Enantioselective synthesis of 5-substituted- and 3,5-disubstituted-2-formylpyrrolidine derivatives, the key D-ring fragments of (−)-quinocarcin and (−)-10-decarboxyquinocarcin
The title synthesis was achieved starting from (S)-glutamic acid and (S)-pyroglutamic acid by featuring formation of an N-protected aminal, substitution of the methoxy group with cyanide anion, and reduction of the cyanide to an aldehyde as common key steps.
The Improved Synthesis of Enantiopure (S)-N-Arylmethyl-5-Oxoprolines
A mild procedure for the preparation of enantiopure N-alkylated (S)-(+)-5-oxoprolines 3a-r is described. The method starting from (S)-glutamic acid appears generally applicable to substrates with a wide range of substituents.