title: Preparation of (R) and (S) alpha methyldopa from a chiral hydantoin containing the alpha phenylethyl group.
abstract: Chiral hydantoin (S)-1 was prepared in good yield from phenyl isocyanate and N-[(S)-alpha-phenylethyl]glycinate, (S)-3. Enolate (S)-1-Li was methylated in high yield and good diastereoselectivity. In contrast, a second alkylation reaction of methylated enolate (S)-4-Li proceeded with essentially no diastereoselectivity. Nevertheless, dialkylated hydantoins, (S,S)-7 and (S,R)-7, could be readily separated by flash chromatography and subsequent hydrolysis of either derivative afforded the desired (S)-L-alpha-methyldopa or (R)-D-alpha-methyldopa in good yield.
authors.affiliation: Departamento de Química, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, D.F., México.
authors.forename: José Luis
authors.initials: JL
authors.lastname: León-Romo
authors.forename: Claudia I
authors.initials: CI
authors.lastname: Virues
authors.forename: Judit
authors.initials: J
authors.lastname: Aviña
authors.forename: Ignacio
authors.initials: I
authors.lastname: Regla
authors.forename: Eusebio
authors.initials: E
authors.lastname: Juaristi
mesh_terms: D000478:Alkylation; D000959:Antihypertensive Agents / Q000138:chemical synthesis* / Q000737:chemistry; D006827:Hydantoins / Q000737:chemistry*; D007202:Indicators and Reagents; D008750:Methyldopa / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D013237:Stereoisomerism
chemical_list: D000959:Antihypertensive Agents; D006827:Hydantoins; D007202:Indicators and Reagents; D008750:Methyldopa