Asymmetric Synthesis of β-Substituted α-Methyl-β-amino Esters by Mannich Reaction of (S,S)-(+)-Pseudoephedrine Acetamide Derived Enolate with Imines

[reaction: see text]. The reaction of an (S,S)-(+)-pseudoephedrine acetamide based enolate with several imines afforded smoothly and with full stereochemical control a series of beta-substituted alpha-methyl-beta-aminoamides that upon hydrolysis/esterification afforded the corresponding beta-aminoester derivatives in good yields and in almost enantiomerically pure form.