel column chromatography (hexane) to give the product as a yellow solid (225.6 mg, 48% yield). Figure 1 shows the structure of PTHS-1. １ The H NMR spectrum is shown. 1 H NMR (600 MHz, CDCl3) δ 7.20 (s, 2H), 7.13-7.12 (m, 4H), 6.97 (s, 2H), 1.29 (s, 18H), 1.24 (s, 9H).

[0059] Synthesis Example 2 [Synthesis of 3,7,11-tri-heptylbenzo[5,6][1,4]thiazino[2,3,4-kl]phenothiazine (PTHS-2)]

[0060]

[0061] The reaction was carried out using ammonium iodide (362.4 mg, 2.5 mmol), sodium iodide (44.50 mg, 0.3 mmol), elemental sulfur (255.2 mg, 1.0 mmol), 4-heptylcyclohexanone (0.67 mL, 3.0 mmol), dimethyl sulfoxide (0.14 mL, 2.0 mmol), and ethyl acetate (3.0 mL). The residue was purified by silica gel column chromatography (hexane) to give the product as a yellow liquid (185.3 mg, 31% yield). Figures 2 and 3 show the structure of PTHS-2. １ H NMR and １３ The C NMR spectra are shown below. f = 0.58 (hexane); IR (neat) 2955, 2925, 2854, 1490, 1451, 1323, 1313, 1130 cm -1 ; 1H NMR (600 MHz, CDCl3) δ 7.07 (d, J = 8.4 Hz, 2H), 7.00 (d, J = 2.4 Hz, 2H), 6.90 (dd, J = 8.4, 1.8 Hz, 2H), 6.78 (s, 2H), 2.52 (t, J = 7.2 Hz, 4H), 2.45 (q, J = 6.6 Hz, 2H), 1.59-1.51 (m, 6H), 1.32-1.27 (m, 24H), 0.90-0.86 (m, 9H); 13 C NMR (150 MHz, CDCl3) δ 140.4, 139.5, 139.2, 137.4, 127.4, 127.4, 126.4, 125.4, 125.3, 120.1, 35.1, 34.9, 31.8, 31.8, 31.4, 31.3, 29.2, 29.2, 29.1, 29.1, 22.7, 22.6, 14.1, 14.1; HRMS (ESI TOF) C 39 H 53 NS2 [M] + Calculated value: 599.3619, measured value: 599.3618.

[0062] Synthesis Example 3 [Synthesis of 3,7,11-tri-methoxy[5,6][1,4]thiazino[2,3,4-kl]phenothiazine (PTHS-3) (References 2, 3)]

[0063]

[0064] Tris(4-methoxyphenyl)amine (Reference 2) (346 mg, 1.03 mmol) in dry CHCl ３ (8.24 mL) solution was added phthalimidosulfenyl chloride (550 mg, 2.57 mmol) under Ar. After stirring at room temperature for 3.5 h, the reaction mixture was diluted with CH ２ Cl ２ Diluted with saturated NaHCO ３ The organic layer was washed with Na ２ SO ４The mixture was dried over 1000 kJ / ml, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (hexane / EtOAc = 3:1) to give bis-N-thiophthalimide as a yellow solid (647.5 mg, 91% yield). Figure 4 shows the bis-N-thiophthalimide. １ The H NMR spectrum is shown. 1 H NMR (600 MHz, CDCl3) δ 7.93 (dd, J = 5.4, 3.0 Hz, 4H), 7.79 (dd, J = 5.4, 3.0 Hz, 4H), 7.56 (d, J = 8.4 Hz, 2H), 6.82 (d, J = 9.0 Hz, 2H), 6.79 (dd, J = 9.0, 3.0 Hz, 2H), 6.76-6.75 (m, 2H), 6.56 (d, J = 3.0 Hz, 2H), 3.76 (s, 3H), 3.68 (s, 6H).

[0065] dryCH ２ Cl ２ (5.6 mL) was added bis-N-thiophthalamide (97.4 mg, 0.14 mmol), and the mixture was stirred under Ar with AlCl ３ (74.7 mg, 0.56 mmol) was added. After stirring at room temperature for 3 hours, the mixture was ２ Cl ２ Dilute with saturated Na ２ CO ３ The organic layer was washed with Na ２ SO ４ The mixture was dried over 1000 kJ / ml, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (hexane / EtOAc = 30:1 to 10:1) to give the phenothiazine catalyst as a dark yellow solid (42.8 mg, 77% yield). Figure 5 shows the structure of PTHS-3. １ The H NMR spectrum is shown. 1 H NMR (600 MHz, C6D6) δ 6.94 (d, J = 9.0 Hz, 2H), 6.74 (d, J = 2.4 Hz, 2H), 6.53 (s, 2H), 6.49 (dd, J = 9.0, 3.0 Hz, 2H), 3.20 (s, 6H), 3.09 (s, 3H).

[0066] [Evaluation of Redox Properties of PTHS-1, PTHS-2, and PTHS-3]

[0067]

[0068] The sample for electrochemical measurement was dry CH ２ Cl ２ The solution was prepared using 10 mL of 0.1 M tetrabutylammonium perchlorate solution in dry MeCN or dry MeCN and 0.1 mmol of substrate. Cyclic voltammetry measurements were performed using a computer-controlled potentiostat (ECstat-101, ECFRONTIER CO., LTD.). Cyclic voltammetry was performed using an undivided cell equipped with a working electrode (Pt disk electrode, φ3 mm), a counter electrode (Pt wire), and a reference electrode (Ag wire). Ferrocene / ferrocenium (Fc / Fc ＋ ) was measured in the same manner, and the apparent standard potential was used as the reference value for the electrode potential. ２ Cl ２ The excitation energy (E ０，０ ) to the ground-state oxidation potential (E １／２ (C ・＋ / C)) to obtain the excited oxidation potential (E １／２ (C ・＋ / C*) was calculated. ０，０ was determined by calculating the energy of the wavelength where the UV-Vis absorption spectrum and the emission spectrum overlap. The results are shown in Figures 6 to 8 and Table 1. These results indicate that the organic photocatalyst of the present invention has a higher reducing power than conventional phenothiazine catalysts and can therefore be used in various one-electron reduction reactions.

[0069]

[0070] Example 1 [Three-component oxytrifluoromethylation reaction of 1,1-diphenylethylene (Reference 4)]

[0071]

[0072]

[0073] In entry 1 of Table 2, Umemoto's reagent 1 (35.8 mg, 0.105 mmol), 1,1-diphenylethylene 2 (17.5 μL, 0.1 mmol), catalyst (1.0 mol%), acetone (1.8 mL), and H ２ 0 (0.2 mL) was added to a 4 mL vial. After bubbling with argon for 5 minutes, the mixture was stirred at room temperature for 2.5 hours under blue LED irradiation (λmax = 425 nm). The reaction mixture was added with saturated Na ２ SO ３ Add the aqueous solution and CH ２ Cl ２ The organic layer was extracted with Na ２ SO ４ The mixture was dried with hexane, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (hexane to hexane / EtOAc = 10:1) to give the desired product 3 as a pale yellow liquid. Entries 2 to 5 in Table 2 were also reacted under the conditions described in Table 2. Figure 9 shows the structure of product 3. １ The H NMR spectrum is shown. The reaction did not proceed efficiently in entry 4, where no catalyst was added, or entry 5, where no blue LED was irradiated, confirming that the organic photocatalyst of the present invention and the blue LED accelerated this reaction. 1 HNMR (600 MHz, CDCl3) δ 7.43-7.42 (m, 4H), 7.35-7.33 (m, 4H), 7.28-7.25 (m, 2H), 3.21 (q, J = 10.2 Hz, 2H), 2.64 (d, J = 1.2 Hz, 1H).

[0074] Example 2 [Decarboxylated C(sp ３ )-O bond forming reaction (Reference 5)]

[0075]

[0076]

[0077] In entry 1 of Table 3, ester 4 (Reference 6) (61.9 mg, 0.2 mmol), alcohol 5 (Reference 7) (153.2 mg, 0.6 mmol), catalyst (10 mol%), LiBF ４ (1.9 mg, 10 mol%) and MeCN (1.0 mL) were added to a 4 mL vial. After bubbling with argon for 5 minutes, the resulting solution was stirred at room temperature for 24 hours under blue LED irradiation (λmax = 425 nm). The reaction mixture was passed through a silica gel short-path column using diethyl ether and concentrated under reduced pressure. The residue was purified by flash chromatography (hexane / EtOAc = 20:1 to 10:1) to give the desired product 6 as a yellow liquid. Entries 2 to 5 in Table 3 were also reacted under the conditions described in Table 3. Figure 10 shows the structure of product 6. １ The H NMR spectrum is shown. The reaction did not proceed in entry 4, where no catalyst was added, or in entry 5, where no blue LED was irradiated, confirming that the organic photocatalyst of the present invention and the blue LED accelerated the reaction. 1 HNMR (400 MHz, CDCl3) δ 7.61 (d, J = 8.0 Hz, 2H), 7.39 (d, J = 7.2 Hz, 2H), 7.31-7.21 (m, 5H), 3.40- 3.34 (m, 2H), 3.20-3.14 (m, 1H), 2.56 (td, J = 10.4, 3.2 Hz, 2H), 2.43 (s, 3H), 1.72-1.58 (m, 4H), 1.49 (s, 6H).

[0078] Example 3 [Defluoroalkylation reaction of 1,3-bis(trifluoromethyl)benzene (Reference 8)]

[0079]

[0080]

[0081] For entry 1 in Table 4, 1,3-bis(trifluoromethyl)benzene 7 (15.3 μL, 0.1 mmol), 3-buten-1-ol (reference 8) (25.5 μL, 0.3 mmol), catalyst (10 mol%), sodium formate (20.4 mg, 0.3 mmol), and DMSO (1.0 mL) were added to a 4 mL vial. Cyclohexanethiol (1.2 μL, 0.01 mmol) was added to the solution, followed by bubbling with argon for 5 minutes. The resulting solution was stirred at room temperature for 72 hours under blue LED irradiation (λmax = 425 nm). The reaction mixture was diluted with saturated NaCl. ２ SO ３ After dilution with aqueous solution, the mixture was extracted with EtOAc. ２ SO ４ The mixture was dried with hexane, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (hexane / EtOAc = 6:1 to 4:1) to give product 9 as a colorless liquid. Entries 2 to 4 in Table 4 were also reacted under the conditions described in Table 4. Figure 11 shows the structure of product 9. １ The H NMR spectrum is shown. The reaction did not proceed in entry 3, where no catalyst was added, or in entry 4, where no blue LED was irradiated. In contrast, in entry 1, where PTHS-1 was used, it was confirmed that the organic photocatalyst and blue LED accelerated the reaction. On the other hand, in entry 2, where a commercially available phenothiazine catalyst (PTH-2) represented by the following formula was used, the reaction hardly proceeded. This is because the reduction potential of 1,3-bistrifluoromethylbenzene 7 is E p / 2 = -2.07 V vs SCE, and the PTH-2 catalyst (E 1 / 2 (C ・+ / C*) = -1.97 V vs SCE), one-electron reduction did not proceed efficiently and the reaction hardly proceeded. 1 / 2 (C ・+ This result shows the superiority of the PTHS catalyst, which has a stoichiometric ratio of 0.1 / C* = -2.34 V vs SCE. 1HNMR (600 MHz, CDCl3) δ 7.73 (s, 1H), 7.70 (d, J = 7.8 Hz, 1H), 7.66 (d, J = 7.8 Hz, 1H), 7.56 (t, J = 7.8 Hz, 1H), 3.65 (t, J = 6.3 Hz, 2H), 2.21-2.13 (m, 2H), 1.63-1.59 (m, 2H), 1.56-1.51 (m, 2H), 1.25 (s, 1H).

[0082]

[0083] Example 4 [Photoredox cross-coupling reaction of 4-trifluoromethylbenzene with triethylphosphite (Reference 9)]

[0084]

[0085]

[0086] In Entry 1 of Table 5, 4-iodotrifluoromethylbenzene 10 (14.5 μL, 0.1 mmol), triethyl phosphite (50 μL, 0.3 mmol), DBU (30 μL, 0.2 mmol), catalyst (10 mol%), and MeCN (1.0 mL) were added to a 4 mL vial. After argon bubbling for 5 minutes at 0°C, the resulting solution was stirred at room temperature under blue LED irradiation (λmax=425 nm) for 72 hours. The reaction mixture was added with H ２ The organic layer was extracted with EtOAc. ２ SO ４ The mixture was dried with hexane, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (hexane / EtOAc = 10:1 to 1:1) to obtain product 11 as a pale yellow liquid. Entries 2 to 5 in Table 5 were also reacted under the conditions described in Table 5. Figure 12 shows the structure of product 11. １ The H NMR spectrum is shown. The reaction did not proceed efficiently in entry 4, where no catalyst was added, or entry 5, where no blue LED was irradiated, confirming that the organic photocatalyst of the present invention and the blue LED accelerated this reaction. 1H NMR (600 MHz, CDCl3) δ 7.94 (dd, J = 12.6, 7.8 Hz, 2H), 7.73 (dd, J = 7.8, 3.6 Hz, 2H), 4.21-4.07 (m, 4H), 1.33 (t, J = 7.2 Hz, 6H).

[0087] Example 5 [Catalyst recycling reaction]

[0088]

[0089]

[0090] Photoredox cross-coupling reactions were carried out in the same manner as in Example 4 using PTHS-1 and commercially available PTH-1 represented by the following formula as catalysts. After the reaction was completed, the catalyst was recovered by extraction with EtOAc and column chromatography, and the recyclability of the catalyst was investigated. As shown in Table 6, PTHS-1 could be used repeatedly at least four times without losing catalytic activity. On the other hand, a decrease in yield was observed with the PTH-1 catalyst. These results confirmed that the PTHS photocatalyst of the present invention is more stable than conventional phenothiazine catalysts and can be used repeatedly in photocatalytic reactions. Therefore, it was found to be a recyclable organic photocatalyst.

[0091]

[0092] Example 6 [Photoredox cross-coupling reaction of 4-trifluoromethylbenzene with triethyl phosphite on a gram scale (Reference 9)]

[0093]

[0094] 4-Iodotrifluoromethylbenzene 10 (0.72 mL, 5.0 mmol), triethyl phosphite (2.57 mL, 15.0 mmol), DBU (1.49 mL, 10.0 mmol), PTHS-1 (236.9 mg, 10 mol%), and MeCN (50.0 mL) were added to a 200 mL three-neck flask. After argon bubbling at 0°C for 5 minutes, the resulting solution was stirred at room temperature under blue LED irradiation (λmax = 425 nm) for 72 hours. The reaction mixture was then added with H ２ The organic layer was extracted with EtOAc. ２ SO ４ The mixture was dried with hexane, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (hexane / EtOAc = 100:1 to 1:1) to obtain product 11 (1.194 g, 85% yield) as a pale yellow liquid. PTHS-1 (228.4 mg, 96% yield) was also recovered as a yellow solid. Thus, the reaction proceeded smoothly, successfully obtaining the target product in 85% yield. It was also found that the catalyst could be recovered in high yield (96%).

[0095] Comparative Example 1 [Photochemical sulfonylation of phenothiazine (Reference 10)]

[0096]

[0097] PTH-1 (55.1 mg, 0.2 mmol) and tosyl chloride (38.1 mg, 0.2 mmol) were added to a 4 mL vial. ２ After bubbling with 0.5% CO₂ for 5 minutes, MeCN (1.0 mL) was added. The resulting solution was irradiated with a blue LED (λ ｍａｘ = 425 nm) and stirred at room temperature for 24 hours. The mixture was concentrated under reduced pressure and purified by flash column chromatography (hexane / EtOAc = 100:1 to 4:1) to give product 12 (67.3 mg, 78% yield) as a yellow solid. Figure 13 shows the structure of product 12. １ The H NMR spectrum is shown. Thus, it was confirmed that the PTH-1 catalyst reacts with TsCl under light irradiation, resulting in tosylation of the p-position of the nitrogen atom. 1HNMR (600 MHz, CDCl3) δ 7.75 (d, J = 8.4 Hz, 2H), 7.62 (t, J = 7.8 Hz, 2H), 7.52 (t, J = 7.8 Hz, 1H), 7.47 (d, J = 1.8 Hz, 1H), 7.33-7.31 (m, 3H), 7.27-7.26 (m, 2H), 6.96-6.94 (m, 1H), 6.84-6.80 (m, 2H), 6.12-6.09 (m, 2H), 2.38 (s, 3H).

[0098] Example 7 [Photochemical sulfonylation of phenothiazine]

[0099]

[0100] PTHS-1 (94.7 mg, 0.2 mmol) and tosyl chloride (38.1 mg, 0.2 mmol) were added to a 4 mL vial. ２ After bubbling for 5 minutes, MeCN (1.0 mL) was added. The resulting solution was irradiated with a blue LED (λ ｍａｘ = 425 nm) and stirred at room temperature for 24 hours. The mixture was concentrated under reduced pressure and purified by flash column chromatography (hexane / EtOAc = 100:1), recovering PTHS-1 (89.5 mg, 95% yield) as a yellow solid. Thus, when a PTHS catalyst was used, recovery was successful with a 95% yield. That is, while the PTH-1 catalyst of Comparative Example 1 reacted and was deactivated under these reaction conditions, the PTHS photocatalyst of the present invention was recovered efficiently, demonstrating that it is a catalyst with excellent stability.

[0101] Example 8 [Photoredox cross-coupling reaction of chlorobenzene and triethyl phosphite]

[0102]

[0103] In the PTHS-1-catalyzed phosphorylation reaction, aryl chlorides substituted with cyano groups at the o-, m-, and p-positions were used. The reaction proceeded successfully, and the desired phosphate esters were successfully synthesized in moderate to high yields. Specifically, chlorobenzene 13 (0.2 mmol), triethyl phosphite 14 (71 μL, 0.6 mmol), DBU (60 μL, 0.4 mmol), catalyst (3 mol%), and MeCN (2.0 mL) were added to a 4 mL vial. After bubbling with Ar for 5 minutes, the resulting solution was stirred at room temperature under blue LED irradiation (λmax = 425 nm) for 24 hours. H2O was added to the reaction mixture, and the mixture was extracted with EtOAc. The organic layer was then washed with Na ２ SO ４ The residue was purified by preparative thin layer chromatography (EtOAc) to give product 15. 15a: 1 H NMR (600 MHz, CDCl3) δ 7.94-7.90 (m, 2H), 7.77-7.75 (m, 2H), 4.19-4.10 (m, 4H), 1.34 (t, J = 7.2 Hz, 6H). 15b: 1 H NMR (600 MHz, CDCl3) δ 8.10-8.02 (m, 2H), 7.82 (d, J = 7.8 Hz, 1H), 7.60 (m, 1H), 4.13 (m, 4H), 1.40 (t, J = 7.2 Hz, 6H). 15c: 1 H NMR (600 MHz, CDCl3) δ 8.12 (dd, J = 13.8, 7.2 Hz, 1H), 7.81 (m, 1H), 7.70-7.63 (m, 2H), 4.30-4.19 (m, 4H), 1.38 (t, J = 6.9 Hz, 6H).

[0104] References 1 to 11 are listed below. Reference 1: Chen, S.; Li, Z.; Hu, K.; Feng, W.; Mao, G.; Xiao, F.; Deng, G. Org. Biomol. Chem. 2023, 21, 1920-1926. Reference 2: Lamanna, G.; Faggi, C.; Gasparrini, F.; Ciogli, A.; Villani, C.; Stephens, PJ; Devlin, FJ; Menichetti, S. Chem. Eur. J. 2008, 14, 5747-5750. Reference 3: Liu, Y.; Xu, Y.; Zhang, Y.; Gao, W.; Shao, X. Org. Chem. Front. 2022, 9, 6490-6497. Reference 4: Yasu, Y.; Koike, T.; Akita, M. Angew. Chem. Int. Ed. 2012, 51, 9567-9571. Reference 5: Shibutani, S.; Kodo, T.; Takeda, M.; Nagao, K.; Tokunaga, N.; Sasaki, Y.; Ohmiya, HJ Am. Chem. Soc. 2020, 142, 1211-1216. Reference 6: Zheng, C.; Wang, Y.; Xu, Y.; Chen, Z.; Chen, G.; Liang, SH Org. Lett. 2018, 20, 4824-4827. Reference 7: Soulard, V.; Villa, G.; Vollmar, DP; Renaud, PJ Am. Chem. Soc. 2018, 140, 155-158. Reference 8: Wang, H.; Jui, NTJ Am. Chem. Soc. 2018, 140, 163-166. Reference 9: Pan, L.; Kelley, AS; Cooke, MV; Deckert, MM; Laulhe, S. ACS Sustainable Chem. Eng. 2022, 10, 691-695. Reference 10: Liu, J.; Liu, H.; Guo, X.; Wang, Z.; Wu, X.; Lee, J.; Zhu, C. Green Chem. 2023, 25, 3847-3851. Source: Neil, GC; William. EG Chem. Rev. Fr. 1996, 96, 877-910.

Claims

1. An organic photocatalyst comprising a compound represented by the following formula (1): [In formula (1), R １ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom (provided that R １ , R ６ and R ９ is a hydrogen atom), R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ may form a ring structure, X is a nitrogen atom or a boron atom, and Y and Z are each independently a sulfur atom, an oxygen atom, or —NR １２ - (R １２ is an alkyl group or an aryl group).

2. An organic photocatalyst comprising a compound represented by the following formula (2): [In formula (2), R １ ~R １１ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom (provided that R １ , R ６ and R ９ is a hydrogen atom), R １ and R ２ , R ２ and R ３ , R ３ and R ４ , R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ８ and R ９ , or R ９ and R １０ may form a ring structure.] 3. An organic photocatalyst comprising a compound represented by the following formula (2x): [In formula (2x), R １ , R ６ and R ９ are each independently an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a heteroaromatic ring group, or a halogen atom.

4. An organic photocatalyst comprising a compound represented by the following formula (2a), (2b) or (2c):

5. A method for producing an organic photocatalyst containing a compound represented by formula (2) according to claim 2, comprising reacting a cyclohexanone derivative represented by the following formula (3) with ammonium halide and elemental sulfur: [In formula (3), R １ ~R １１ has the same meaning as the formula (2).

6. A method for producing an organic photocatalyst containing a compound represented by formula (2) according to claim 2, comprising reacting a triphenylamine derivative represented by the following formula (4) with phthalimidosulfenyl halide to obtain a thiophthalamide compound, and then reacting the thiophthalamide compound with aluminum halide. [In formula (4), R １ ~R １１ has the same meaning as the formula (2).

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