Click reaction element aocn derivative or salt thereof

Abstract

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.]

Description

Click reaction element AOCN derivative or salt thereof

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

[0002] The click reaction is widely used in pharmaceutical research, functional materials research, biochemistry research, and other fields 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).

[0003] JP 2018-39773 A Japanese Patent No. 7320821

[0004] Runyan Ni, etal., “Heteroatom-embedded Medium-Sized Cycloalkynes: Concise Synthesis, Structural Analysis, and Reactions”, Angewandte Chemie International Edition, 2015,54, p.1190-1194

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

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

[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.

[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 Salt Thereof> 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 via a triple bond to a molecule containing an azide group, and can also be linked via X to a molecule containing a functional group reactive with X, and is therefore also referred to as a multi-molecule-linked AOCN.

[0010] In formula (I), n represents an integer of 1 to 10. The upper 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 (-NH ２ ), or a hydroxy group (—OH).

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

[0012] Salts of compound (I) include salts of compound (I) with inorganic acids 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 9-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 salts thereof 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 for example, methods utilizing amidation reaction, ureation reaction, and thioureation reaction can be used. Examples of other molecules include N-hydroxysuccinimide (NHS) ester, carboxylic acid (HO-C(=O)-R), acid chloride (Cl-C(=O)-R), acid anhydride (R-C(=O)-O-C(=O)-R), isocyanate (O=C=N-R), isothiocyanate (S=C=N-R), sulfonyl chloride (Cl-S(O)-R), and the like. A condensing agent or the like can be used for linking, if necessary.

[0017] Compound (I) and its salts can be molecularly linked, for example, by reaction with an NHS ester, or a reaction in combination with a carboxylic acid and a condensing agent, or by reaction with an acid chloride to form an amidated product, or by reaction with an isocyanate to form a ureated product, or by reaction with a thioisocyanate to form a thioureated product, or by reaction with a sulfonamidated product, thereby allowing 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 for 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]

[0019] <Method of Producing Compound (I)> Compound (I) can be produced by, for example, a method for producing a compound represented by the following formula (II): [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.]

[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), 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 "compound (IIa)") in which Y is an amino group protected by a Phth group.

[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. The amount (number of moles) of 1,3-propanediamine used is not particularly limited relative to the number of moles of the intermediate compound, and is, for example, 2.0 or more and 10.0 or less, or 2.0 or more and 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 reaction temperature in the deprotection step is not particularly limited, but is, for example, 40°C or higher and 60°C or lower, 40°C or higher and 55°C or lower, 45°C or higher and 60°C or lower, or 45°C or higher and 55°C or lower. The time for which the reaction temperature is maintained (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. The time for which the reaction temperature is maintained (reaction time) is not particularly limited, but is, for example, 1 hour or higher and 30 hours or lower, 1 hour or higher and 20 hours or lower, 5 hours or higher and 30 hours or lower, 5 hours or higher and 20 hours or lower, 10 hours or higher and 30 hours or lower, or 10 hours or higher and 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 compound> The intermediate compound can be produced by, for example, a method for producing a 2-butyne-1,4-diol compound by a reaction of 2-butyne-1,4-diol with octacarbonyl dicobalt (Co ２ (CO) ８ ) and a step (a-1) of reacting the compound (a-1) with boron trifluoride diethyl ether complex (BF ３ ・OEt ２ ) in the presence of reactant (a-1) and a compound of formula (1): [In formula (1), n ​​and Y are defined as n and Y in formula (II)] to obtain a reactant (a-2), and a step (a-3) to obtain an intermediate compound by reacting the reactant (a-2) with ammonium cerium (IV) nitrate.

[0028] In step (a-1), 2-butyne-1,4-diol and Co ２ (CO) ８ The reaction product (a-1) obtained by the step (a-1) is a mixture of 2-butyne-1,4-diol and Co. ２ (CO) ８ This includes cobalt complexes formed by reaction with

[0029] In step (a-1), the ratio of Co to the moles of 1,4-butynediol ２ (CO) ８ Examples of the ratio of the number of moles of Co to the number of moles of 1,4-butynediol are 0.8 or more, or 0.9 or more, or 1.2 or less, or 1.1 or less. ２ (CO) ８ Examples of the ratio of the number of moles of 1 to 1.2 are 0.8 or more and 1.2 or less, 0.8 or more and 1.1 or less, 0.9 or more and 1.2 or less, or 0.9 or more and 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. The time for which the reaction temperature is maintained (reaction time) is not particularly limited, but is, for example, 10 minutes or more and 60 minutes or less, 20 minutes or more and 60 minutes or less, or 30 minutes or more and 60 minutes or less.

[0032] In step (a-2), BF ３ ・OEt ２ The reactant (a-1) is reacted with the compound (1) in the presence of the following: In step (a-2), a reactant (a-2) containing a 9-membered cyclic alkyne cobalt complex is obtained.

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

[0034] In step (a-2), BF ３ ・OEt ２ The amount (moles) of 1,4-butynediol or Co ２ (CO) ８ For example, the molar ratio is preferably 1.0 or more, 1.5 or more, 2.0 or more, or 2.3 or more, and is preferably less than 3.0, 2.8 or less, or 2.6 or less, relative to the number of moles of BF. ３ ・OEt ２ The amount (moles) of 1,4-butynediol or Co ２ (CO) ８For example, it is preferable that the molar ratio of BF is 1.0 or more and less than 3.0, 1.0 or more and less than 2.8, 1.0 or more and less than 2.6, 1.5 or more and less than 3.0, 1.5 or more and less than 2.8, 1.5 or more and less than 2.6, 2.0 or more and less than 3.0, 2.0 or more and less than 2.8, 2.0 or more and less than 2.6, 2.3 or more and less than 3.0, 2.3 or more and less than 2.8, or 2.3 or more and less than 2.6. ３ ・OEt ２ When the amount (number of moles) used is within the above-mentioned 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), the reactant (a-2) is reacted with ammonium cerium (IV) nitrate to remove cobalt from the 9-membered cyclic alkyne cobalt complex in the 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 is determined based on the mole number of 1,4-butynediol or Co ２ (CO) ８ The amount (molar number) of ammonium cerium (IV) nitrate used 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, relative to the number of moles of 1,4-butynediol or Co. ２ (CO) ８ The number of moles of is not particularly limited, but is, for example, 2.0 to 10.0, 2.0 to 5.0, 2.5 to 10.0, 2.5 to 5.0, or 3.0 to 10.0, or 3.0 to 5.0.

[0039] The intermediate compound is preferably treated with ammonium cerium (IV) nitrate and then subjected to post-treatment, and 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.

[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 Compound]

[0042] A 500 mL three-neck flask was heated and dried under vacuum. ２ Cl ２ (50 mL), 237 mg (2.76 mmol) of 1,4-butynediol were added, and Co ２ (CO) ８ The reaction mixture was stirred at 30°C for 30 minutes, and then CH ２ Cl ２ The reaction mixture was stirred for 10 minutes, and then 862 mg (2.76 mmol) of compound 1a and BF ３ ・OEt ２866 μL (6.90 mmol) of the above was 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 solution 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 solution and stirred for 1 hour, followed by vacuum filtration through 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 using a silica gel column (50 g of silica gel, 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, CDCl ３ ):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 (125 MHz, CDCl ３ ): 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 Multimolecularly Linked AOCN]

[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 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 using a silica gel column (15 g of silica gel, chloroform / methanol = 8:1) to yield 60 mg (94%) of multi-linked AOCN.

[0046] [NMR data of multi-linked AOCN] １ H NMR (500MHz, CDCl ３ ):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 (125 MHz, CDCl ３ ): 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. The resulting solid was washed with ethyl acetate and dried in vacuo to yield 99.5 mg (64%) of the hydrochloride salt of poly-linked AOCN.

[0048] [NMR data of poly-linked AOCN hydrochloride] １ H NMR (500MHz, CD ３OD): 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, CD ３ OD): 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. An example of the reaction with acetic anhydride is shown below.

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

[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.

[0052] <Reactivity Evaluation of Poly-Linked AOCN> A click reaction with benzyl azide was carried out using an intermediate compound (compound IIa) of poly-linked AOCN, and the reaction rate constant was determined. The reaction was carried out in deuterated acetonitrile at a concentration of 5 mM, and the reaction mixture was left to stand in a thermostatic bath at 25°C. １ The 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 as 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 AOCN reacts about five times faster than DACN.

[0053] <Evaluation of Solubility of Poly-Linked AOCN> The solubility in water and methanol of N-Ms-DACN acetamide and AOCN acetamide was determined. The results showed that the solubility of N-Ms-DACN acetamide in water was <0.2 mg / mL and the solubility in methanol was <0.3 mg / mL, while the solubility of AOCN acetamide in water was 3.61 mg / mL and the solubility in methanol was 14.3 mg / mL.

[0054] <Evaluation of Stability of Multimolecularly Linked AOCN> Compound IIa (60.0 mg), 1,3,5-trimethoxybenzene (internal standard, 27.0 mg), and 10 mL of toluene were added to a 20 mL screw-cap test tube to prepare a solution, and a portion of the solution was concentrated to obtain a solution of 10 mL of toluene. １ H NMR analysis was performed. After the inside of the test tube was replaced with argon, it was sealed and heated at 80°C for 12 days. After heating, a part of the solution was concentrated. １ H NMR analysis was performed. １ As a result of H NMR analysis, no significant change was observed in the area ratio of compound IIa to the internal standard, which indicates that heating at 80°C for 12 days does not significantly decompose compound IIa.

Claims

1. A compound represented by the following formula (I) or a salt thereof: [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 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): [In formula (II), n represents an integer of 1 to 10.] 5. The compound of claim 4, wherein n is 1.

6. The following formula (I): [wherein n represents an integer of 1 to 10, and X represents an amino group or a hydroxy group] or a salt thereof, the method comprising: [wherein 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.] 7. The method according to claim 6, wherein Y is an amino group protected by a phthaloyl group, and 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): [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 following formula (1): [wherein n and Y have the same meanings as n and Y in formula (II)] to obtain a reactant (a-2), and a reactant (a-2) with ammonium cerium (IV) nitrate to obtain the compound represented by formula (II).

Images