A Regio- and Stereoselective Carbonylative Approach to Alkyl (Z)-2-[3-Oxoisobenzofuran-1-(3H)-ylidene]acetates

The first example of the oxidative carbonylation of 2-ethynylbenzoic acid derivatives, leading to alkyl (Z)-2-[3-oxoisobenzofuran-1-(3H)-ylidene]acetates in a regio- and stereoselective manner, is reported. Under the catalytic action of PdI 2 (2 mol%) in conjuction with KI (20 mol%), different 2-[(trimethylsilyl)ethynyl]benzoic acids were converted into the corresponding isobenzofuranones in high to excellent yields (70–98%). The proposed reaction mechanism involves syn 5-exo-dig cyclization, carbon monoxide insertion, and nucleophilic displacement by an alcohol. Desilylation occurred under the reaction conditions. The structure of a representative product, that is, methyl (Z)-2-[3-oxoisobenzofuran-1(3H)-ylidene]acetate, was confirmed by XRD analysis. (Figure presented.).