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)