One-Pot Lewis Acid Mediated Water-Promoted Transformation of Styrenes to α-Substituted Conjugated Enals.

We report herein an unusual one-pot preparation of α-benzyl-substituted conjugated enals via ZnCl 2 /LiCl/H 2 O-mediated transformation of styrenes. On the basis of experimental and computational studies, an underlying mechanism including electrophilic addition and hydride transfer with iminium cations has been proposed. The effect of the LiCl/ZnCl 2 /H 2 O combination on the reaction yield has been studied, demonstrating their participation in the activation and the key isomerization of an iminium electrophile.