Three-component synthesis of (E)-α,β-unsaturated amides of the piperine family

Selective formation of (E)-α,β-unsaturated amides by intermolecular three-component reaction between aldehydes, amines (1° or 2°) and ketenylidenetriphenylphosphorane (Ph3PCCO) is described. Natural amides such as fagaramide and piperines could be prepared from immediately available educts. The method is shown to be extendable to the preparation of thioesters from thiols and aldehydes.