One-pot formation of functionalised 2-piperidinones from arylidenecyanoacetates and methanolic ammonia via tandem reactions

Abstract

Aryl aldehydes react with ethyl cyanoacetate in methanolic ammonium acetate to expeditiously furnish, besides high yields of arylidenecyanoacetates, 4,6-diaryt-3,5-dicyano-5-ethoxycarbonyl-2-piperidinones in low yields. But preformed arylidenecyanoacetates react with methanolic ammonia to furnish the same functionalised 2-piperidinones in much better yields. The actual stereostructure of one of the products was determined by single crystal X-ray diffraction analysis, and novel tandem reactions occurring in one pot are proposed for the formation of the products.