Asymmetric synthesis of (2S,3S)- and (2S,3R)-3-prolinomethionines: 3-Methylsulfanylmethyl-pyrrolidine-2-carboxylic acids

Article abstract of DOI:10.1016/S0957-4166(97)00203-6

The synthesis of 3-prolinomethionine can be easily achieved in a diastereoselective and enantioselective way via zinc-enolate cyclisation. After transmetallation by CuCN.2LiCl, the zinc-copper derivative was reached with S-methyl methanesulfonothioate leading in a 'one-pot' procedure, to N-(α-methylbenzyl)-3-prolinomethinine benzyl ester. The α-methylbenzyl group was transformed in vinyl-oxycarbonyl and tertiobutyl-oxycarbonyl groups successively. Reprotonation of cis Voc prolinomethionine enolate at low temperature yielded the enantiomerically pure trans diastereoisomer.