ChemicalBook CAS DataBase List Methyldopa

Methyldopa synthesis

9synthesis methods

Product Name:Methyldopa
CAS Number:555-30-6
Molecular formula:C10H13NO4
Molecular Weight:211.22

Methyldopa, (-)-3-(3,4-dihydroxyphenyl)-2-methylalanine (22.2.5), is synthesized by a few methods that are only slightly different. The first method is from 3,4- dimethoxyphenylacetone, which undergoes a Strecker–Zelinski reaction using potassium cyanide and ammonium carbonate, to give 4-methyl-4-(3,4-dimethoxybenzylhydantoine (22.3.3), which is further hydrolyzed in the presence of barium hydroxide to give ()-3-(3,4-dimethoxyphenyl)-2-methylalanine (22.3.4). This undergoes acetylation at the amino group, and the racemic mixture is then separated using (-)-1-phenylethylamine. The isolated isomer is hydrolyzed using hydrobromic acid, which simultaneously removes the methoxy- and acetyl groups to give the desired (-)-3-(3,4-dihydroxyphenyl)-2-methylalanine (22.3.5) [8–10]. Alternative syntheses have been proposed.

Propanedioic acid, 2-[(3,4-dimethoxyphenyl)methyl]-2-methyl-, 1,3-dimethyl ester

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Yield:-

Steps:

Multi-step reaction with 3 steps
1: α-chymotrypsin / dimethylsulfoxide; H2O / 22 - 25 °C / potassium phosphate ( pH 7.0); with pig liver esterase the reaction rate is higher but the e.e. is lower
2: 1.) acyl azide formation, 2.) Curtius rearrangement
3: aq. HBr (48percent)

References:

Bjoerkling, Fredrik;Boutelje, John;Gatenbeck, Sten;Hult, Karl;Norin, Torbjoern [Tetrahedron Letters,1985,vol. 26,# 40,p. 4957 - 4958]