CN115286554A - Preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan - Google Patents
Preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan Download PDFInfo
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Abstract
The application relates to the technical field of protected amino acid synthesis, in particular to a preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan, which comprises the following steps of S1: taking L-tryptophan as a raw material, and condensing to obtain L-tryptophan ester hydrochloride; s2: condensing the S1 product with triphenyl carbinol under the action of a reagent A to obtain N-alpha-trityl-L-tryptophan ester; s3: condensing the S2 product with tert-butoxycarbonyl anhydride to obtain N-alpha-trityl-N-in-tert-butoxycarbonyl-L-tryptophan ester; s4: removing trityl from the product obtained in the step S2 under the action of acid to obtain N-in-tert-butoxycarbonyl-L-tryptophan ester; s5: performing alkaline hydrolysis on the product obtained in the step S4 to obtain N-in-tert-butoxycarbonyl-L-tryptophan; s6: and condensing the product obtained in the step S5 and 9-fluorenylmethoxycarbonyl to obtain a target product. The method can prepare the final product with higher yield under the production conditions of low cost and low requirements on production equipment, and is more suitable for industrial production.
Description
Technical Field
The application relates to the technical field of protected amino acid synthesis, in particular to a preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan.
Background
The structural formula of the N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan is shown as a formula (I), the structural formula is the tryptophan protected by fluorenylmethoxycarbonyl and tert-butoxycarbonyl, the English abbreviation is Fmoc-Trp (Boc) -OH, the molecular formula is C31H30N2O6, the molecular weight is 526.58, and the cas number is 143824-78-6.
N-alpha-9-fluorenylmethyloxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan is a common intermediate for synthesizing polypeptide medicaments such as the hypoglycemic agent somaglutide, the quality osteoporosis medicament teriparatide and the like.
Chinese patent CN202110672717 reports the synthesis of N-alpha-fluorenylmethyloxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan 1, and the target product is obtained by using L-tryptophan as a starting material through esterification, amidation, tert-butoxycarbonyl protection, hydrolysis, amidation or esterification, amidation, tert-butoxycarbonyl protection, hydrogenation, hydrolysis and amidation. Scheme 1 disclosed therein uses trifluoroacetyl as a temporary protecting group, expensive trifluoroacetic anhydride is required, and trifluoroacetyl is relatively difficult to remove, requiring more severe conditions to affect the t-butoxycarbonyl protecting group. Scheme 2 disclosed therein uses benzyloxycarbonyl as a temporary protecting group, and the removal of the protecting group requires high-pressure catalytic hydrogenation, high-pressure hydrogenation equipment and an expensive noble metal catalyst.
Therefore, in view of the above prior art, the inventors considered that it is necessary to provide a method for producing N-alpha-9-fluorenylmethoxycarbonyl-N-in-t-butoxycarbonyl-L-tryptophan, which is capable of achieving both high yield and lower cost and has lower requirements for production facilities.
Disclosure of Invention
In order to overcome the defects of high cost and high requirement on equipment of the existing preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan, the application provides a preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan, which can prepare N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan with higher yield under the production conditions of low cost and low requirement on production equipment.
The application provides a preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan, which adopts the following technical scheme:
a preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan comprises the following steps:
(1) In the formula (II)
L-tryptophan as a starting material is condensed with R-OH to obtain a compound shown as a formula (III)
R in the R-OH is methyl or ethyl;
(2) Condensing L-tryptophan ester hydrochloride shown in a formula (III) with triphenylmethanol under the action of a reagent A to obtain a compound shown in a formula (IV)
The reagent A is one or the combination of a plurality of sulfuric acid, acetic acid and carboxylic anhydride;
(3) Condensing N-alpha-trityl-L-tryptophan ester shown as a formula (IV) with tert-butoxycarbonyl acid anhydride to obtain a compound shown as a formula (V)
N-alpha-trityl-N-in-t-butoxycarbonyl-L-tryptophan ester;
(4) Removing trityl group from N-alpha-trityl-N-in-t-butoxycarbonyl-L-tryptophan ester shown in formula (V) under the action of acid to obtain formula (VI)
N-in-tert-butoxycarbonyl-L-tryptophan as shown;
(5) Hydrolyzing the N-in-tert-butoxycarbonyl-L-tryptophan ester shown in the formula (VI) under alkaline to obtain the compound shown in the formula (VII)
Shown inN-in-t-butoxycarbonyl-L-tryptophan of (1);
(6) Condensing N-in-tert-butoxycarbonyl-L-tryptophan shown in a formula (VII) with 9-fluorenylmethoxycarbonyl to obtain a target product N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan; wherein R in the formula (III), the formula (IV), the formula (V) and the formula (VI) is methyl or ethyl introduced by the R-OH.
In the technical scheme, the amino group in the L-tryptophan ester hydrochloride shown in the formula (III) is protected by the triphenylmethanol, the triphenylmethanol is easy to obtain and is more economical in price than trifluoroacetic anhydride and N-benzyl succinimide carbonate, and more importantly, experiments prove that the protection and deprotection reaction of the triphenylmethanol is controlled under the production conditions of low cost and low requirement on production equipment, and the intermediate product and the final product can be obtained with higher yield and high purity, so that the preparation method of the N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan is easier to industrially realize mass production. In addition, in the protection reaction of the triphenylmethanol, the reagent A is added, so that water generated by the reaction can be continuously consumed, the reaction with the raw material and the intermediate product is avoided, the condensation reaction of the triphenylmethanol and the L-tryptophan ester hydrochloride can be promoted to be more thorough, and the effect of improving the yield of the final product is finally achieved; in the reaction of removing the trityl group, the reaction condition is mild, the possibility that the removal of the protection causes damage to the tert-butoxycarbonyl group is reduced, and the generation of byproducts is reduced.
Implementations may include any or all of the following features.
In another embodiment, the molar ratio of the triphenylmethanol to the L-tryptophan ester hydrochloride in the step (2) is 1 to 1.5.
In another embodiment, the reaction temperature of step (2) is 0 to 30 ℃.
In another embodiment, the reaction temperature of step (2) is preferably 10-15 ℃, and the reaction time is 2-3 h.
In another embodiment, the acid in step (4) is one or more of formic acid, acetic acid and propionic acid.
In another embodiment, the amount of the acid used in step (4) is 5 to 10 times the amount of the N-alpha-trityl-N-in-t-butoxycarbonyl-L-tryptophan ester represented by formula (V).
In another embodiment, the reaction temperature in the step (4) is 30-60 ℃, and the reaction time is 3-6 h.
In another embodiment, the R-OH in the step (1) is a methanol or ethanol solution of hydrogen chloride, and the molar ratio of the hydrogen chloride to the L-tryptophan of the formula (II) is 1.2-2.0.
In another embodiment, in the step (3), a reagent B is added, and the reagent B is one or a combination of triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine and diisopropylethylamine.
In another embodiment, the 9-fluorenylmethoxycarbonyl in the step (6) is 9-fluorenylmethyl-N-succinimidyl carbonate or 9-fluorenylmethyloxy chloroformate, and the reagent C is added in the step (6), and the reagent C is one or a combination of sodium hydroxide, sodium carbonate, sodium bicarbonate and potassium carbonate.
In summary, the application provides a method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan, the synthetic route of the method is simplified, and the yield and purity of the intermediate product and the final product prepared by the method can be maintained at a higher level. In addition, the amino protection reagent triphenyl carbinol screened by the method can be subjected to condensation reaction with L-tryptophan ester hydrochloride under the promotion of the reagent A and through conventional reaction conditions and reaction equipment, and the yield of the step is improved to be more than 86%; the subsequent removal condition of the triphenylmethanol is milder and controllable, the removal operation has no special equipment requirement and danger, and the yield of the intermediate product N-in-tert-butoxycarbonyl-L-tryptophan ester obtained by deprotection reaches 89%. The method has advantages in cost control, operation difficulty, requirements on production equipment, production safety, intermediate product yield and final product yield, and is more suitable for industrial production. In addition, the preparation method has the highest reaction temperature of 60 ℃ and the lowest reaction temperature of 0 ℃, so that the production process does not use overhigh or overlow reaction temperature, and has the advantages of energy conservation and environmental protection.
Drawings
FIG. 1 is a flow chart of a method of preparation of the present application;
FIG. 2 is a hydrogen spectrum of the final product N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan of example 1.
Detailed Description
The preparation of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan according to the present invention will be described in further detail with reference to FIG. 1.
The invention provides a preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan, which comprises the following synthetic route:
with reference to fig. 1, the method specifically comprises the following steps:
(1) Esterification: in the formula (II)
L-tryptophan as a starting material is condensed with R-OH to obtain the compound shown as the formula (III)
R in the R-OH is methyl or ethyl;
(2) Protection of trityl group: condensing L-tryptophan ester hydrochloride shown in a formula (III) with triphenylmethanol under the action of a reagent A to obtain a compound shown in a formula (IV)
The N-alpha-trityl-L-tryptophan ester is shown, wherein the reagent A is one or the combination of a plurality of sulfuric acid, acetic acid and carboxylic anhydride;
(3) Condensation: condensing N-alpha-trityl-L-tryptophan ester shown as the formula (IV) with tert-butoxycarbonyl anhydride to obtain the compound shown as the formula (V)
N-alpha-trityl-N-in-tert-butoxycarbonyl-L-tryptophan as shown;
(4) Removing trityl protection: removing trityl from N-alpha-trityl-N-in-tert-butoxycarbonyl-L-tryptophan ester shown in formula (V) under the action of acid to obtain the compound shown in formula (VI)
N-in-tert-butoxycarbonyl-L-tryptophan as shown;
(5) Hydrolysis: hydrolyzing the N-in-tert-butoxycarbonyl-L-tryptophan ester shown in the formula (VI) under alkaline to obtain the compound shown in the formula (VII)
N-in-tert-butoxycarbonyl-L-tryptophan as shown;
(6) Amidation: condensing N-in-tert-butyloxycarbonyl-L-tryptophan shown in the formula (VII) with 9-fluorenylmethoxycarbonyl to obtain a target product N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan; wherein R in the formula (III), the formula (IV), the formula (V) and the formula (VI) is methyl or ethyl introduced by the R-OH.
In the above step (1), R in the reactant R-OH is preferably methyl or ethyl, i.e. the reactant is methanol or ethanol, and in order to make the product of step (1) more stable, R-OH is further used as a methanol or ethanol solution of hydrogen chloride, the molar ratio of the hydrogen chloride to the L-tryptophan of the formula (ii) is 1.2 to 2.0, preferably 1.3 to 1.5. When the methanol or ethanol solution of hydrogen chloride is mixed with the L-tryptophan, the reaction system is controlled to be in a low-temperature environment, preferably a low-temperature environment of 0-5 ℃, so that the situation that the activity of the L-tryptophan is destroyed due to the heat generated in the reaction system by adding the hydrogen chloride can be reduced. When the esterification reaction in the step (1) is carried out, the esterification reaction temperature is not particularly limited, and the reflux temperature can be reached according to the conventional technical means in the field. The esterification reaction time in the step (1) is 2-8 h, preferably 4-5 h.
In the step (2), the reagent A is preferably acetic acid. The molar ratio of the triphenylmethanol to the L-tryptophan ester hydrochloride is 1-1.5, preferably 1.05-1.2. The reaction temperature of the step (2) is 0-30 ℃, preferably 10-15 ℃, and the reaction time is 2-3 h, so that the reaction condition is milder, and the generation of byproducts is reduced.
In the step (3), the molar ratio of the tert-butoxycarbonyl anhydride to the N-alpha-trityl-L-tryptophan represented by the formula (IV) is 1.0 to 1.2, preferably 1.02 to 1.05. The reaction in the step (3) is carried out under the catalysis of a catalyst, wherein the mole ratio of the catalyst to the N-alpha-trityl-L-tryptophan ester shown in the formula (IV) is preferably 0.01-0.2, and preferably 0.05-0.10. The reagent B added in the step (3) can promote the forward direction of the reaction in the step (3) and plays a role in improving the yield of the intermediate product, and the reagent B is one or a combination of more of triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine and diisopropylethylamine, and preferably is triethylamine. The reaction solvent in the step (3) is one or more of dichloromethane and 1, 2-dichloroethane, and dichloromethane is preferred. The reaction temperature of the step (3) is 0-30 ℃, preferably 10-15 ℃, and the reaction time is 3-6 h, preferably 4-5 h.
In the step (4), the acid is one of formic acid, acetic acid and propionic acid, preferably acetic acid, and the amount of the acid is 5 to 10 times, preferably 6 to 8 times that of the N-alpha-trityl-N-in-t-butoxycarbonyl-L-tryptophan ester represented by the formula (V). The reaction temperature of the step (4) is 30-60 ℃, preferably 40-50 ℃, and the reaction time is 3-6 hours, preferably 4-5 hours. Through the control of reaction temperature and reaction time, the trityl protecting group is relatively slowly deprotected under relatively mild conditions, so that the generation of by-products can be reduced as much as possible, and the activity of the intermediate product can be protected.
In the step (5), the alkaline condition of the hydrolysis reaction is provided by one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate and potassium carbonate. And (5) carrying out reaction in a solvent, wherein the solvent is one or more of methanol, ethanol, isopropanol and tetrahydrofuran, and methanol or ethanol is preferred. The reaction temperature of the step (5) is 10-40 ℃, preferably 20-30 ℃, and the reaction time is 2-5 h, preferably 3-4 h.
In the above step (6), the 9-fluorenylmethoxycarbonyl is 9-fluorenylmethyl-N-succinimidyl carbonate or 9-fluorenylmethyloxycarbonyl chloroformate, preferably 9-fluorenylmethyl-N-succinimidyl carbonate. And (3) reacting in a solvent, wherein the solvent is one or more of acetone, tetrahydrofuran, acetonitrile and the like, and acetone is preferred. And (3) adding a reagent C in the step (6), wherein the reagent C is one or a combination of several of sodium hydroxide, sodium carbonate, sodium bicarbonate and potassium carbonate, preferably sodium carbonate, and the addition of the solvent C is helpful for promoting the reaction in the step (6) and can improve the yield of the final product. The reaction temperature of the step (6) is 0-30 ℃, preferably 10-20 ℃, and the reaction time is 6-10 h, preferably 7-8 h.
The preparation of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan according to the present invention will be described in further detail with reference to the following examples.
Example (b):
the present application will be described in further detail with reference to specific examples.
The embodiment discloses a preparation method of N-alpha-9-fluorenylmethyloxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan, and the synthetic route is as follows:
the specific synthesis steps are as follows:
(1) Esterification: preparation of L-tryptophan methyl ester hydrochloride
Into a dry 2L four-necked flask, 400g of anhydrous methanol and 100g of (II) L-tryptophan were added. The temperature is reduced to 5 ℃, and 160g of 30 percent hydrogen chloride-methanol solution is added dropwise. After the dropwise addition, the reaction was carried out under reflux for about 4 hours. And (4) controlling the sample liquid phase until the raw materials disappear, and finishing the reaction. Distillation under reduced pressure was carried out until dryness to give 118.7g of L-tryptophan methyl ester hydrochloride (III) as a white solid with a purity of 99.4% and a yield of 95.1%. MS M/z 219.2 (M + H) +,1HNMR (DMSO-d 6, 400MHz) δ 8.04 (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), 3.01 (dd, J =14.0,5.6Hz, 1H), 1.92-2.88 (M, 1H).
(2) Protection of trityl group: preparation of N-alpha-trityl-L-tryptophan methyl ester 4
118.7g of L-tryptophan methyl ester hydrochloride (III), 2700g of isopropyl acetate and 129g of acetic anhydride prepared in the step (1) are sequentially added into a dry 5L four-neck flask, stirred and cooled to the material temperature of 15 ℃. The temperature of the reaction system is controlled to be 15 ℃, the isopropyl acetate solution of the triphenylmethanol is dripped, and the dripping is finished in about 1 hour, and the isopropyl acetate solution of the triphenylmethanol is prepared by dissolving 160g of the triphenylmethanol in 480g of isopropyl acetate. After the dropwise addition, the temperature is kept at 15 ℃ for reaction for 3 hours, and the reaction is finished after the raw materials disappear during sampling. Washing with 1000mL saturated sodium bicarbonate solution, separating, discarding water phase, concentrating organic phase until a large amount of white crystals precipitate, adding 340g water, stirring for 30 min, filtering, and collecting filter cake. After the filter cake was dried, 185.5g of white solid N-alpha-trityl-L-tryptophan methyl ester (IV) was obtained with a purity of 99.1% and a yield of 86.4%. MS M/z:461.2 (M + H) +,1H NMR (DMSO-d 6, 400MHz) δ:8.04 (d, J =8.2Hz, 1H), 7.58 (d, J =7.6Hz, 1H), 7.50 (s, 1H), 7.33 (dd, J =7.2,7.0Hz, 6H), 7.32 (t, J =7.1Hz, 1H), 7.29 (dd, J =7.2,7.0Hz, 3H), 7.28 (d, J = 7.111H, 6H), 7.24 (t, J =7.0Hz, 1H), 4.03 (q, J =7.1Hz, 1H), 3.67 (dd, J =7.0,6.0Hz, H), 3.58 (s, 3H), 3.01 (dd, 14.0, 1H), 1.88H, 1-1M H).
(3) Condensation: preparation of N-alpha-trityl-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester
185.5g of N-alpha-trityl-L-tryptophan methyl ester (IV) prepared in the step (2) and 2700g of dichloromethane are sequentially added into a clean 3L four-neck flask, 55g of triethylamine and 9.3g of 4- (N, N-dimethylamino) pyridine are added under stirring, and the temperature is reduced to 15 ℃. The temperature of the reaction system was controlled at 15 ℃ and 118g of di-tert-butyl dicarbonate was slowly added dropwise over about 2 hours. After the dropwise addition, the temperature is maintained at 15 ℃ for reaction for 4 hours, and the reaction is finished after the raw materials disappear during sampling. The pH was adjusted to acidity with an aqueous citric acid solution, and the organic phase was concentrated to remove methylene chloride, whereby 151.9g of N-alpha-trityl-N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (V) was obtained as a yellow oily substance with a purity of 98.5% and a yield of 67.2%. MS M/z:561.3 (M + H) +,1H NMR (DMSO-d 6, 400mhz) δ:8.04 (d, J =8.2hz, 1h), 7.58 (d, J =7.6hz, 1h), 7.50 (s, 1H), 7.33 (dd, J =7.2,7.0hz, 6h), 7.32 (t, J =7.1hz, 1h), 7.29 (dd, J =7.2,7.0hz, 3h), 7.28 (d, J = 7.117, 6h), 7.24 (t, J =7.0hz, 1h), 4.03 (q, J =7.1hz, 1h), 3.67 (s, J =7.0,6.0hz, 1h), 3.58 (s, 3H), 3.01 (dd, J =14.0, 6h), 1.88H, 1.63H, 1.88H, 1.63H, 1.8H, 1H, 1.63H, 1H, and 1.63H.
(4) Removing trityl protection: preparation of N-in-tert-butoxycarbonyl-L-tryptophan methyl ester
151.9g of N-alpha-trityl-N-in-t-butoxycarbonyl-L-tryptophan methyl ester (V) and 1960g of acetic acid were put into a 3L four-necked flask and stirred. The system was then warmed to 45 ℃ and reacted for 4 hours. And (5) controlling the reaction until the raw materials disappear in sampling, and finishing the reaction. Concentrating acetic acid to dryness under reduced pressure, adding 1000g of ethyl acetate and 500g of water, stirring, washing, removing a water layer, washing an organic layer for 3 times by using 500ml of 5% sodium bicarbonate aqueous solution, drying an organic phase by using anhydrous sodium sulfate, filtering, concentrating 2/3 of ethyl acetate, adding 200ml of petroleum ether for crystallization, filtering and drying a solid to obtain 79.1g of N-in-tert-butoxycarbonyl-L-tryptophan methyl ester (VI), wherein the purity is 98.2% and the yield is 91.7%. MS M/z 319.2 (M + H) +,1H NMR (DMSO-d 6, 400MHz) δ 8.04 (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), 1.92-2.88 (M, 1H), 1.63 (s, 9H).
(5) Hydrolysis: preparation of N-in-tert-butoxycarbonyl-L-tryptophan
79.1g of N-in-t-butoxycarbonyl-L-tryptophan methyl ester (VI) and 1000g of methanol were sequentially added to a 3L four-necked flask and dissolved by stirring. Then, 1000g of water was added to the reaction system. Controlling the temperature of the ice water bath to react, controlling the pH to be less than 13, dropwise adding liquid alkali, and carrying out saponification reaction for 3 hours. After the reaction was completed, 2/3 of the methanol was concentrated under reduced pressure. Hydrochloric acid was added to the concentrated residue to adjust the pH to =4, and a large amount of solid was precipitated. Filtering, and washing the filter cake three to four times with water. Collecting and drying the filter cake to obtain the N-in-tert-butoxycarbonyl-L-tryptophan (VII) 67.3g, purity 98.4% and yield 89%. MS M/z 303.2 (M-H) - ；1H NMR(DMSO-d6,400MHz)δ:8.04(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),3.01(dd,J＝14.0,5.6Hz,1H),1.92-2.88(m,1H),1.63(s,9H)。
(6) Amidation: preparation of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan
67.3g of N' -t-butoxycarbonyl-L-tryptophan (VII), 200g of acetone and 200g of water were added in a 3L four-necked flask, and a 10% sodium carbonate solution was added dropwise while maintaining the system pH =8-9, and an acetone solution of 9-fluorenylmethyl-N-succinimidyl carbonate was added dropwise. 82g of 9-fluorenylmethyl-N-succinimidyl carbonate and 200g of acetone in an acetone solution of 9-fluorenylmethyl-N-succinimidyl carbonate, and reacting for 8 hours at the reaction temperature of 15 ℃ to finish the reaction. 2/3 of the acetone was concentrated off, 1000g of ethyl acetate was added after the concentration was completed, then the organic phase was separated, hydrochloric acid was added to adjust PH =4, and the organic phase was washed 3 times with saturated brine. After 2/3 of ethyl acetate is concentrated, petroleum ether is added into the system to be stirred and crystallized, and the powdery product N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan (I) is obtained by filtering and drying, wherein the purity is 99.5 percent, and the yield is 77.7 percent. MS M/z 525.2 (M-H) - ； 1 H NMR(DMSO-d 6 400 MHz) δ 8.04 (d, J =8.2hz, 1h), 7.92 (d, J =8.0hz, 1h); 7.61 (d, J =7.7hz, 1h); 7.58 (s, 1H), 7.50 (s, 1H), 7.32 (t, J =7.1hz, 1h), 7.24 (t, J =7.0hz, 1h), 5.01 (s, 2H), 4.41 (m, 1H), 4.03 (q, J =7.1hz, 1h), 3.67 (dd, J =7.0,6.0hz, 1h), 3.18 (dd, J =14.7,4.5hz, 1h), 3.04 (dd, J =14.7,10.0hz, 1h), 1.63 (s, 9H). FIG. 2 shows a hydrogen spectrum of the final product of the reaction of this step, N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan.
The above are preferred embodiments of the present application, and the scope of protection of the present application is not limited thereto, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (10)
1. A preparation method of N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan is characterized by comprising the following steps:
(1) In the formula (II)
L-tryptophan as a starting material is condensed with R-OH to obtain the compound shown as the formula (III)
R in the R-OH is methyl or ethyl;
(2) Condensing L-tryptophan ester hydrochloride shown in a formula (III) with triphenylmethanol under the action of a reagent A to obtain a compound shown in a formula (IV)
The N-alpha-trityl-L-tryptophan ester is shown, wherein the reagent A is one or the combination of a plurality of sulfuric acid, acetic acid and carboxylic anhydride;
(3) Condensing N-alpha-trityl-L-tryptophan ester shown as a formula (IV) with tert-butoxycarbonyl acid anhydride to obtain a compound shown as a formula (V)
N-alpha-trityl-N-in-t-butoxycarbonyl-L-tryptophan ester;
(4) Removing trityl from N-alpha-trityl-N-in-tert-butoxycarbonyl-L-tryptophan ester shown in formula (V) under the action of acid to obtain the compound shown in formula (VI)
N-in-tert-butoxycarbonyl-L-tryptophan as shown;
(5) Hydrolyzing the N-in-tert-butoxycarbonyl-L-tryptophan ester shown in the formula (VI) under alkaline condition to obtain the compound shown in the formula (VII)
N-in-tert-butoxycarbonyl-L-tryptophan as shown;
(6) Condensing N-in-tert-butyloxycarbonyl-L-tryptophan shown in the formula (VII) with 9-fluorenylmethoxycarbonyl to obtain a target product N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butyloxycarbonyl-L-tryptophan; wherein R in the formula (III), the formula (IV), the formula (V) and the formula (VI) is methyl or ethyl introduced by the R-OH.
2. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan as claimed in claim 1, wherein the molar ratio of the triphenylmethanol to the L-tryptophan ester hydrochloride in the step (2) is 1 to 1.5.
3. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan as claimed in claim 2, wherein the reaction temperature in the step (2) is 0-30 ℃.
4. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan as claimed in claim 3, wherein the reaction temperature in the step (2) is preferably 10-15 ℃ and the reaction time is 2-3 h.
5. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan as claimed in claims 1 to 4, wherein the acid in the step (4) is one or more of formic acid, acetic acid and propionic acid.
6. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan according to claim 5, wherein the amount of the acid used in the step (4) is 5 to 10 times the amount of the N-alpha-trityl-N-in-tert-butoxycarbonyl-L-tryptophan ester represented by the formula (V).
7. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan as claimed in claim 6, wherein the reaction temperature in the step (4) is 30-60 ℃ and the reaction time is 3-6 h.
8. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan as claimed in claim 1, wherein the molar ratio of the hydrogen chloride to the L-tryptophan of the formula (II) in the step (1) is 1.2-2.0.
9. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan according to claim 1, wherein a reagent B is added in the step (3), wherein the reagent B is one or a combination of triethylamine, tri-N-propylamine, triisopropylamine, tri-N-butylamine, triisobutylamine and diisopropylethylamine.
10. The method for preparing N-alpha-9-fluorenylmethoxycarbonyl-N-in-tert-butoxycarbonyl-L-tryptophan as claimed in claim 1, wherein the 9-fluorenylmethoxycarbonyl in the step (6) is 9-fluorenylmethyl-N-succinimidyl carbonate or 9-fluorenylmethoxycarbonyl chloroformate, and a reagent C is added in the step (6), wherein the reagent C is one or a combination of several of sodium hydroxide, sodium carbonate, sodium bicarbonate and potassium carbonate.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5773441A (en) * | 1995-08-21 | 1998-06-30 | Eli Lilly And Company | 2-acylaminopropanamides as growth hormone secretagogues |
| CN102911106A (en) * | 2012-11-13 | 2013-02-06 | 上海合全药物研发有限公司 | Preparation method of L-N-Boc-high tryptophan methyl ester |
| CN113402438A (en) * | 2021-06-17 | 2021-09-17 | 浙江工业大学 | Preparation method of tryptophan derivative medical intermediate |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5773441A (en) * | 1995-08-21 | 1998-06-30 | Eli Lilly And Company | 2-acylaminopropanamides as growth hormone secretagogues |
| CN102911106A (en) * | 2012-11-13 | 2013-02-06 | 上海合全药物研发有限公司 | Preparation method of L-N-Boc-high tryptophan methyl ester |
| CN113402438A (en) * | 2021-06-17 | 2021-09-17 | 浙江工业大学 | Preparation method of tryptophan derivative medical intermediate |
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| 上海第一医学院等: "《药物合成反应》", 化学工业出版社, pages: 462 * |
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