Visible-Light-Promoted Iron(II)/Lewis Base Catalysis for the Alkylation of Morita–Baylis–Hillman Acetates Using Carboxylic Acids

A novel photoinduced Fe­(OTf)2/2,4,6-collidine-catalyzed alkylation of Morita–Baylis–Hillman (MBH) acetates using carboxylic acids in a regio- and stereoselective manner is reported. This method demonstrates a broad scope, encompassing various carboxylic acids and MBH acetates, including drugs and bioactive molecules, to synthesize densely functionalized cinnamates and acrylates. The reactions are performed in the green solvent dimethyl carbonate under oxidant-free conditions. Based on control experiments, a plausible mechanism involving an Fe­(II)–Fe­(III)–Fe­(II) cycle is proposed.