DOI: 10.1021/acs.orglett.6c04269 ISSN: 1523-7060
Nickel-Catalyzed Enantioselective Carbo-Carbonylation of Alkenes Using Formic Acid as a CO Surrogate: Access to Oxindoles Bearing Chiral Quaternary Carbon
Krishnamoorthy Kathirvel, Govindasamy SekarAbstract
Carbonylation reactions typically rely on toxic carbon monoxide gas, often under pressurized conditions. Herein, we report an enantioselective nickel-catalyzed carbonylative difunctionalization of activated olefins using formic acid as a safe and operationally simple CO surrogate under mild conditions. The reaction employs a chiral phosphine-based ferrocene ligand to furnish ester-functionalized oxindoles bearing stereogenic quaternary carbon centers in high yields and enantioselectivities. Isotopic-labeling and XPS studies support in situ CO generation and trapping by an alkyl-nickel intermediate.