Carbo-Carboxylation of Alkenes via Intramolecular Heck Carbonylation Utilizing CO2 and Hydrosilane

Starting from diverse alkene-tethered aryl halides and silyl formate formed in situ from CO2 and PMHS (polymethylhydrosiloxane), the carbo-carboxylation of alkenes has been achieved using an easily accessible Pd/monophosphine ligand combination as the catalyst. This protocol provides competent access to construct a series of 2,3-dihydrobenzofurans, chromans, isochroman, indanes and tetralins bearing a β-acid moiety in moderate to excellent yield. Additionally, the example of domino carbo-carbonylation reactions has been demonstrated using diene-tethered aryl iodide as a starting material, forming an oxygen-containing bicyclic product in good yield. It is speculated that the carbo-carboxylation reaction of alkenes proceeds via a carbo-silyloxycarbonylation pathway.