Preparation method of tryptophan derivative medical intermediate
1. A preparation method of a tryptophan derivative medical intermediate is disclosed, wherein the structural formula of the tryptophan derivative medical intermediate is shown as a formula (I), and the preparation method is characterized by comprising any one of the following two schemes:
the first scheme is as follows: taking an L-tryptophan derivative shown as a formula (II) as an initial raw material, and sequentially carrying out esterification, amidation, Boc protection, hydrolysis and amidation to obtain a target product, namely a tryptophan derivative medical intermediate shown as a formula (I), wherein the reaction equation is as follows:
wherein R is methyl or methoxy, and R is C4, C5 or C6 substituted;
scheme II: taking an L-tryptophan derivative shown as a formula (II) as a starting material, sequentially carrying out esterification, amidation, Boc protection, hydrogenation, hydrolysis and amidation to obtain a compound shown as a formula (I), wherein the first step of esterification and the last step of amidation are the same as those in the first scheme, and the reaction equation is as follows:
wherein R is methyl or methoxy, and R is C4, C5 or C6.
2. The method for preparing the pharmaceutical intermediate of tryptophan derivative according to claim 1, wherein the first embodiment comprises the following steps:
(1) taking an L-tryptophan derivative shown in a formula (II) and methanol as initial raw materials, heating to reflux in the presence of a catalyst A for esterification reaction, after the reaction is finished, cooling, concentrating to remove the methanol, adding a saturated sodium bicarbonate solution for alkalizing until the pH value is 8-9, adding an extracting agent A for extraction, taking an organic phase, washing with water, drying, filtering and concentrating sequentially to obtain an intermediate compound shown in a formula (III);
(2) adding a compound shown as a formula (III) into tetrahydrofuran, carrying out amidation reaction with trifluoroacetic anhydride TFAA under the action of alkali A, concentrating to remove tetrahydrofuran after the reaction is finished, washing with water, filtering, and drying to obtain a compound shown as a formula (IV);
(3) adding a compound shown as a formula (IV) into a solvent A, carrying out amidation reaction with Boc anhydride under the action of a catalyst B, adding water and an extracting agent B after the reaction is finished, washing an organic phase with water, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (V);
(4) adding a compound shown as a formula (V) into a mixed solvent B, carrying out hydrolysis reaction under the action of alkali B, concentrating to remove part of solvent after the reaction is finished, adding an extracting agent C, adjusting the pH value of a water layer to 5-7 at low temperature, extracting by using the extracting agent, washing an organic phase by using saturated saline solution, drying, filtering and concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (VI);
(5) sequentially adding a compound shown as a formula (VI), an aqueous solution of alkali C and 9-fluorenylmethyl-N-succinimidyl carbonate into a solvent C, carrying out amidation reaction at room temperature, concentrating to remove the solvent C after the reaction is finished, adding an extracting agent D, washing an organic phase with a saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a target compound, namely the N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan derivative shown as the formula (I).
3. The method for preparing the pharmaceutical intermediate of the tryptophan derivative according to claim 2, wherein the catalyst A in the step (1) is concentrated sulfuric acid, phosphoric acid, thionyl chloride or hydrogen chloride, preferably concentrated sulfuric acid or thionyl chloride, and the mass ratio of the catalyst A to the L-tryptophan derivative represented by the formula (II) is 1.0-4.0: 1, preferably 1.5-3.0: 1; the extractant A is dichloromethane, ethyl acetate, chloroform or toluene, preferably dichloromethane or chloroform.
4. The method for preparing a tryptophan derivative medical intermediate according to claim 2, wherein the mass ratio of trifluoroacetic anhydride to the compound represented by the formula (III) in the step (2) is 0.8-3.0: 1, preferably 1.0-2.5: 1; the base A is pyridine, triethylamine or N, N-diisopropylethylamine, and the mass ratio of the base A to the compound shown in the formula (III) is 1.0-2.0: 1, preferably 1.0-1.8: 1.
5. The method for preparing the tryptophan derivative medical intermediate as claimed in claim 2, wherein the catalyst B in the step (3) is 4-dimethylaminopyridine or 4-pyrrolidinylpyridine, preferably 4-dimethylaminopyridine, and the mass ratio of the catalyst B to the compound represented by the formula (IV) is 0.04-0.20: 1, preferably 0.06-0.18: 1; the solvent A is dichloromethane, tetrahydrofuran, dioxane, acetone or acetonitrile, preferably tetrahydrofuran or acetonitrile; the mass ratio of Boc anhydride to the compound represented by the formula (IV) is 1.0-1.5: 1, preferably 1.1-1.3: 1; the extractant B is dichloromethane, petroleum ether, chloroform, 1, 2-dichloroethane, ethyl acetate or methyl acetate, preferably dichloromethane and ethyl acetate.
6. The method for preparing the tryptophan derivative medical intermediate as claimed in claim 2, wherein the base B in the step (4) is sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide or lithium hydroxide, preferably potassium carbonate or sodium hydroxide, and the mass ratio of the base B to the compound represented by the formula (V) is 2.0-4.0: 1, preferably 2.0-3.0: 1; the mixed solvent B is methanol/water, tetrahydrofuran/water, acetonitrile/water, ethanol/water, isopropanol/water, preferably methanol/water; the extractant C is dichloromethane, chloroform, diethyl ether, ethyl acetate or methyl acetate, preferably dichloromethane and ethyl acetate; the alkali C in the step (5) is sodium carbonate or sodium bicarbonate, and the mass ratio of the alkali C to the compound shown in the formula (VI) is 1.0-3.0: 1, preferably 1.5-2.5: 1; the solvent C is 1, 4-dioxane, tetrahydrofuran, acetonitrile and ethyl acetate, preferably ethyl acetate and tetrahydrofuran; the mass ratio of the 9-fluorenylmethyl-N-succinimidyl carbonate to the compound represented by the formula (VI) is 1.0-1.5: 1, preferably 1.0-1.2: 1; the extractant D is dichloromethane, chloroform, diethyl ether, ethyl acetate or methyl acetate, and preferably ethyl acetate.
7. The method for preparing the pharmaceutical intermediate of tryptophan derivative according to claim 1, wherein the second embodiment comprises the following steps:
(1) taking an L-tryptophan derivative shown in a formula (II) and methanol as initial raw materials, heating to reflux in the presence of a catalyst A for esterification reaction, after the reaction is finished, cooling, concentrating to remove the methanol, adding a saturated sodium bicarbonate solution for alkalizing until the pH value is 8-9, adding an extracting agent A for extraction, taking an organic phase, washing with water, drying, filtering and concentrating sequentially to obtain an intermediate compound shown in a formula (III);
(2) sequentially adding a compound shown in a formula (III), an aqueous solution of alkali C and N-benzyl succinimide carbonate into a solvent C, carrying out amidation reaction at room temperature, concentrating to remove the solvent C after the reaction is finished, adding an extracting agent D, washing an organic phase with a saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown in a formula (VII);
(3) adding a compound shown as a formula (VII) into a solvent A, carrying out amidation reaction with Boc anhydride under the action of a catalyst B, adding water and an extracting agent B after the reaction is finished, washing an organic phase with water, drying, filtering and concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (VIII);
(4) adding a compound represented by the formula (VIII) into a solvent D to obtain a hydrogen donor H2Carrying out catalytic hydrogenation reaction under the action of a catalyst C, after the reaction is finished, filtering the catalyst C, washing the catalyst C by a solvent D to remove the catalyst C, concentrating an organic phase, and recrystallizing and purifying a concentrated product to obtain a compound shown in a formula (IX);
(5) adding a compound shown as a formula (IX) into a mixed solvent B, carrying out hydrolysis reaction under the action of alkali B, concentrating to remove part of solvent after the reaction is finished, adding an extracting agent C, adjusting the pH value of a water layer to 5-7 at low temperature, extracting by using the extracting agent, washing an organic phase by using saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (VI), namely an N-in-tert-butoxycarbonyl-L-tryptophan derivative;
(6) sequentially adding a compound shown as a formula (VI), an aqueous solution of alkali C and 9-fluorenylmethyl-N-succinimidyl carbonate into a solvent C, carrying out amidation reaction at room temperature, concentrating to remove the solvent C after the reaction is finished, adding an extracting agent D, washing an organic phase with a saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a target compound, namely the N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan derivative shown as the formula (I).
8. The method for preparing a tryptophan derivative pharmaceutical intermediate according to claim 7, wherein the mass ratio of the N-benzylsuccinimide carbonate to the compound represented by the formula (III) in the step (2) is 1.0 to 1.5:1, preferably 1.0 to 1.2: 1; the alkali is sodium carbonate, and the mass ratio of the sodium carbonate to the compound shown in the formula (III) is 1.0-2.0: 1, preferably 1.5-2.0: 1.
9. The process according to claim 7, wherein the hydrogen donor H in step (4) is selected from the group consisting of2Hydrogen balloon is adopted to participate in the reaction; the catalyst C is 5-10% of palladium-carbon, 10-20% of palladium hydroxide-carbon or palladium-polyethyleneimine, and preferably 5-10% of palladium-carbon; the solvent D is methanol, ethanol, ethyl acetate and tetrahydrofuran, preferably methanol and ethyl acetate.
10. The process according to claim 7, wherein the base in step (5) is potassium carbonate, and the ratio of the base to the compound of formula (IX) is 1.0-2.0: 1, preferably 1.0-1.5: 1.
Background
Amino acids are the most basic substances constituting proteins required for the nutrition of organisms, have remarkable physiological properties in the body, and are one of the indispensable nutritional components of the organisms; the amino acid has wide application, such as food, medicine, feed, etc.
The polypeptide medicine has the advantages of high activity, stable curative effect, small toxic and side effect, small dosage, specific action target and the like, is widely involved in the fields of anti-tumor, cardiovascular and cerebrovascular, antiviral and antibacterial active peptides, vaccines, diagnostic kits and the like, and has wide application prospect. However, the natural polypeptide drugs have the defects of low content, low purity and the like, and thus cannot meet the requirements of clinical application. At present, the introduction of an unnatural amino acid structural unit is a very effective method to overcome the inherent defects of natural polypeptide drugs, which is of great significance for the popularization of the application of the polypeptide drugs.
The chemical synthesis of polypeptide is to connect different amino acids in a certain order through peptide bonds, and in order to avoid side reactions, amino groups and other active groups (indole, imidazole and the like) which do not participate in the reaction need to be protected in advance to obtain the polypeptide with a specific order.
The N-alpha-fluorenylmethyloxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan derivative is a common intermediate for synthesizing various polypeptides and various medicaments, such as a hypoglycemic medicament, namely the somaglutide, the teriparatide for treating osteoporosis and the like, and the structural formula of the somaglutide is as follows:
at present, no report is made on the preparation method of the N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan derivative. The key of the preparation method of the N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan derivative is the preparation of the N-in-tert-butyloxycarbonyl-L-tryptophan derivative, namely alpha-NH2Protection and deprotection.
Disclosure of Invention
The invention aims to provide a method for preparing a tryptophan derivative medical intermediate N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan derivative by using an L-tryptophan derivative as a raw material. The method has the characteristics of simple process, convenient operation, mild conditions, higher yield, higher purity, lower cost and the like.
The preparation method of the tryptophan derivative medical intermediate is characterized by comprising any one of the following two schemes:
the first scheme is as follows: taking an L-tryptophan derivative shown as a formula (II) as an initial raw material, and sequentially carrying out esterification, amidation, Boc protection, hydrolysis and amidation to obtain a target product, namely a tryptophan derivative medical intermediate shown as a formula (I), wherein the reaction equation is as follows:
in the formula, R is hydrogen or methyl or methoxy substituted at C4, 5 and 6 positions;
scheme II: taking an L-tryptophan derivative shown as a formula (II) as a starting material, sequentially carrying out esterification, amidation, Boc protection, hydrogenation, hydrolysis and amidation to obtain a compound shown as a formula (I), wherein the first step of esterification and the last step of amidation are the same as those in the first scheme, and the reaction equation is as follows:
wherein R is hydrogen or methyl or methoxy substituted at C4, 5 and 6 positions.
The preparation method of the tryptophan derivative medical intermediate is characterized in that the first scheme specifically comprises the following steps:
(1) taking an L-tryptophan derivative shown in a formula (II) and methanol as initial raw materials, heating to reflux in the presence of a catalyst A for esterification reaction, after the reaction is finished, cooling, concentrating to remove the methanol, adding a saturated sodium bicarbonate solution for alkalizing until the pH value is 8-9, adding an extracting agent A for extraction, taking an organic phase, washing with water, drying, filtering and concentrating sequentially to obtain an intermediate compound shown in a formula (III);
(2) adding a compound shown as a formula (III) into tetrahydrofuran, carrying out amidation reaction with trifluoroacetic anhydride TFAA under the action of alkali A, concentrating to remove tetrahydrofuran after the reaction is finished, washing with water, filtering, and drying to obtain a compound shown as a formula (IV);
(3) adding a compound shown as a formula (IV) into a solvent A, carrying out amidation reaction with Boc anhydride under the action of a catalyst B, adding water and an extracting agent B after the reaction is finished, washing an organic phase with water, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (V);
(4) adding a compound shown as a formula (V) into a mixed solvent B, carrying out hydrolysis reaction under the action of alkali B, concentrating to remove part of solvent after the reaction is finished, adding an extracting agent C, adjusting the pH value of a water layer to 5-7 at low temperature, extracting by using the extracting agent, washing an organic phase by using saturated saline solution, drying, filtering and concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (VI);
(5) sequentially adding a compound shown as a formula (VI), an aqueous solution of alkali C and 9-fluorenylmethyl-N-succinimidyl carbonate into a solvent C, carrying out amidation reaction at room temperature, concentrating to remove the solvent C after the reaction is finished, adding an extracting agent D, washing an organic phase with a saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a target compound, namely the N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan derivative shown as the formula (I).
The preparation method of the tryptophan derivative medical intermediate is characterized in that R is H and 5-Me.
The preparation method of the tryptophan derivative medical intermediate is characterized in that a catalyst A in the step (1) in the scheme one is concentrated sulfuric acid, phosphoric acid, thionyl chloride and hydrogen chloride, preferably concentrated sulfuric acid and thionyl chloride, and the mass ratio of the catalyst to the L-tryptophan derivative shown in the formula (II) is 1.0-4.0: 1, preferably 1.5-3.0: 1; the extractant A is dichloromethane, ethyl acetate, chloroform, toluene, etc., preferably dichloromethane and chloroform.
The preparation method of the tryptophan derivative medical intermediate is characterized in that the mass ratio of trifluoroacetic anhydride to the compound shown in the formula (III) in the step (2) in the scheme one is 0.8-3.0: 1, preferably 1.0-2.5: 1; the base A is pyridine, triethylamine and N, N-diisopropylethylamine, and the mass ratio of the base A to the compound shown in the formula (III) is 1.0-2.0: 1, preferably 1.0-1.8: 1.
The preparation method of the tryptophan derivative medical intermediate is characterized in that a catalyst B in the step (3) in the scheme one is 4-dimethylaminopyridine or 4-pyrrolidinylpyridine, preferably 4-dimethylaminopyridine, and the mass ratio of the catalyst B to a compound shown in a formula (IV) is 0.04-0.20: 1, preferably 0.06-0.18: 1; the solvent A is dichloromethane, tetrahydrofuran, dioxane, acetone and acetonitrile, preferably tetrahydrofuran and acetonitrile; the mass ratio of Boc anhydride to the compound represented by the formula (IV) is 1.0-1.5: 1, preferably 1.1-1.3: 1; the extractant B is dichloromethane, petroleum ether, chloroform, 1, 2-dichloroethane, ethyl acetate or methyl acetate, preferably dichloromethane and ethyl acetate;
the preparation method of the tryptophan derivative medical intermediate is characterized in that the alkali B in the step (4) in the first scheme is sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide and lithium hydroxide, preferably potassium carbonate and sodium hydroxide, and the mass ratio of the alkali B to the compound shown in the formula (V) is 2.0-4.0: 1, preferably 2.0-3.0: 1; the mixed solvent B is methanol/water, tetrahydrofuran/water, acetonitrile/water, ethanol/water, isopropanol/water, preferably methanol/water; the extractant C is dichloromethane, chloroform, diethyl ether, ethyl acetate or methyl acetate, preferably dichloromethane and ethyl acetate;
the preparation method of the tryptophan derivative medical intermediate is characterized in that the alkali C in the step (5) in the scheme one is sodium carbonate or sodium bicarbonate, and the mass ratio of the alkali C to the compound shown in the formula (VI) is 1.0-3.0: 1, preferably 1.5-2.5: 1; the solvent C is 1, 4-dioxane, tetrahydrofuran, acetonitrile and ethyl acetate, preferably ethyl acetate and tetrahydrofuran; the mass ratio of the 9-fluorenylmethyl-N-succinimidyl carbonate to the compound represented by the formula (VI) is 1.0-1.5: 1, preferably 1.0-1.2: 1; the extractant D is dichloromethane, chloroform, diethyl ether, ethyl acetate or methyl acetate, and preferably ethyl acetate.
The preparation method of the tryptophan derivative medical intermediate is characterized in that the second scheme specifically comprises the following steps:
(1) taking an L-tryptophan derivative shown in a formula (II) and methanol as initial raw materials, heating to reflux in the presence of a catalyst A for esterification reaction, after the reaction is finished, cooling, concentrating to remove the methanol, adding a saturated sodium bicarbonate solution for alkalizing until the pH value is 8-9, adding an extracting agent A for extraction, taking an organic phase, washing with water, drying, filtering and concentrating sequentially to obtain an intermediate compound shown in a formula (III);
(2) sequentially adding a compound shown in a formula (III), an aqueous solution of alkali C and N-benzyl succinimide carbonate into a solvent C, carrying out amidation reaction at room temperature, concentrating to remove the solvent C after the reaction is finished, adding an extracting agent D, washing an organic phase with a saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown in a formula (VII);
(3) adding a compound shown as a formula (VII) into a solvent A, carrying out amidation reaction with Boc anhydride under the action of a catalyst B, adding water and an extracting agent B after the reaction is finished, washing an organic phase with water, drying, filtering and concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (VIII);
(4) adding a compound represented by the formula (VIII) into a solvent D to obtain a hydrogen donor H2Carrying out catalytic hydrogenation reaction under the action of a catalyst C, after the reaction is finished, filtering the catalyst C, washing the catalyst C by a solvent D to remove the catalyst C, concentrating an organic phase, and recrystallizing and purifying a concentrated product to obtain a compound shown in a formula (IX);
(5) adding a compound shown as a formula (IX) into a mixed solvent B, carrying out hydrolysis reaction under the action of alkali B, concentrating to remove part of solvent after the reaction is finished, adding an extracting agent C, adjusting the pH value of a water layer to 5-7 at low temperature, extracting by using the extracting agent, washing an organic phase by using saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a compound shown as a formula (VI), namely an N-in-tert-butoxycarbonyl-L-tryptophan derivative;
(6) sequentially adding a compound shown as a formula (VI), an aqueous solution of alkali C and 9-fluorenylmethyl-N-succinimidyl carbonate into a solvent C, carrying out amidation reaction at room temperature, concentrating to remove the solvent C after the reaction is finished, adding an extracting agent D, washing an organic phase with a saturated saline solution, drying, filtering, concentrating, and recrystallizing and purifying a concentrated product to obtain a target compound, namely the N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan derivative shown as the formula (I).
The preparation method of the tryptophan derivative medical intermediate is characterized in that the mass ratio of the N-benzyl succinimide carbonate to the compound shown in the formula (III) in the step (2) in the scheme II is 1.0-1.5: 1, preferably 1.0-1.2: 1; the alkali is sodium carbonate, and the mass ratio of the sodium carbonate to the compound shown in the formula (III) is 1.0-2.0: 1, preferably 1.5-2.0: 1;
the preparation method of the tryptophan derivative medical intermediate is characterized in that the catalyst C in the step (4) in the scheme II is a hydrogen donor H2Hydrogen balloon is adopted to participate in the reaction; 5-10% palladium-carbon, 10-20% palladium hydroxide-carbon or palladium-polyethyleneimine, preferably 5-10% palladium-carbon; the solvent D is methanol, ethanol, ethyl acetate and tetrahydrofuran, preferably methanol and ethyl acetate.
The preparation method of the tryptophan derivative medical intermediate is characterized in that the base in the step (5) in the second scheme is potassium carbonate, and the mass ratio of the potassium carbonate to the compound shown in the formula (IX) is 1.0-2.0: 1, preferably 1.0-1.5: 1.
By adopting the technology, compared with the prior art, the invention has the following beneficial effects:
(1) the raw materials used in the invention are cheap and easily available, and the used reagent is environment-friendly;
(2) the preparation process is simple, the reaction condition is mild, and the post-treatment has good operability;
(3) the product prepared by the preparation method has high yield and purity, and is easy for industrial production.
Detailed Description
The technical solutions of the present invention are described below by way of specific examples, but the scope of the present invention is not limited thereto. The raw materials and reagents used are all commercial products.
Example 1
The first synthetic scheme for preparing the tryptophan derivative medical intermediate (I) in the invention is as follows:
(I) preparation of L-Tryptophan methyl ester (III-a)
Adding L-tryptophan (4.085g, 20mmol) and 40mL of methanol into a 100mL three-neck flask with a magnetic stirring thermometer, slowly dropwise adding thionyl chloride (4.758g, 40mmol) under an ice bath at-10 ℃, ensuring the temperature of the reaction liquid to be below room temperature, heating to reflux after the dropwise adding for esterification reaction, and monitoring the reaction end by TLC. Cooling, concentrating to remove methanol, adding saturated sodium bicarbonate solution to basify until the pH value is 8-9, adding dichloromethane to extract (3 × 20ml), taking an organic layer to wash with water (2 × 15ml), drying with anhydrous sodium sulfate, and concentrating to obtain 4.348g of yellow oily L-tryptophan methyl ester (III-a), wherein the yield is 99.6% and the HPLC purity of the product is 98.56%.
Preparation of (di) L-Tryptophan methyl ester (III-a)
Adding L-tryptophan (4.085g, 20mmol) and 40mL of methanol into a 100mL three-neck flask with a magnetic stirring thermometer, slowly dropwise adding concentrated sulfuric acid (4.511g, 46mmol) in an ice bath at-10 ℃, ensuring the temperature of the reaction liquid to be below room temperature, heating to reflux after the dropwise adding for esterification, and monitoring the reaction by TLC to finish. Cooling, concentrating to remove methanol, adding saturated sodium bicarbonate solution to alkalize until the pH value is 8-9, adding chloroform for extraction (3 × 20ml), taking an organic layer for washing (2 × 15ml), drying by anhydrous sodium sulfate, and concentrating to obtain 3.985g of white solid L-tryptophan methyl ester (III-a), wherein the yield is 91.3%, and the HPLC purity of the product is 98.70%.
Preparation of (tri) L-Tryptophan methyl ester (III-a)
Adding L-tryptophan (4.085g, 20mmol) and 40mL of methanol into a 100mL three-neck flask with a magnetic stirring thermometer, slowly dropwise adding concentrated sulfuric acid (5.296g, 54mmol) in an ice bath at-10 ℃, ensuring the temperature of the reaction liquid to be below room temperature, heating to reflux after the dropwise adding for esterification, and monitoring the reaction by TLC to finish. Cooling, concentrating to remove methanol, adding saturated sodium bicarbonate solution to alkalize until the pH value is 8-9, adding dichloromethane to extract (3 × 20ml), taking an organic layer to wash with water (2 × 15ml), drying by using anhydrous sodium sulfate, and concentrating to obtain 4.243g of white solid L-tryptophan methyl ester (III-a), wherein the yield is 97.2%, and the HPLC purity of the product is 98.94%.
Preparation of (tetra) 5-methyl-L-tryptophan methyl ester (III-b)
5-methyl-L-tryptophan (4.365g, 20mmol) and 40mL of methanol are added into a 100mL three-neck flask with a magnetic stirring thermometer, thionyl chloride (5.948g, 50mmol) is slowly added dropwise under an ice bath at the temperature of minus 10 ℃, the temperature of a reaction solution is ensured to be below room temperature, after the addition is finished, the temperature is raised to reflux for esterification reaction, and the reaction is monitored by TLC to be finished. Cooling, concentrating to remove methanol, adding saturated sodium bicarbonate solution to alkalize until the pH value is 8-9, adding dichloromethane to extract (3 × 20ml), taking an organic layer to wash with water (2 × 15ml), drying by anhydrous sodium sulfate, and concentrating to obtain 4.571g of yellow oily 5-methyl-L-tryptophan methyl ester (III-b), wherein the yield is 98.4% and the product HPLC purity is 98.61%.
(penta) preparation of 5-methyl-L-Tryptophan methyl ester (III-b)
Adding 5-methyl-L-tryptophan (4.365g and 20mmol) and 40mL of methanol into a 100mL three-neck flask with a magnetic stirring thermometer, slowly dropwise adding concentrated sulfuric acid (5.884g and 60mmol) at-10 ℃ in an ice bath, ensuring the temperature of the reaction liquid to be below room temperature, heating to reflux after the dropwise adding is finished to perform esterification reaction, and monitoring the reaction by TLC. Cooling, concentrating to remove methanol, adding saturated sodium bicarbonate solution to alkalize until the pH value is 8-9, adding chloroform for extraction (3 × 20ml), taking an organic layer for washing (2 × 15ml), drying by anhydrous sodium sulfate, and concentrating to obtain 4.506g of white solid 5-methyl-L-tryptophan methyl ester (III-b), wherein the yield is 97.0%, and the HPLC purity of the product is 98.32%.
(Hexa) preparation of 5-methyl-L-Tryptophan methyl ester (III-b)
5-methyl-L-tryptophan (4.365g, 20mmol) and 40mL of methanol are added into a 100mL three-neck flask with a magnetic stirring thermometer, thionyl chloride (3.569g, 30mmol) is slowly added dropwise under an ice bath at the temperature of-10 ℃ to ensure that the temperature of the reaction solution is below room temperature, after the dropwise addition is finished, the temperature is raised to reflux for esterification reaction, and the TLC monitoring reaction is finished. Cooling, concentrating to remove methanol, adding saturated sodium bicarbonate solution to basify until the pH value is 8-9, adding chloroform for extraction (3 × 20ml), taking an organic layer for washing (2 × 15ml), drying by anhydrous sodium sulfate, and concentrating to obtain 4.474g of 5-methyl-L-tryptophan methyl ester (III-b) which is yellow oily matter, wherein the yield is 96.3%, and the HPLC purity of the product is 98.27%.
Preparation of (hepta) N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-a)
Adding L-tryptophan methyl ester (2.183g, 10mmol) and tetrahydrofuran (20mL) into a 100mL three-neck flask with a magnetic stirring thermometer, adding pyridine (791mg, 10mmol) at room temperature, slowly dropwise adding trifluoroacetic anhydride (2.100g, 10mmol) at-10 ℃ in an ice bath, ensuring that the temperature of the reaction solution is below room temperature, turning to room temperature after the dropwise adding for acylation reaction, and monitoring the reaction end by TLC. The tetrahydrofuran is removed by concentration, 2.599g of white solid N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-a) is obtained after washing, filtering and drying, the yield is 82.7 percent and the HPLC purity of the product is 99.24 percent.
(VIII) preparation of N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-a)
L-tryptophan methyl ester (2.183g, 10mmol) and tetrahydrofuran (20mL) are added into a 100mL three-neck flask with a magnetic stirring thermometer, triethylamine (1.012g, 10mmol) is added at room temperature, trifluoroacetic anhydride (2.205g, 10.5mmol) is slowly added dropwise at-10 ℃ in an ice bath, the temperature of the reaction solution is ensured to be below the room temperature, the reaction solution is transferred to the room temperature after the addition is finished for acylation reaction, and the reaction is monitored by TLC to be finished. The tetrahydrofuran is removed by concentration, and 2.627g of white solid N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-a) is obtained after washing, filtering and drying, the yield is 83.6 percent, and the HPLC purity of the product is 99.60 percent.1H NMR(400MHz,DMSO-d6)δ10.90(s,1H),9.94(d,J＝7.6Hz,1H),7.54(d,J＝7.8Hz,1H),7.35(d,J＝8.1Hz,1H),7.16(d,J＝2.2Hz,1H),7.09(t,J＝7.2Hz,1H),7.00(t,J＝7.4Hz,1H),4.60(m,J＝9.6,7.9,5.1Hz,1H),3.67(s,3H),3.32(dd,J＝14.8,5.1Hz,1H),3.20(dd,J＝14.7,9.8Hz,1H).
Preparation of (nine) 5-methyl-N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-b)
A100 mL three-neck flask with a magnetic stirring thermometer is added with 5-methyl-L-tryptophan methyl ester (2.323g, 10mmol) and tetrahydrofuran 20mL, triethylamine (1.518g, 15mmol) is added at room temperature, trifluoroacetic anhydride (2.520g, 12mmol) is slowly added dropwise at-10 ℃ in an ice bath, the temperature of the reaction solution is ensured to be below the room temperature, the reaction solution is transferred to the room temperature for acylation reaction after the dropwise addition is finished, and the reaction is monitored by TLC to be finished. The tetrahydrofuran is removed by concentration, and 2.459g of white solid 5-methyl-N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-b) is obtained after washing, filtering and drying, the yield is 74.9 percent and the HPLC purity of the product is 99.31 percent.
(ten) preparation of 5-methyl-N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-b)
5-methyl-L-tryptophan methyl ester (2.323g, 10mmol) and tetrahydrofuran (20mL) are added into a 100mL three-neck flask with a magnetic stirring thermometer, pyridine (1.424g, 18mmol) is added at room temperature, trifluoroacetic anhydride (3.150g, 15mmol) is slowly added dropwise at-10 ℃ in an ice bath, the temperature of the reaction solution is ensured to be below the room temperature, the reaction solution is transferred to the room temperature for acylation reaction after the addition is finished, and the reaction is monitored by TLC to be finished. The tetrahydrofuran is removed by concentration, and 2.571g of white solid 5-methyl-N-alpha-trifluoroacetyl-L-tryptophan methyl ester (IV-b) is obtained after washing, filtering and drying, the yield is 78.3 percent and the HPLC purity of the product is 99.40 percent.
Preparation of (undec) N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (V-a)
A100 mL two-necked flask equipped with a magnetic stirrer and a thermometer was charged with N-alpha-trifluoroacetyl-L-tryptophan methyl ester (3.143g, 10mmol) and 30mL of acetonitrile, and then Boc anhydride (2.401g, 11mmol) and 4-pyrrolidinylpyridine (148mg, 1.0mmol) were added thereto at room temperature, followed by maintaining at room temperature and monitoring by TLC to complete the reaction. Water (20ml) was added, extraction was carried out with dichloromethane (2X 20ml), the organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated and purified by recrystallization to give 3.671g of N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (V-a) as a colorless transparent oil in 88.6% yield and 98.45% product HPLC purity.
Preparation of (dodeca) N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (V-a)
A100 mL two-neck flask with a magnetic stirring thermometer was charged with N-alpha-trifluoroacetyl group-L-tryptophan methyl ester (3.143g, 10mmol) and tetrahydrofuran 30mL, Boc anhydride (2.619g, 12mmol) and N, N-dimethyl-4-aminopyridine (73mg, 0.6mmol) were added at room temperature, respectively, the reaction was maintained at room temperature and the reaction was monitored by TLC for completion. 20ml of water is added, the mixture is extracted by ethyl acetate (2X 20ml), the organic phases are combined, dried by anhydrous sodium sulfate, filtered, concentrated and purified by recrystallization to obtain 3.535g of colorless transparent oily N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (V-a), the yield is 85.3 percent and the HPLC purity of the product is 98.56 percent.1H NMR(400MHz,DMSO-d6)δ10.00(d,J＝7.1Hz,1H),8.05(d,J＝8.2Hz,1H),7.64(d,J＝7.7Hz,1H),7.52(s,1H),7.34(t,J＝7.7Hz,1H),7.26(t,J＝7.5Hz,1H),4.73-4.66(m,1H),3.70(s,3H),3.32(dd,J＝14.9,4.6Hz,1H),3.18(dd,J＝14.9,10.3Hz,1H),1.61(s,9H).
(thirteen) preparation of 5-methyl-N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (V-b)
A100 mL two-necked flask equipped with a magnetic stirrer and a thermometer was charged with 5-methyl-N-alpha-trifluoroacetyl-L-tryptophan methyl ester (3.283g, 10mmol) and 30mL of acetonitrile, and then Boc anhydride (2.837g, 13mmol) and N, N-dimethyl-4-aminopyridine (220mg, 1.8mmol) were added thereto at room temperature, followed by maintaining at room temperature and monitoring by TLC to complete the reaction. 20ml of water was added, followed by extraction with ethyl acetate (2X 20ml), and the organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by recrystallization to give 3.359g of 5-methyl-N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (V-b) as a colorless transparent oil, and the yield was 78.4% and the product HPLC purity was 98.74%.
Preparation of (tetradecyl) N-in-tert-butoxycarbonyl-L-tryptophan (VI-a)
N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (4.144g, 10mmol) and 35mL of methanol were charged into a 250mL two-necked flask equipped with a magnetic stirrer and a thermometer, and potassium carbonate (2.764g, 20mmol) was dissolved in water (35mL) to prepare an aqueous potassium carbonate solution having a concentration of about 7%, and the aqueous potassium carbonate solution was added to the reaction mixture to conduct hydrolysis at room temperature, and the reaction was monitored by TLC to be completed. Concentrating to remove methanol, adding 75ml of ethyl acetate, adjusting the pH value of a water layer to about 6 by using 10% citric acid aqueous solution, fully shaking, extracting, drying and concentrating an organic layer, and recrystallizing and purifying a concentrated product to obtain 2.227g of white solid N-in-tert-butoxycarbonyl-L-tryptophan (VI-a), wherein the yield is 73.2% and the HPLC purity is 97.51%.
(fifteen) preparation of N-in-t-butyloxycarbonyl-L-tryptophan (VI-a)
N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (4.144g, 10mmol) and 75mL of methanol were charged into a 250mL two-necked flask equipped with a magnetic stirrer and a thermometer, potassium carbonate (4.146g, 30mmol) was dissolved in water (37mL) to prepare an aqueous solution of potassium carbonate having a concentration of about 10%, the aqueous solution of potassium carbonate was added to the reaction mixture to conduct hydrolysis at room temperature, and the reaction was monitored by TLC to be completed. Concentrating to remove methanol, adding 75ml of ethyl acetate, adjusting the pH value of a water layer to about 6 by using 10% citric acid aqueous solution, fully shaking, extracting, drying and concentrating an organic layer, and recrystallizing and purifying a concentrated product to obtain 2.502g of white solid N-in-tert-butoxycarbonyl-L-tryptophan (VI-a), wherein the yield is 82.2% and the HPLC purity of the product is 98.75%.1H NMR(400MHz,DMSO-d6)δ8.03(d,J＝8.1Hz,1H),7.67(d,J＝7.7Hz,1H),7.59(s,1H),7.32(t,J＝7.7Hz,1H),7.24(t,J＝7.4Hz,1H),3.47(s,1H),3.30-3.27(m,1H),2.99-2.93(m,1H),1.62(s,9H).
Preparation of (hexadec) 5-methyl-N-in-tert-butoxycarbonyl-L-tryptophan (VI-b)
5-methyl-N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (4.284gg, 10mmol) and 45mL of methanol were placed in a 250mL two-necked flask equipped with a magnetic stirrer and a thermometer, and then sodium hydroxide (800mg, 20mmol) was dissolved in water (15mL) to prepare an aqueous solution of sodium hydroxide having a concentration of about 5%, and then the aqueous solution of sodium hydroxide was added to the reaction mixture to conduct hydrolysis at room temperature, and the completion of the reaction was monitored by TLC. Concentrating to remove methanol, adding 45ml of dichloromethane, adjusting the pH value of a water layer to about 6 by using 10% citric acid aqueous solution, fully shaking, extracting, drying and concentrating an organic layer, and recrystallizing and purifying a concentrated product to obtain 1.728g of white solid 5-methyl-N-in-tert-butoxycarbonyl-L-tryptophan (VI-b), wherein the yield is 54.3% and the HPLC purity is 97.01%.
Preparation of (heptadecyl) 5-methyl-N-in-tert-butoxycarbonyl-L-tryptophan (VI-b)
5-methyl-N-alpha-trifluoroacetoxy-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (4.284g, 10mmol) and 50mL of methanol were charged into a 250mL two-necked flask equipped with a magnetic stirrer and a thermometer, and potassium carbonate (3.455g, 25mmol) was dissolved in water (20mL) to prepare an aqueous potassium carbonate solution having a concentration of about 15%, and then the aqueous potassium carbonate solution was added to the reaction mixture to conduct hydrolysis at room temperature, and the reaction was monitored by TLC to be completed. Concentrating to remove methanol, adding 50ml of dichloromethane, adjusting the pH value of a water layer to about 6 by using 10% citric acid aqueous solution, fully shaking, extracting, drying and concentrating an organic layer, and recrystallizing and purifying a concentrated product to obtain 2.555g of white solid 5-methyl-N-in-tert-butoxycarbonyl-L-tryptophan (VI-b), wherein the yield is 80.3% and the HPLC purity of the product is 98.42%.
Preparation of (octadecyl) N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-a)
In a 100mL two-necked flask equipped with a magnetic stirrer and a thermometer, N-in-t-butoxycarbonyl-L-tryptophan (3.044g, 10mmol) and 32mL of tetrahydrofuran were charged, sodium hydrogencarbonate (1.680g, 20mmol) was dissolved in water (32mL) to prepare an aqueous solution of sodium hydrogencarbonate having a concentration of about 5%, the aqueous solution of sodium hydrogencarbonate was added to the reaction mixture, after completion of mixing, 9-fluorenylmethyl-N-succinimidyl carbonate (3.373g, 10mmol) was added, the reaction was carried out while maintaining room temperature, and the reaction was monitored by TLC to be completed. Concentrating to remove tetrahydrofuran, adding ethyl acetate (2X 20ml) for extraction, combining organic phases, washing the organic phases with saturated saline (3X 15ml), drying with anhydrous sodium sulfate, concentrating to obtain white crystalline solid, recrystallizing and purifying white crystals, performing suction filtration and drying to obtain 4.250g of N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-a), wherein the yield is 80.7 percent, and the HPLC purity of the product is 98.80 percent.1H NMR(400MHz,DMSO-d6)δ12.97(s,1H),8.06(d,J＝8.5Hz,1H),7.89(dd,J＝17.7,7.8Hz,3H),7.71-7.59(m,4H),7.42-7.32(m,3H),7.31-7.21(m,3H),4.41-4.31(m,1H),4.25-4.16(m,3H),3.24(dd,J＝14.8,4.3Hz,1H),3.08(dd,J＝14.8,10.3Hz,1H),1.57(s,9H).
Preparation of (nineteen) N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-a)
In a 100mL two-necked flask equipped with a magnetic stirrer and a thermometer, N-in-t-butoxycarbonyl-L-tryptophan (3.044g, 10mmol) and 30mL of ethyl acetate were added, sodium carbonate (1.590g, 15mmol) was dissolved in water (30mL) to prepare an aqueous solution of sodium carbonate having a concentration of about 5%, the aqueous solution of sodium carbonate was added to the reaction mixture, after completion of the mixing, 9-fluorenylmethyl-N-succinimidyl carbonate (4.048g, 12mmol) was added, the reaction was carried out while maintaining room temperature, and the reaction was monitored by TLC to be completed. The reaction mixture was separated, and the organic phase was washed with water (2X 15ml), then with saturated brine (1X 15ml), dried over anhydrous sodium sulfate and concentrated to give 4.079g of N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-a) as a white crystalline solid in 77.5% yield and 99.10% purity by HPLC.
Preparation of (icosyl) 5-methyl-N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-b)
5-methyl-N-in-t-butoxycarbonyl-L-tryptophan (3.184g, 10mmol) and 19mL of ethyl acetate were placed in a 100mL two-necked flask equipped with a magnetic stirrer and a thermometer, sodium hydrogencarbonate (2.100g, 25mmol) was dissolved in water (19mL) to prepare an aqueous solution of sodium hydrogencarbonate having a concentration of about 10%, the aqueous solution of sodium hydrogencarbonate was added to the reaction mixture, and after completion of the mixing, 9-fluorenylmethyl-N-succinimidyl carbonate (3.711g, 11mmol) was added to the mixture, and the reaction was carried out while maintaining room temperature, and the reaction was monitored by TLC to be complete. The reaction mixture was separated, and the organic phase was washed with water (2X 15ml) and then with saturated brine (1X 15ml), dried over anhydrous sodium sulfate and concentrated to give 4.145g of 5-methyl-N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-b) as a white crystalline solid, in 76.7% yield and 98.43% product HPLC purity.
Example 2
The second synthetic scheme for preparing the tryptophan derivative medical intermediate (I) in the invention is as follows:
(I) preparation of L-Tryptophan methyl ester (III-a)
Preparation of L-Tryptophan methyl ester (III-a) in example 2 example 1 was repeated.
Preparation of (di) N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a)
L-tryptophan methyl ester (2.183g, 10mmol) and tetrahydrofuran (20mL) were charged into a 100mL two-necked flask equipped with a magnetic stirrer and a thermometer, sodium carbonate (1.272g, 12mmol) was dissolved in water (20mL) to prepare an aqueous solution of sodium carbonate having a concentration of about 6%, the aqueous solution of sodium carbonate was added to the reaction mixture, after completion of the mixing, N-benzylsuccinimide carbonate (2.492g, 10mmol) was added, the reaction was carried out while maintaining room temperature, and the reaction was monitored by TLC to be completed. The organic phase was washed with water (1X 10ml), brine (1X 10ml), dried, filtered and concentrated to give 3.401g of N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a) as a brown yellow oil with a yield of 96.5% and a product HPLC purity of 99.47%.
(III) preparation of N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a)
L-tryptophan methyl ester (2.183g, 10mmol) and 20mL of ethyl acetate were placed in a 100mL two-necked flask equipped with a magnetic stirrer and a thermometer, sodium carbonate (1.590g, 15mmol) was dissolved in water (14mL) to prepare an aqueous solution of sodium carbonate having a concentration of about 10%, the aqueous solution of sodium carbonate was added to the reaction mixture, after completion of the mixing, N-benzylsuccinimide carbonate (2.617g, 10.5mmol) was added, the reaction was carried out while maintaining room temperature, and the reaction was monitored by TLC to be completed. The organic phase was washed with water (1X 10ml), brine (1X 10ml), dried, filtered and concentrated to give 3.439g of N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a) as a brown yellow oil with a yield of 97.6% and a product HPLC purity of 99.75%. 1H NMR (400MHz, DMSO-d6) δ 10.90(s,1H),7.81(d, J ═ 7.8Hz,1H),7.53(d, J ═ 7.8Hz,1H),7.38(d, J ═ 8.0Hz,2H),7.34(t, J ═ 5.6Hz,2H),7.30(s,1H),7.19(d, J ═ 2.0Hz,1H),7.10(t, J ═ 7.1Hz,1H),7.01(t, J ═ 7.3Hz,1H),5.05-4.97(m,2H),4.38-4.31(m,1H),4.04(q, J ═ 7.1Hz,1H),3.63(s,3H),3.20(dd, 5, 14.5, 14H), 14.06 (J ═ 14.06 Hz, 14H).
Preparation of (tetra) N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a)
L-tryptophan methyl ester (2.183g, 10mmol) and tetrahydrofuran (20mL) were charged into a 100mL two-necked flask equipped with a magnetic stirrer and a thermometer, sodium carbonate (1.590g, 15mmol) was dissolved in water (10mL) to prepare an aqueous solution of sodium carbonate having a concentration of about 14%, the aqueous solution of sodium carbonate was added to the reaction mixture, after completion of the mixing, N-benzylsuccinimide carbonate (2.741g, 11mmol) was added, the reaction was carried out while maintaining room temperature, and the reaction was monitored by TLC to be completed. The organic phase was washed with water (1X 10ml), brine (1X 10ml), dried, filtered and concentrated to give 3.362g of N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a) as a brown yellow oil with a yield of 95.4% and a product HPLC purity of 99.58%.
Preparation of (penta) N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a)
L-tryptophan methyl ester (2.183g, 10mmol) and 20mL of ethyl acetate were placed in a 100mL two-neck flask equipped with a magnetic stirrer and a thermometer, sodium carbonate (2.120g, 20mmol) was dissolved in water (10mL) to prepare an aqueous sodium carbonate solution having a concentration of about 17%, the aqueous sodium carbonate solution was added to the reaction mixture, after completion of the mixing, N-benzylsuccinimide carbonate (2.991g, 12mmol) was added, the reaction was carried out while maintaining room temperature, and the reaction was monitored by TLC to be complete. The organic phase was washed with water (1X 10ml), brine (1X 10ml), dried, filtered and concentrated to give 3.320g of N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (VII-a) as a brown yellow oil with a yield of 94.2% and a product HPLC purity of 99.65%.
(VI) preparation of N-alpha-benzyloxycarbonyl-N-in-t-butoxycarbonyl-L-tryptophan methyl ester (VIII-a)
A100 mL two-necked flask equipped with a magnetic stirrer and a thermometer was charged with N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (3.524g, 10mmol) and 30mL of acetonitrile, and then Boc anhydride (2.619g, 12mmol) and 4-pyrrolidinylpyridine (119mg, 0.8mmol) were added thereto at room temperature, followed by maintaining at room temperature and monitoring by TLC to complete the reaction. 20ml of water was added, followed by extraction with ethyl acetate (2X 20ml), and the organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by recrystallization to give 4.051g of N-alpha-benzyloxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (VIII-a) as a colorless transparent oil, in 89.5% yield and 98.64% purity by HPLC.
(VII) preparation of N-alpha-benzyloxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (VIII-a)
A100 mL two-necked flask equipped with a magnetic stirrer and a thermometer was charged with N-alpha-benzyloxycarbonyl-L-tryptophan methyl ester (3.524g, 10mmol) and 30mL of tetrahydrofuran, and then Boc anhydride (2.401g, 11mmol) and N, N-dimethyl-4-aminopyridine (73.302mg, 0.6mmol) were added thereto at room temperature, followed by maintaining at room temperature and monitoring by TLC to complete the reaction. 20ml of water was added, followed by extraction with ethyl acetate (2X 20ml), and the organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by recrystallization to give 3.797g of N-alpha-benzyloxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (VIII-a) as a colorless transparent oil, with a yield of 83.9% and a product HPLC purity of 99.49%.1H NMR(400MHz,DMSO-d6)δ8.06(d,J＝8.2Hz,1H),7.92(d,J＝8.0Hz,1H),7.61(d,J＝7.7Hz,1H),7.58(s,1H),7.37-7.32(m,2H),7.31(d,J＝8.8Hz,2H),7.28(s,1H),7.26(s,1H),5.01(s,2H),4.41(m,J＝9.7,4.7Hz,1H),4.04(q,J＝7.1Hz,1H),3.66(s,3H),3.18(dd,J＝14.7,4.5Hz,1H),3.04(dd,J＝14.7,10.0Hz,1H),1.62(s,9H).
Preparation of (eight) N-in-t-butyloxycarbonyl-L-tryptophan methyl ester (IX-a)
A100 mL two-necked flask equipped with a magnetic stirrer and a thermometer was charged with N-alpha-benzyloxycarbonyl-N-in-t-butoxycarbonyl-L-tryptophan methyl ester (4.525g, 10mmol) and 40mL of methanol, and then 5% Pd/C (i.e., 226mg) was added thereto, and the reaction was carried out at room temperature under the participation of a hydrogen balloon with caution to displace the gas in the flask, and the completion of the reaction was monitored by TLC. Pd/C is removed by filtration and washing with methanol, the organic phase is concentrated, and the concentrated product is purified by recrystallization to obtain 1.614g of colorless transparent oily N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (IX-a), the yield is 50.7%, and the HPLC purity of the product is 99.40%.
Preparation of (nine) N-in-t-butyloxycarbonyl-L-tryptophan methyl ester (IX-a)
A100 mL two-necked flask with magnetic stirring and thermometer was charged with N-alpha-benzyloxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (4.525g, 10mmol) and 40mL of ethyl acetate, followed by 10% Pd/C (i.e., 453mg), in the presence of a hydrogen balloon at room temperatureThe reaction was allowed to proceed, with care being taken to displace the gas in the reaction flask and the end of the reaction monitored by TLC. Pd/C is removed by filtration and washing with ethyl acetate, the organic phase is concentrated, and the concentrated product is purified by recrystallization to obtain 2.697g of colorless transparent oily N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (IX-a), the yield is 84.7%, and the HPLC purity of the product is 99.35%.1H NMR(400MHz,DMSO-d6)δ8.04(d,J＝8.2Hz,1H),7.58(d,J＝7.6Hz,1H),7.50(s,1H),7.32(t,J＝7.1Hz,1H),7.24(t,J＝7.0Hz,1H),4.03(q,J＝7.1Hz,1H),3.67(dd,J＝7.0,6.0Hz,1H),3.58(s,3H),3.01(dd,J＝14.0,5.6Hz,1H),2.92-2.88(m,1H),1.63(s,9H).
Preparation of (ten) N-in-t-butyloxycarbonyl-L-tryptophan methyl ester (IX-a)
A100 mL two-necked flask equipped with a magnetic stirrer and a thermometer was charged with N-alpha-benzyloxycarbonyl-N-in-t-butoxycarbonyl-L-tryptophan methyl ester (4.525g, 10mmol) and 40mL of methanol, and then 10% Pd/C (i.e., 453mg) was added thereto, and the reaction was carried out at room temperature under the participation of a hydrogen balloon with caution to displace the gas in the reaction flask, and the completion of the reaction was monitored by TLC. Pd/C was removed by filtration and washing with methanol, the organic phase was concentrated, and the concentrated product was purified by recrystallization to give 2.426g of N-in-t-butoxycarbonyl-L-tryptophan methyl ester (IX-a) as a colorless transparent oil at a yield of 76.2% and a product HPLC purity of 99.53%.
Preparation of (undec) N-in-t-butyloxycarbonyl-L-tryptophan methyl ester (IX-a)
A100 mL two-necked flask equipped with a magnetic stirrer and a thermometer was charged with N-alpha-benzyloxycarbonyl-N-in-t-butoxycarbonyl-L-tryptophan methyl ester (4.525g, 10mmol) and 40mL of ethyl acetate, and then with 7% Pd/C (i.e., 317mg) added thereto, and the reaction was carried out at room temperature under the participation of a hydrogen balloon with caution to displace the gas in the flask, and the completion of the reaction was monitored by TLC. Pd/C is removed by filtration and washing with ethyl acetate, the organic phase is concentrated, and the concentrated product is purified by recrystallization to obtain 2.516g of colorless transparent oily N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (IX-a), the yield is 79.0%, and the HPLC purity of the product is 99.60%.
Preparation of (dodeca) N-in-tert-butoxycarbonyl-L-tryptophan (VI-a)
N-in-t-butoxycarbonyl-L-tryptophan methyl ester (3.184g, 10mmol) and 60mL of methanol were placed in a 250mL two-necked flask equipped with a magnetic stirrer and a thermometer, potassium carbonate (1.382g, 10mmol) was dissolved in water (20mL) to prepare an aqueous solution of potassium carbonate having a concentration of about 6%, and the aqueous solution of potassium carbonate was added to the reaction mixture to conduct hydrolysis at room temperature, and the reaction was monitored by TLC for completion. Concentrating to remove methanol, adding 60ml of ethyl acetate, adjusting the pH value of a water layer to about 6 by using 10% citric acid aqueous solution, fully shaking, extracting, drying and concentrating an organic layer, and recrystallizing and purifying a concentrated product to obtain 2.830g of white solid N-in-tert-butoxycarbonyl-L-tryptophan (VI-a), wherein the yield is 93.0% and the HPLC purity of the product is 98.42%.
(thirteen) preparation of N-in-tert-butoxycarbonyl-L-tryptophan (VI-a)
N-in-t-butoxycarbonyl-L-tryptophan methyl ester (3.184g, 10mmol) and 30mL of methanol were placed in a 250mL two-necked flask equipped with a magnetic stirrer and a thermometer, potassium carbonate (1.658g, 12mmol) was dissolved in water (15mL) to prepare an aqueous potassium carbonate solution having a concentration of about 10%, and the aqueous potassium carbonate solution was added to the reaction mixture to conduct hydrolysis at room temperature, followed by TLC to monitor completion of the reaction. Concentrating to remove methanol, adding 45ml of ethyl acetate, adjusting the pH value of a water layer to about 6 by using 10% citric acid aqueous solution, fully shaking, extracting, drying and concentrating an organic layer, and recrystallizing and purifying a concentrated product to obtain 2.654g of white solid N-in-tert-butoxycarbonyl-L-tryptophan (VI-a), wherein the yield is 87.2% and the HPLC purity of the product is 97.87%. Preparation of (tetradecyl) N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-a)
Preparation of N-alpha-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan (I-a) in example 2 example 1 was repeated.
Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
