Michael Addition of Malononitrile to α‐Acetylcinnamamides

Abstract The reaction of α‐acetylcinnamamides 7a–e with malononitrile using piperidine as the catalyst is described. When one or two equivalents of malononitrile are used, the 2‐amino‐4H‐pyran 6a or the polyfunctionalized carbocycles 9b–e, respectively, can be isolated as major products, depending on the experimental conditions. Compounds 9b–e apparently arise from a sequential Michael plus Knoevenagel addition of two molecules of malononitrile followed by Thorpe cyclization. The structure of 9b was determined by an X‐ray crystallographic analysis, which revealed a twisted cyclohexadiene ring with a characteristic crystal packing.