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Method for preparing methyldopa through microwave basic hydrolysis 5-methyl-5-(3,4-dimethoxy benzyl) hydantoin

A technology of dimethoxybenzyl and dimethoxyphenyl, which is used in microwave alkali hydrolysis of 5-methyl-5-(3,4-dimethoxybenzyl)hydantoin to prepare methyl polyphenol In the field of Pakistan, it can solve problems such as difficulty in hydrolysis of NaOH lye

Active Publication Date: 2012-11-14
ZHEJIANG CHIRAL MEDICINE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, hydantoin compounds with aryl and alkyl groups at the 5-position are very difficult to hydrolyze with NaOH lye due to steric hindrance

Method used

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  • Method for preparing methyldopa through microwave basic hydrolysis 5-methyl-5-(3,4-dimethoxy benzyl) hydantoin
  • Method for preparing methyldopa through microwave basic hydrolysis 5-methyl-5-(3,4-dimethoxy benzyl) hydantoin

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Experimental program
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Effect test

Embodiment 1

[0027]In the reaction flask, add 4.3g (0.016mol) of 5-methyl-5-(3,4-dimethoxybenzyl)hydantoin, and place in a solution of 2.1gNaOH (0.053mol) dissolved in 17ml of water , the reaction mixture was placed in a chemical experiment temperature-controlled microwave instrument, and irradiated for 15 minutes at a microwave power of 250 watts. After cooling, adjust the pH to 4 with 6N hydrochloric acid, filter under reduced pressure to obtain a solid, wash with 2x5ml of ethanol, then dissolve in about 30-40ml of acetone, adjust the pH to 8.8 with ammonia water, and crystallize. Carefully add a small amount of glacial acetic acid to adjust the pH to 6, and keep the pH stable, then filter and separate to obtain the product DL-α-methyl-(3,4-dimethoxyphenyl)-α-alanine, and vacuum-dry at 80°C Dry. Yield 73.7%.

Embodiment 2

[0029] In the reaction flask, add 4.3g (0.016mol) 5-methyl-5-(3,4-dimethoxybenzyl) hydantoin, put 2.56gNaOH (0.064mol) in 17ml water solution , irradiate for 15 minutes at a microwave power of 250 watts. After cooling, adjust the pH to 4 with 6N hydrochloric acid, filter under reduced pressure to obtain a solid, wash with 2x5ml of ethanol, then dissolve in about 30-40ml of acetone, adjust the pH to 8.8 with ammonia water, and crystallize. Carefully add a small amount of glacial acetic acid to adjust the pH to 6, and keep the pH stable, then filter and separate to obtain the product DL-α-methyl-(3,4-dimethoxyphenyl)-α-alanine, and vacuum-dry at 80°C Dry. Yield 78.7%.

Embodiment 3

[0031] In the reaction flask, add 4.3g (0.016mol) 5-methyl-5-(3,4-dimethoxybenzyl) hydantoin, put 2.56gNaOH (0.064mol) in 17ml water solution Medium, 500 Wh, irradiated for 10 minutes. After cooling, adjust the pH to 4 with 6N hydrochloric acid, filter under reduced pressure to obtain a solid, wash with 2x5ml of ethanol, then dissolve in about 30-40ml of acetone, adjust the pH to 8.8 with ammonia water, and crystallize. Carefully add a small amount of glacial acetic acid to adjust the pH to 6, and keep the pH stable, then filter and separate to obtain the product DL-α-methyl-(3,4-dimethoxyphenyl)-α-alanine, and vacuum-dry at 80°C Dry. Yield 83.7%.

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Abstract

The invention relates to a method for preparing methyldopa or L-methyldopa through microwave basic hydrolysis 5-methyl-5-(3,4-dimethoxy benzyl) hydantoin. Various alkaline aqueous solutions with different concentrations are adopted to hydrolyze 5-methyl-5-(3,4-dimethoxy benzyl) hydantoin under different microwave power and radiation times to prepare DL-alpha-methyl-(3,4-dimethoxy benzyl)-alpha-aminopropionic acid salt which is hydrolyzed in an acid aqueous solution to prepare methyldopa[DL-alpha-methyl-(3,4-dimethoxy benzyl)-alpha-aminopropionic acid] or L-methyldopa[L-alpha-methyl-(3,4-dimethoxy benzyl)-alpha-aminopropionic acid]. When the method is used for hydrolyzing DL-alpha-methyl-(3,4-dimethoxy benzyl)-alpha-aminopropionic acid (or L-alpha-methyl-(3,4-dimethoxy benzyl)-alpha-aminopropionic acid), the molar ratio of a substrate and hydrogen bromide (Hbr) is 1:10-20, and the molar ratio of the substrate and chlorine hydride (HCl) is 1:10-30. The hydrolysis reaction is smooth when acid using amount is big, and disacidify pressure after the hydrolysis reaction is reduced when the acid using amount is small.

Description

technical field [0001] The technical field of the present invention belongs to chemically synthesized drug methyldopa [Methyldopa, α-methyl-(3,4-dihydroxyphenyl)-α-alanine, the same below] or synthetic chiral drug L-methyldopa One of the key steps in [L-methyldopa, L-α-methyl-(3,4-dihydroxyphenyl)-α-alanine, the same below]: hydrolysis of 5-methyl-5-(3 , 4-dimethoxybenzyl) hydantoin to prepare methyldopa reaction. Background technique [0002] L-Methyldopa is a catecholamine hormone in organisms and is a decarboxylase inhibitor [SLETA INGER M, CHEMERDA J M, W BOLL INGERF.Potent decarboxylase inhibitors.analogs of methyldopa[J].J Med Chem,1963,6(2 ): 1012103.], has antihypertensive effect, and is clinically used to treat hypertension [XU J M, ZHENG H J. Clinical application and evaluation of methyldopa[J]. Chin J New Drugs Clin Rem , 1990, 9(6):367-369.]. L-methyldopa is also one of the main drugs for the treatment of Parkinson's disease [Bronstein, J.M., Stereotactic Pall...

Claims

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Application Information

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IPC IPC(8): C07C227/16C07C229/36C07C227/24
Inventor 徐伟亮徐子河汪静黄有明
Owner ZHEJIANG CHIRAL MEDICINE CHEM
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