Annulation chemistry based on tandem Michael addition-enamine formation – An improved method for the preparation of 1-substituted-2,3,5,6,7,8-hexahydroquinolin-4(1H)-ones

Abstract

The reaction of 2-(but-2-enoyl)cyclohexan-1-one 2 with primary amines affords 1-substituted-2,3,5,6,7,8-hexahydroquinolin-4(1H)-ones through a tandem Michael addition/enamine formation reaction sequence at room temperature in high yields. Reaction times are greatly reduced (4–24 h vs. 1–2 h; reflux versus room temperature) when powdered 4 Å sieves are used.