Click reaction element aocn derivative or salt thereof

Abstract

To provide a novel cyclic alkyne compound.SOLUTION: The present disclosure relates to a compound represented by formula (I) or a salt thereof. [In formula (I), n is an integer of 1 to 10, and X is an amino group or a hydroxy group.]SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a click reaction element AOCN derivative or a salt thereof. [Background technology]

[0002] The click reaction is widely used in pharmaceutical development research, functional material development research, biochemistry research, etc., because it can link molecules simply and quickly. A typical click reaction is a cycloaddition reaction that proceeds between a compound having an azide group and a compound having a terminal alkyne group. Research has been conducted on cyclic alkynes such as 4,8-diazacyclononyne as reaction substrates that can undergo cycloaddition reactions without using a copper catalyst (for example, Patent Documents 1 and 2 and Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-39773 [Patent Document 2] Patent No. 7320821 [Non-patent literature]

[0004] [Non-Patent Document 1] Runyan Ni, etal., “Heteroatom-embedded Medium-Sized Cycloalkynes: Concise Synthesis, Structural Analysis, and Reactions”, Angewandte Chemie International Edition, 2015,54, p.1190-1194 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a novel cyclic alkyne compound and a method for producing the same. [Means for solving the problem]

[0006] The present invention relates to the following inventions. [1] A compound represented by the following formula (I) or a salt thereof: [ka] [In formula (I), n represents an integer of 1 to 10, and X represents an amino group or a hydroxy group.] [2] The compound or salt thereof according to [1], wherein n is 1. [3] The compound or salt thereof according to [1] or [2], wherein X is -NH2. [4] A compound represented by the following formula (IIa): [ka] [In formula (II), n represents an integer of 1 to 10.] [5] The compound according to [4], wherein n is 1. [6] The following formula (I): [ka] [In formula (I), n represents an integer of 1 to 10, and X represents an amino group or a hydroxy group.] or a salt thereof, The following formula (II): [ka] [In formula (II), n represents an integer of 1 to 10, and Y represents an amino group protected by a protecting group or a hydroxy group protected by a protecting group.] The method includes a deprotection step of deprotecting a protecting group in a compound represented by the formula: [7] The Y is an amino group protected by a phthaloyl group, The method according to [6], wherein the deprotection step is a step of reacting the compound represented by formula (II) with 1,3-propanediamine to deprotect the phthaloyl group. [8] The following formula (II): [ka] [In formula (II), n represents an integer of 1 to 10, and Y represents an amino group protected by a protecting group or a hydroxy group protected by a protecting group.] A method for producing a compound represented by the formula: a step of reacting 1,4-butynediol with dicobalt octacarbonyl to obtain a reactant (a-1); and a step of reacting the reactant (a-1) with a compound represented by the formula (1): [ka] [In formula (1), n ​​and Y have the same meanings as n and Y in formula (II)] with a compound represented by the formula (a-2) to obtain a reactant (a-2); A method comprising the step of reacting reactant (a-2) with ammonium cerium (IV) nitrate to obtain the compound represented by formula (II). [Effects of the Invention]

[0007] According to the present invention, a novel cyclic alkyne compound and a method for producing the same can be provided. The compound of the present invention has high solubility in water and organic solvents, high click reactivity, and is capable of linking to multiple molecules. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described. However, the following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to the following contents.

[0009] <Compound or its salt> The compound of this embodiment is a compound represented by the following formula (I) (hereinafter also referred to as "compound (I)"). Compound (I) is a compound having a 4-aza-8-oxacyclononyne (AOCN) skeleton, and can be linked to a molecule containing an azide group via a triple bond, and can be linked to a molecule containing a functional group reactive with X via X, and is therefore also referred to as a multi-linked AOCN. [ka]

[0010] In formula (I), n represents an integer of 1 to 10. The lower limit of n may be 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. n is preferably 1 because it is easy to synthesize and has a low molecular weight. X represents an amino group (-NH2) or a hydroxy group (-OH).

[0011] Compound (I) is preferably a compound (Ia) represented by the following formula (Ia) in which n is 1 and X is an amino group. [ka]

[0012] Salts of Compound (I) include salts of Compound (I) with inorganic or organic acids. Examples of inorganic acids include hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, and phosphoric acid. Examples of organic acids include organic carboxylic acids and organic sulfonic acids. Examples of organic carboxylic acids include acetic acid, fumaric acid, maleic acid, succinic acid, citric acid, tartaric acid, adipic acid, lactic acid, and trifluoroacetic acid. Examples of organic sulfonic acids include methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid.

[0013] Because compound (I) contains a nine-membered cyclic alkyne structure, it can undergo a cycloaddition reaction with an azide compound without using a catalyst such as a copper catalyst. Compound (I) has a 4-aza-8-oxacyclononyne skeleton, and therefore has higher click reactivity than nine-membered cyclic alkyne compounds having a 4,8-diazacyclononyne skeleton.

[0014] Compound (I) is a compound having a 4-aza-8-oxacyclononyne skeleton, and therefore has superior solubility in water and organic solvents compared to nine-membered cyclic alkyne compounds having a 4,8-diazacyclononyne (DACN) skeleton and cyclic alkyne compounds containing two benzene rings, such as dibenzocyclooctyne (DBCO). Furthermore, compound (I) has improved thermal and chemical stability compared to dibenzocyclooctyne (DBCO), and is less susceptible to nonspecific adsorption to proteins and the like.

[0015] Compound (I) and its salts have a reactive functional group X introduced into the 4-aza-8-oxacyclononyne skeleton, and can be linked to other molecules via X. The other molecules are not particularly limited, and various functional molecules can be used. Examples of functional molecules include fluorescent dyes.

[0016] The method for linking Compound (I) and its salts with other molecules is not particularly limited, and methods utilizing, for example, amidation, ureation, and thioureation can be used. Examples of other molecules include N-hydroxysuccinimide (NHS) esters, carboxylic acids (HO-C(=O)-R), acid chlorides (Cl-C(=O)-R), acid anhydrides (RC(=O)-OC(=O)-R), isocyanates (O=C=NR), isothiocyanates (S=C=NR), and sulfonyl chlorides (Cl-S(O)-R). Condensing agents, etc., can be used for linking as needed.

[0017] Compound (I) and its salts can be molecularly linked, for example, by reaction with an NHS ester, a reaction in combination with a carboxylic acid and a condensing agent, or an acid chloride to form an amidated product, by reaction with an isocyanate to form a ureated product, by reaction with a thioisocyanate to form a thioureated product, or by reaction with a sulfonamidated product, thereby enabling the introduction of various fluorescent molecules, radioisotopes, biotin, physiologically active molecules, etc. A specific example of molecular linkage using compound (Ia) is shown in the following formula. The starting material used in the molecular linkage shown in the following formula is not limited to compound (Ia), and for example, a salt of compound (Ia) can also be used.

[0018] [ka]

[0019] <Method for producing compound (I)> Compound (I) is, for example, a compound represented by the following formula (II): [ka] [In formula (II), n has the same meaning as n in formula (I), and Y represents an amino group protected by a protecting group or a hydroxy group protected by a protecting group.] The compound can be produced by a method including a deprotection step of removing a protecting group in an intermediate compound represented by the following formula:

[0020] Examples of protecting groups for amino groups include phthaloyl (Phth), tert-butoxycarbonyl (Boc), 9-fluorenylmethyloxycarbonyl (Fmoc), and 2-nitrobenzenesulfonyl (Ns) groups. Examples of protecting groups for hydroxy groups include methoxymethyl ether (MOM), tetrahydropyranyl (THP), trityl (Tr), tert-butyl (t-Bu), trialkylsilyl groups (e.g., TMS, TES, TIPS, TBS, and TBDPS groups), and acetyl groups.

[0021] The conditions for deprotecting the protecting group in the intermediate compound can be appropriately set depending on the type of protecting group, etc. The intermediate compound is preferably a compound represented by the following formula (IIa) (hereinafter referred to as "compound (IIa)") in which Y is an amino group protected by a Phth group. [ka]

[0022] When the intermediate compound is compound (IIa), the deprotection step is preferably a step of reacting compound (IIa) with 1,3-propanediamine to obtain compound (I). When 1,3-propanediamine is used, the deprotection of the Phth group can suppress side reaction products (e.g., compounds in which alkynes are reduced) compared to when hydrazine, which is commonly used, is used.

[0023] In the deprotection step, the amount (number of moles) of 1,3-propanediamine used is preferably 2.0 or more relative to the number of moles of the intermediate compound, and although there is no particular upper limit, it is, for example, 10.0 or less, or 5.0 or less.

[0024] The reaction temperature in the deprotection step is not particularly limited, but is, for example, 40° C. or higher, or 45° C. or higher, and 60° C. or lower, or 55° C. or lower. The time for which the reaction is maintained at the reaction temperature (reaction time) is not particularly limited, but is, for example, 1 hour or higher, 5 hours or higher, or 10 hours or higher, and 30 hours or lower, or 20 hours or lower.

[0025] The deprotection step is preferably carried out in the presence of an organic solvent, such as ethanol, tetrahydrofuran, or a combination thereof, and may be carried out with stirring.

[0026] After the reaction, it is preferable to carry out post-treatment as necessary, such as filtration, washing with an organic solvent and removal of the solvent, and purification using a silica gel column.

[0027] <Method for producing intermediate compounds> The intermediate compound can be prepared, for example, by reacting 2-butyne-1,4-diol with dicobalt octacarbonyl (Co2(CO)8) to obtain reactant (a-1), and by reacting reactant (a-1) with boron trifluoride diethyl ether complex (BF3·OEt2) in the presence of the compound represented by formula (1): [ka] [In formula (1), n ​​and Y have the same meanings as n and Y in formula (II)] and a step (a-3) of reacting the reactant (a-2) with ammonium cerium (IV) nitrate to obtain an intermediate compound.

[0028] In step (a-1), 2-butyne-1,4-diol is reacted with Co2(CO)8. The reactant (a-1) obtained in step (a-1) contains a cobalt complex formed by the reaction of 2-butyne-1,4-diol with Co2(CO)8.

[0029] In step (a-1), the ratio of the number of moles of Co2(CO)8 to the number of moles of 1,4-butynediol is, for example, 0.8 or more, or 0.9 or more, or 1.2 or less, or 1.1 or less.

[0030] Step (a-1) is preferably carried out in the presence of an organic solvent, such as dichloromethane, and can be carried out with stirring.

[0031] The reaction temperature in step (a-1) is not particularly limited, but is, for example, 20 to 40° C. or 25 to 35° C. The time for which the reaction temperature is maintained (reaction time) is not particularly limited, but is, for example, 10 minutes or more, 20 minutes or more, or 30 minutes or more, and 60 minutes or less.

[0032] In step (a-2), reactant (a-1) is reacted with compound (1) in the presence of BF3·OEt2 to obtain reactant (a-2) containing a nine-membered cyclic alkyne cobalt complex.

[0033] In step (a-2), the amount (number of moles) of compound (1) used relative to the number of moles of 1,4-butynediol or the number of moles of Co2(CO)8 is not particularly limited, but is, for example, 0.8 or more, or 0.9 or more, and 1.2 or less, or 1.1 or less.

[0034] In step (a-2), the amount (number of moles) of BF3·OEt2 used relative to the number of moles of 1,4-butynediol or the number of moles of Co2(CO)8 is, for example, preferably 1.0 or more, 1.5 or more, 2.0 or more, or 2.3 or more, and preferably less than 3.0, 2.8 or less, or 2.6 or less. When the amount (number of moles) of BF3·OEt2 used is within the above-mentioned numerical range, the generation of by-products is likely to be suppressed.

[0035] Step (a-2) can be carried out after step (a-1) without performing operations such as separating and purifying the target compound in the reaction product (a-1).

[0036] In step (a-3), reactant (a-2) is reacted with ammonium cerium (IV) nitrate to remove cobalt from the 9-membered cyclic alkyne cobalt complex in reactant (a-2).

[0037] Step (a-3) is preferably carried out in the presence of silica gel, and can be carried out after step (a-2) without performing operations such as separating and purifying the target compound in the reaction product (a-2).

[0038] The amount (molar number) of ammonium cerium (IV) nitrate used relative to the number of moles of 1,4-butynediol or the number of moles of Co2(CO)8 is not particularly limited, but is, for example, 2.0 or more, 2.5 or more, or 3.0 or more, and 10.0 or less, or 5.0 or less.

[0039] The intermediate compound is preferably treated with ammonium cerium (IV) nitrate and then subjected to post-treatment. The intermediate compound can be obtained, for example, by mixing and stirring aminopropylated silica gel and pyridine after treatment with ammonium cerium (IV) nitrate, then washing the solid obtained by filtration, and then purifying it using a silica gel column. [Example]

[0040] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. In the following examples, the nuclear magnetic resonance spectrum (NMR) of the obtained compound was measured by placing the compound dissolved in a heavy solvent in a sample tube with an outer diameter of 5 mm at room temperature using a spectrometer (manufactured by JEOL, product name: ECX500).

[0041] <Synthesis of Multi-linked AOCN> [Synthesis of intermediate compounds] [ka]

[0042] CHCl (50 mL) and 237 mg (2.76 mmol) of 1,4-butynediol were added to a 500 mL three-neck flask, which had been heated and dried under vacuum. 944 mg (2.76 mmol) of Co(CO) was added to the reaction mixture. The reaction mixture was stirred at 30°C for 30 minutes, after which CHCl (170 mL) was added to the three-neck flask. After stirring for 10 minutes, 862 mg (2.76 mmol) of compound 1a and 866 μL (6.90 mmol) of BF·OEt were added and stirred for 20 minutes. 23 g of silica gel and 4.54 g (8.28 mmol) of cerium ammonium nitrate were added to the reaction mixture and stirred for 1 hour and 30 minutes. 23 g of aminopropylated silica gel and 556 μL (6.90 mmol) of pyridine were added to the reaction mixture and stirred for 1 hour. The mixture was then filtered under vacuum through a filter paper. The solid on the filter paper was washed five times with a mixed solvent of chloroform and methanol (mixing ratio 10:1), and the solvent was evaporated under reduced pressure. The resulting crude product was purified on a silica gel column (silica gel 50 g, developing solvent chloroform / THF / ethyl acetate = 10:1:1) to obtain 452 mg (45%) of an intermediate compound represented by formula (IIa) where n is 1 (hereinafter also referred to as "Compound IIa").

[0043] [NMR data of intermediate compounds] 1 H NMR(500MHz,CDCl3):δ 7.88-7.84(m,2H),7.76-7.71(m,2H),4.16(t,J=7.5Hz,2H),4.12(t,J=2.5Hz,2H),4.03(t,J=2.5Hz, 2H),3.88(t,J=5.0Hz,2H),3.55(t,J=5.0Hz,2H),3.36(t,J=7.5Hz,2H),1.91(tt,J=5.0,5.0Hz,2H). 13 C NMR (125MHz, CDCl3): δ 167.5,134.2,131.7,123.5,92.6,89.0,65.0,59.3,47.9,44.4,40.9,32.9,32.2.

[0044] [Synthesis of Multi-linked AOCN] [ka]

[0045] A 30 mL recovery flask was charged with 100 mg (0.276 mmol) of the intermediate, 5 mL of ethanol, and 5 mL of THF, and then 45.9 μL (0.552 mmol) of 1,3-propanediamine was added. After stirring at 50°C for 3 hours, 22.9 μL (0.276 mmol) of 1,3-propanediamine was added and the mixture was stirred at 50°C for an additional 16 hours. The solid was removed by filtration, washed with chloroform, and the solvent was evaporated under reduced pressure. The crude product was purified on a silica gel column (15 g of silica gel, chloroform / methanol = 8:1) to yield 60 mg (94%) of poly-linked AOCN.

[0046] [NMR data of multi-linked AOCN] 1 H NMR(500MHz,CDCl3):δ 4.11(t,J=2.5Hz,2H),3.97(t,J=2.5Hz,2H),3.87(t,J=5.0Hz,2H),3.49(t,J=5.0 Hz,2H),3.20(t,J=6.0Hz,2H),3.06(t,J=6.0Hz,2H),1.88(tt,J=5.0,5.0Hz,2H). 13 C NMR (125MHz, CDCl3): δ 92.4,89.1,65.0,59.3,53.1,44.3,40.8,36.6,33.1.

[0047] [Preparation of Poly-Linked AOCN Hydrochloride] 134 mg (0.578 mmol) of poly-linked AOCN and 6.5 mL of acetonitrile were added to a 50 mL recovery flask, and 50.0 μL (0.635 mmol) of 37% aqueous hydrochloric acid solution was added. After stirring at room temperature for 5 minutes, the mixture was filtered, and the resulting solid was washed with ethyl acetate and dried in vacuo to obtain 99.5 mg (64%) of the hydrochloride salt of poly-linked AOCN.

[0048] [NMR data of multi-linked AOCN hydrochloride] 1H NMR(500MHz,CD3OD):δ 4.18(t,J=2.5Hz,2H),4.11(t,J=2.5Hz,2H),3.92(t,J=5.5Hz,2H),3.59(t,J=5.5Hz,2H),3.50-3.43(m,4H),δ1.93(tt,J=5.5,5.5Hz,2H). 13 C NMR(125MHz,CD3OD):δ 93.4,90.1,66.1,59.9,47.8,45.8,41.6,35.4,34.4.

[0049] <Molecular linkage at the amine moiety of multi-linked AOCN> Multi-linked AOCN reacts with acid anhydrides to give amides, which allows molecular linkage. Below is an example of the reaction with acetic anhydride. [ka]

[0050] The multi-linked AOCN reacts with thioisocyanate to give thiourea, which allows molecular linkage. Below is an example of the reaction with fluorescein isothioisocyanate. [ka]

[0051] The hydrochloride salt of poly-linked AOCN reacts with sulfonyl chloride in the presence of a base to give sulfonamide, which allows molecular linkage. An example of the reaction with dansyl chloride is shown below. [ka]

[0052] <Reactivity evaluation of multi-linked AOCN> The click reaction between benzyl azide and the intermediate compound (compound IIa) of the multi-linked AOCN was carried out, and the reaction rate constant was determined. The reaction was carried out in acetonitrile-d3 at a concentration of 5 mM, and the reaction mixture was kept in a constant temperature bath at 25°C. 1The product was quantified at regular intervals by H NMR analysis (internal standard: 1,3,5-trimethoxybenzene). From the quantitative values, the second-order reaction rate constant of AOCN was calculated to be k = 1.6 × 10 -2 M -1 s -1 The second-order reaction rate constant of DACN was calculated as k = 3.0 × 10 -3 M -1 s -1 It was revealed that the reaction rate of AOCN was about five times faster than that of DACN.

[0053] <Solubility evaluation of multi-linked AOCN> The solubilities of N-Ms-DACN acetamide and AOCN acetamide in water and methanol were determined. The solubility of N-Ms-DACN acetamide in water was <0.2 mg / mL and that of methanol was <0.3 mg / mL, whereas the solubility of AOCN acetamide in water was 3.61 mg / mL and that of methanol was 14.3 mg / mL. [ka]

[0054] <Stability evaluation of multi-linked AOCN> A solution was prepared by adding compound IIa (60.0 mg), 1,3,5-trimethoxybenzene (internal standard, 27.0 mg), and 10 mL of toluene to a 20 mL screw-cap test tube, and a portion of the solution was concentrated to obtain 1 H NMR analysis was performed. After replacing the gas inside the test tube with argon, it was sealed and heated at 80°C for 12 days. After heating, a portion of the solution was concentrated. 1 H NMR analysis was performed. 1 H NMR analysis showed no significant change in the area ratio of compound IIa to the internal standard, suggesting that heating at 80°C for 12 days did not significantly decompose compound IIa.

Claims

1. A compound represented by the following formula (I) or a salt thereof: 【Chemical 1】 [In formula (I), n represents an integer of 1 to 10, and X represents an amino group or a hydroxy group.]

2. 2. The compound or salt thereof according to claim 1, wherein n is 1.

3. X is -NH ２ 3. The compound or salt thereof according to claim 1 or 2, wherein:

4. A compound represented by the following formula (IIa): 【Chemistry 2】 [In formula (II), n represents an integer of 1 to 10.]

5. 5. The compound of claim 4, wherein n is 1.

6. The following formula (I): 【Chemistry 3】 [In formula (I), n represents an integer of 1 to 10, and X represents an amino group or a hydroxy group.] or a salt thereof, The following formula (II): 【Chemistry 4】 [In formula (II), n represents an integer of 1 to 10, and Y represents an amino group protected by a protecting group or a hydroxy group protected by a protecting group.] The method includes a deprotection step of deprotecting a protecting group in a compound represented by the formula:

7. Y is an amino group protected by a phthaloyl group, The method according to claim 6, wherein the deprotection step is a step of reacting the compound represented by formula (II) with 1,3-propanediamine to deprotect the phthaloyl group.

8. The following formula (II): 【Chemistry 5】 [In formula (II), n represents an integer of 1 to 10, and Y represents an amino group protected by a protecting group or a hydroxy group protected by a protecting group.] A method for producing a compound represented by the formula: a step of reacting 1,4-butynediol with dicobalt octacarbonyl to obtain a reaction product (a-1); In the presence of a boron fluoride diethyl ether complex, reactant (a-1) and a compound of formula (1): 【Chemistry 6】 [In formula (1), n ​​and Y have the same meanings as n and Y in formula (II)] with a compound represented by the formula (a-2) to obtain a reactant (a-2); A method comprising the step of reacting reactant (a-2) with ammonium cerium (IV) nitrate to obtain the compound represented by formula (II).

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