Chemistry of 4-fluoroglutamic acid. Part 2. Separation of the diastereomers on a large scale. Preparation of cis- and trans-4-fluoro-5-pyrrolidone-2-carboxylic acids (4-fluoropyroglutamic acids)

Article abstract of DOI:10.1016/S0022-1139(00)80033-0

Separation of the 4-fluoroglutamic acid diastereomers has been achieved by crystalization of the hydrochlorides of their dialkyl esters 1b and 2d.Subsesquent hydrolysis afforded the diastereomers 1a and 2a in 100percent steric purity.Conversion of the acids into the 5-methyl esters followed by treatment with ammonia gives rise to the trans and cis isomers of 4-fluoro-5-pyrrolidine-2-carboxylic acid, 3 and 4.NMR data are given.