Rh(III)-Catalyzed C-H Activation/Regiospecific Annulation Cascade of Benzoic acids with Propargyl Acetates to Unusual 3-Alkylidene-Isochromanones

A Rh(III)-catalyzed C-H activation and regiospecific annulation cascade of benzoic acid with propargyl acetate was developed to produce an unreported 3-alkylidene-isochromanone scaffold. The biggest merit of this reaction is achieving the regioselective control in the alkyne insertion and precise removal of acetyl group to eventually form 3-alkylidene-isochromanone scaffolds possessing an unusual exocyclic double bond with moderate to excellent yields (up to 93 %) under mild temperature along with broad generality and versatility.