Asymmetric Synthesis of cis- and trans-2,5-disubstituted pyrrolidines from 3-oxo pyrrolidine 2-phosphonates:: Synthesis of (+)-preussin and analogs

Pyrrolidine enones, derived from 3-oxo pyrrolidine 2-phosphonates and a HWE reaction with aldehydes, on Luche reduction give pyrrolidine allylic alcohols. The alcohols on hydrogenation (Pd/H(2)) give cis-2,5-disubstituted pyrroliclines and on treatment with TFA-NaBH(3)CN undergo a hydroxy directed reduction to trans-2,5-disubstituted pyrrolidines.