Organocatalytic Approach to Polysubstituted Piperidines and Tetrahydropyrans

Polysubstituted piperidines and tetrahydropyrans are synthesized from aldehydes and two classes of trisubstituted nitroolefins via an O-TMS protected diphenylprolinol catalyzed domino Michael addition/aminalization (or acetalization) process. This approach allows formation of four contiguous stereocenters in the piperidine or tetrahydropyran ring in one step with excellent enantioselectivity.