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

A novel photoinduced Fe(OTf)<sub>2</sub>/2,4,6-collidine-catalyzed\nalkylation of Morita–Baylis–Hillman (MBH) acetates using\ncarboxylic acids in a regio- and stereoselective manner is reported.\nThis method demonstrates a broad scope, encompassing various carboxylic\nacids and MBH acetates, including drugs and bioactive molecules, to\nsynthesize densely functionalized cinnamates and acrylates. The reactions\nare performed in the green solvent dimethyl carbonate under oxidant-free\nconditions. Based on control experiments, a plausible mechanism involving\nan Fe(II)–Fe(III)–Fe(II) cycle is proposed.