Method for preparing arenobufagin arginine carbamate compound by one-pot method

Abstract

The invention discloses a method for preparing arenobufagin arginine carbamate compounds by a one-pot method, which comprises the following steps: # imgabs0. According to the method for preparing arenobufagin arginine carbamate compounds by the one-pot method provided by the invention, the used raw materials and reagents are conventional chemical raw materials which are low in cost and easy to obtain, few in three wastes, high in yield and high in purity.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for preparing toufovin carbamate compounds by a one-pot process. Background Art

[0002] Toad venom is a natural product with broad-spectrum anti-tumor activity, with multiple effects such as anti-angiogenesis and tumor cell apoptosis. However, it has disadvantages such as narrow therapeutic window, cardiotoxicity, and poor water solubility. Patent application with publication number CN113368051A discloses a toad venom-loaded nanomicelle with good water solubility; patent application with publication number CN112062804A discloses structural modification of toad venom at positions 3 and 11 to improve anti-tumor activity, but the yields of various modified products obtained are less than 80%; patent application with publication number CN111763236A and patent application with publication number CN110483608A disclose structural modification of toad venom at position 3 to produce toad venom carbamate derivatives to obtain derivatives with good anti-tumor activity, but the overall yield is not high, most of which are less than 70%;

[0003] At present, the route for synthesizing bufotoxin-3-carbamate derivatives is as follows (patent application with publication number CN110483608A):

[0004]

[0005] Scheme 1: Synthesis of bufotoxin carbamate

[0006] The above-mentioned synthetic route cannot avoid the formation of bufotoxin-3,11-biscarbamate derivatives. The specific route is as follows (patent application with publication number CN111763236A):

[0007]

[0008] Scheme 2: Synthesis of bufotoxin biscarbamate

[0009] The above methods for synthesizing bufotoxin-3-carbamate have the disadvantages of low total yield and many by-products. Summary of the invention

[0010] The purpose of the present invention is to provide a one-pot method for preparing bufotoxin carbamate compounds.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] In a first aspect of the present invention, a one-pot method for preparing bufotoxin carbamate compounds is provided, comprising the following steps:

[0013]

[0014] R is selected from one of the following structures:

[0015]

[0016] At a temperature of 0 to 30° C. (preferably 0 or 25° C.), a molar ratio of 1:1 to 5 (preferably 1:1) of bufotoxin, i.e., compound 1, is mixed with triphosgene, and a dry solvent is added. Under argon protection, a base 1 is slowly added dropwise, wherein the molar ratio of bufotoxin to the base 1 is 1:2-15 (preferably 1:3). The mixture is stirred for reaction for 1 to 5 hours (preferably 2 hours), and the mixture is naturally cooled to room temperature. A nitrogen-containing substrate is added, wherein the molar ratio of bufotoxin to the nitrogen-containing substrate is 1:1-10 (preferably 1:2), and then a base 2 is added dropwise, wherein the molar ratio of bufotoxin to the base 2 is 1:2-15 (preferably 1:3). The mixture is stirred at room temperature overnight to obtain the bufotoxin carbamate compound.

[0017] The solvent is selected from dichloromethane.

[0018] The base 1 is selected from at least one of triethylamine, DMAP, diisopropylethylamine, pyridine, potassium carbonate, sodium carbonate, sodium hydroxide and sodium bicarbonate.

[0019] The base 2 is selected from at least one of triethylamine, DMAP, diisopropylethylamine, pyridine, potassium carbonate, sodium carbonate, sodium hydroxide and sodium bicarbonate.

[0020] The nitrogen-containing substrate is selected from 3,3-difluoropyrrole and 4,4-difluoropiperidine.

[0021] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0022] The one-pot method for preparing bufotoxin carbamate compounds provided by the present invention uses conventional chemical raw materials and reagents, which are cheap and easy to obtain, have less three wastes, high yield and high purity. The present invention uses triphosgene to react with bufotoxin to generate bufotoxin-3-chloroformate without separation, and then reacts with 3,3-difluoropyrrolidine to generate bufotoxin-3-(3,3-difluoropyrrolidinyl)carbamate, and reacts with 4,4-difluoropiperidine to generate bufotoxin-3-(4,4-difluoropiperidinyl)carbamate, avoiding the problem of overreaction, having a higher yield, reducing the post-processing steps, and having a simple and efficient synthesis route.

[0023] The preparation method of the invention is simple, practical and easy to industrialize.

[0024] The present invention does not generate 3-position, 11-di(difluoroamino)carboxylic acid ester impurities of bufotoxin in the preparation process, reduces the difficulty of product purification, improves product quality and yield, and the total yield of two steps is also above 88%. The technical problems of low yield and difficult purification in the preparation process are well solved. The synthesis method of the present invention is simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the hydrogen spectrum of the preparation of toad venom carbamate compounds in Example 1 of the present invention.

[0026] Figure 2 This is a schematic diagram of the LC-MS spectrum of the preparation of toad venom carbamate compounds in Example 1 of the present invention.

[0027] Figure 3 This is a schematic diagram of the hydrogen spectrum of the preparation of toad venom carbamate compounds in Example 5 of the present invention.

[0028] Figure 4 This is a schematic diagram of the LC-MS spectrum of the preparation of toad venom carbamate compounds in Example 5 of the present invention. DETAILED DESCRIPTION

[0029] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0030] Example 1

[0031] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0032]

[0033] In an ice-water bath, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, and triethylamine (60 mmol, 6.1 g) was slowly added dropwise under argon protection. The mixture was stirred for 2 hours, and the temperature was naturally lowered to room temperature. 3,3-difluoropyrrole (40 mmol, 4.3 g) was added, and triethylamine (60 mmol, 6.1 g) was added dropwise. The mixture was stirred at room temperature overnight to react, and the solvent was concentrated to remove the solvent. The mixture was purified by column chromatography (dichloromethane: methanol = 100: 1, Rf = 0.2) to obtain 10.1 g of compound 4 as an off-white solid with a yield of 92% and a purity of 98.7%. The test data are shown in FIG. Figure 1 and Figure 2 As shown, Figure 1This is a schematic diagram of the hydrogen spectrum of the preparation of toad venom carbamate compounds in Example 1 of the present invention. Figure 2 This is a schematic diagram of the LC-MS spectrum of the preparation of toad venom carbamate compounds in Example 1 of the present invention. 1 H NMR(400MHz,Chloroform-d)δ7.73(d,1H),7.39(s,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.84(s,1H),3 .76(t,1H),3.65(t,1H),2.09–2.48(m,3H),2.04–2.07(m,3H),1.70–1.95(m,9H),1.26–1.38(m,4H),1.19(s,3H),0.96(s,3H); MS: [MH] + 550.65.

[0034] Example 2

[0035] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0036]

[0037] At room temperature, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, and triethylamine (60 mmol, 6.1 g) was slowly added dropwise under argon protection, and stirred for 2 hours. 3,3-difluoropyrrole (40 mmol, 4.3 g) was added, and triethylamine (60 mmol, 6.1 g) was then added dropwise. The mixture was stirred at room temperature overnight to react, and the solvent was concentrated to remove the solvent. The mixture was purified by column chromatography (dichloromethane: methanol = 100: 1, Rf = 0.2) to obtain 9.7 g of compound 4, with a yield of 88% and a purity of 98.3%. 1 H NMR(400MHz,Chloroform-d)δ7.73(d,1H),7.39(s,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.84(s,1H),3 .76(t,1H),3.65(t,1H),2.09–2.48(m,3H),2.04–2.07(m,3H),1.70–1.95(m,9H),1.26–1.38(m,4H),1.19(s,3H),0.96(s,3H); MS: [MH] + 550.65.

[0038] Example 3

[0039] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0040]

[0041] At room temperature, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, pyridine (60 mmol, 4.8 g) was slowly added dropwise under argon protection, and the mixture was stirred for 2 hours. 3,3-difluoropyrrole (40 mmol, 4.3 g) was added, and pyridine (60 mmol, 4.8 g) was then added dropwise. The mixture was stirred at room temperature overnight to react, the solvent was removed by concentration, and the mixture was purified by column chromatography (dichloromethane: methanol = 100: 1, Rf = 0.2) to obtain 8.9 g of compound 4 as an off-white solid with a yield of 81% and a purity of 98.3%. 1 H NMR(400MHz,Chloroform-d)δ7.73(d,1H),7.39(s,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.84(s,1H),3 .76(t,1H),3.65(t,1H),2.09–2.48(m,3H),2.04–2.07(m,3H),1.70–1.95(m,9H),1.26–1.38(m,4H),1.19(s,3H),0.96(s,3H); MS: [MH] + 550.65.

[0042] Example 4

[0043] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0044]

[0045] At room temperature, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, and diisopropylethylamine (60 mmol, 7.8 g) was slowly added dropwise under argon protection, and stirred for 2 hours. 3,3-difluoropyrrole (40 mmol, 4.3 g) was added, and diisopropylethylamine (60 mmol, 7.8 g) was then added dropwise. The mixture was stirred at room temperature overnight to react, and the solvent was concentrated to remove the solvent. The mixture was purified by column chromatography (dichloromethane: methanol = 100: 1, Rf = 0.2) to obtain 8.5 g of compound 4 as an off-white solid with a yield of 77% and a purity of 97.1%.1 H NMR(400MHz,Chloroform-d)δ7.73(d,1H),7.39(s,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.84(s,1H),3 .76(t,1H),3.65(t,1H),2.09–2.48(m,3H),2.04–2.07(m,3H),1.70–1.95(m,9H),1.26–1.38(m,4H),1.19(s,3H),0.96(s,3H); MS: [MH] + 550.65.

[0046] Example 5

[0047] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0048]

[0049] Under an ice-water bath, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, and triethylamine (60 mmol, 6.1 g) was slowly added dropwise under argon protection. The mixture was stirred for 2 hours, and then naturally cooled to room temperature. 4,4-difluoropiperidine (40 mmol, 4.9 g) was added, and triethylamine (60 mmol, 6.1 g) was added dropwise. The mixture was stirred at room temperature overnight to react, and the solvent was removed by concentration. The mixture was purified by column chromatography (dichloromethane: methanol = 100: 1, Rf = 0.2) to obtain 10.6 g of compound 5 as an off-white solid with a yield of 94% and a purity of 100.0%. Figure 3 This is a schematic diagram of the hydrogen spectrum of the preparation of toad venom carbamate compounds in Example 5 of the present invention. Figure 4 This is a schematic diagram of the LC-MS spectrum of the preparation of toad venom carbamate compounds in Example 5 of the present invention. 1 H NMR(400MHz,Chloroform-d)δ7.72(d,1H),7.39(d,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.83 (d,1H),3.61(s,4H),2.48(d,1H),1.92–2.07(m,7H),1.67–1.86(m,9H),1.26–1.40(m,4H),1.20(s,3H),0.92(s,3H); MS: [MH] + 564.65.

[0050] Example 6

[0051] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0052]

[0053] At room temperature, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, and triethylamine (60 mmol, 6.1 g) was slowly added dropwise under argon protection, and the mixture was stirred for 2 hours. 4,4-difluoropiperidine (40 mmol, 4.9 g) was added, and triethylamine (60 mmol, 6.1 g) was then added dropwise. The mixture was stirred at room temperature overnight to react, the solvent was removed by concentration, and the mixture was purified by column chromatography (dichloromethane: methanol = 100: 1, Rf = 0.2) to obtain 10.1 g of compound 5 as an off-white solid with a yield of 89% and a purity of 99.1%. 1 H NMR(400MHz,Chloroform-d)δ7.72(d,1H),7.39(d,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.83 (d,1H),3.61(s,4H),2.48(d,1H),1.92–2.07(m,7H),1.67–1.86(m,9H),1.26–1.40(m,4H),1.20(s,3H),0.92(s,3H); MS: [MH] + 564.65.

[0054] Example 7

[0055] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0056]

[0057] At room temperature, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, and pyridine (60 mmol, 4.8 g) was slowly added dropwise under argon protection. The mixture was stirred for 2 hours, and then 4,4-difluoropiperidine (40 mmol, 4.9 g) was added, and then pyridine (60 mmol, 4.8 g) was added dropwise. The mixture was stirred at room temperature overnight to react, and the solvent was concentrated to remove the solvent. The mixture was purified by column chromatography (dichloromethane: methanol = 100: 1, Rf = 0.2) to obtain 9.7 g of compound 5 as an off-white solid with a yield of 86% and a purity of 98.9%. 1H NMR(400MHz,Chloroform-d)δ7.72(d,1H),7.39(d,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.83 (d,1H),3.61(s,4H),2.48(d,1H),1.92–2.07(m,7H),1.67–1.86(m,9H),1.26–1.40(m,4H),1.20(s,3H),0.92(s,3H); MS: [MH] + 564.65.

[0058] Example 8

[0059] A one-pot method for preparing bufotoxin carbamate compounds comprises the following steps:

[0060]

[0061] At room temperature, bufotoxin, i.e., compound 1 (20 mmol, 8.3 g) and triphosgene (20 mmol, 6.0 g) were placed in a 250 ml three-necked flask, 100 ml of dry dichloromethane was added, and diisopropylethylamine (60 mmol, 7.8 g) was slowly added dropwise under argon protection, and stirred for 2 hours, then 4,4-difluoropiperidine (40 mmol, 4.9 g) was added, and diisopropylethylamine (60 mmol, 7.8 g) was added dropwise, and stirred at room temperature overnight to react, the solvent was concentrated to remove, and column purification (dichloromethane: methanol = 100: 1, Rf = 0.2) was performed to obtain 9.3 g of compound 5 as an off-white solid, with a yield of 82% and a purity of 98.4%; 1 H NMR(400MHz,Chloroform-d)δ7.72(d,1H),7.39(d,1H),6.29(d,1H),5.01(s,1H),4.31-4.34(m,1H),4.09-4.13(m,1H),3.83 (d,1H),3.61(s,4H),2.48(d,1H),1.92–2.07(m,7H),1.67–1.86(m,9H),1.26–1.40(m,4H),1.20(s,3H),0.92(s,3H); MS: [MH] + 564.65.

[0062] The synthesis method of the invention not only avoids the problem of overreaction, but also has a high yield and high purity, and the synthesis method is simple, efficient, green and environmentally friendly.

[0063] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A method for preparing bufotoxin carbamate compounds by a one-pot process, characterized in that: The following steps are involved: R is selected from one of the following structures: At a temperature of 0 to 30° C., a molar ratio of 1:1 to 5 of bufotoxin, i.e., compound 1, is mixed with triphosgene, and a dry solvent is added. Under argon protection, a base 1 is slowly added dropwise, wherein the molar ratio of bufotoxin to the base 1 is 1:2-15. The mixture is stirred for reaction for 1 to 5 hours, and the mixture is naturally cooled to room temperature. A nitrogen-containing substrate is added, wherein the molar ratio of bufotoxin to the nitrogen-containing substrate is 1:1-10. Then, a base 2 is added dropwise, wherein the molar ratio of bufotoxin to the base 2 is 1:2-15. The mixture is stirred at room temperature overnight to obtain the bufotoxin carbamate compound.

2. The one-pot method for preparing bufotoxin carbamate compounds according to claim 1, characterized in that: The solvent is selected from dichloromethane.

3. The one-pot method for preparing bufotoxin carbamate compounds according to claim 1, characterized in that: The base 1 is selected from at least one of triethylamine, DMAP, diisopropylethylamine, pyridine, potassium carbonate, sodium carbonate, sodium hydroxide and sodium bicarbonate.

4. The one-pot method for preparing bufotoxin carbamate compounds according to claim 1, characterized in that: The base 2 is selected from at least one of triethylamine, DMAP, diisopropylethylamine, pyridine, potassium carbonate, sodium carbonate, sodium hydroxide and sodium bicarbonate.

5. The one-pot method for preparing bufotoxin carbamate compounds according to claim 1, characterized in that: The nitrogen-containing substrate is selected from 3,3-difluoropyrrole and 4,4-difluoropiperidine.

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