Synthesis of 3-Phenyl-4-piperidones from Acetophenone by Shapiro and Aza-Michael Reactions and Their Further Derivatization

The Shapiro reaction of acetophenone is the key in a convenient three-step access to a divinyl ketone which is further transformed by double aza-Michael reactions with primary amines into N-substituted 3-phenyl-4-piperidones. In the case of N-benzyl and N-allyl derivatives, the piperidine nitrogen atom can be deprotected and further functionalized, for example, by carboxamide, carbamate, or urea formation.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)