Enantiopure N-sulfinyl-delta-amino-beta-ketoesters and isoquinolones, prepared from sulfinimines (N-sulfinyl imines) are a new class of polyfunctionalized chiral building blocks. These building blocks provide easy access to enantiomerically pure, functionalized piperidines and tetrahydroisoquinolines with a minimum of chemical manipulation and protecting-group chemistry. (C) 2002 Wiley Periodicals, Inc.