Polyphosphoric Acid-Promoted Efficient Synthesis of Cinnamides via Aldol Condensation of Amide

Cinnamides are common core structures that exist in a great number of pharmaceuticals and natural products. The development of efficient methods for preparing cinnamides is in great need. We report herein an efficient polyphosphoric acid (PPA)-promoted direct aldol condensation of an amide for the convenient and straightforward preparation of cinnamides. A variety of cinnamides were obtained in moderate-to-excellent yields (65–89%). This strategy features the use of equivalent amides and a short reaction time.