A novel approach for the asymmetric synthesis of (3S,4R)-3-amino-4-alkyl-2-piperidinones: conformationally constrained dipeptides

A straightforward method is developed for the synthesis of enantiopure (3S,4R)-3-amino-4-alkyl-2-piperidinone derivatives, six-membered lactam-bridged dipeptides, via highly diastereofacial selective 1,4-addition of organocuprate to the chiral oxazolidine α,β-unsaturated ester 1 as the key step.