Synthesis of chiral beta(2,2,3)-3-amino-2-hydroxyalkanoates and 3-alkyl-3-hydroxy-beta-lactams by double asymmetric induction

Reactions of chiral (2S)-enolates of dioxolan-4-ones, derived from lactic, mandelic, and phenyllactic acids, with aliphatic (S-S)and (S-R)-tert-butylsulfinyl aldimines afforded conformationally restrained C2-disubstituted N,O-orthogonally protected 3-amino-2-hydroxyalkanoates in the form of N-sulfinyl protected 1'-aminodioxolan-4-ones. The product distribution showed that there is significant kinetic selectivity, due to the presence of 'matched' and 'mismatched' components, between the (S)-or (R)-tert-butylsulfinyl aldimines and the (2S)enolates of the 1,3-dioxolan-4-ones. Selective methoxide- induced removal of the acetal group of the N-sulfinyl-1'-aminodioxolanones yielded the corresponding N-sulfinyl protected methyl alkanoates. In addition, the selective acid-induced removal of the sulfinyl group of the N-sulfinyl-1'- aminodioxolanones provided the corresponding N-unprotected 1'-aminodioxolanones, whose base-induced cyclization afforded the corresponding beta-lactams.