Asymmetric synthesis of β-substituted α-methyl-β-amino esters by Mannich reaction of (S,S)-(+)-pseudoephedrine acetamide derived enolate with imines

[GRAPHICS] 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.