Superacidic Activation of α,β‐Unsaturated Amides and Their Electrophilic Reactions

Abstract

Abstract The electrophilic reactivity of α,β‐unsaturated amides towards weak nucleophiles such as arenes and cyclohexane, initiated either with triflic acid (CF 3 SO 3 H) or with excess AlCl 3 , has been studied. The amides generally condense readily with aromatics in the presence of AlCl 3 to give 3‐arylpropionamides and related compounds in excellent yields, while some amides also undergo selective ionic hydrogenation with cyclohexane to give saturated amides. The proposed mechanism of these reactions involves dicationic intermediates (superelectrophiles). The direct observation of a dicationic species (by low‐temperature NMR) is reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)