Synthesis of chiral β2,2,3-3-amino-2-hydroxyalkanoates and 3-alkyl-3-hydroxy-β-lactams by double asymmetric induction

Abstract Reactions of chiral (2 S )-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 (2 S )-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 β-lactams.