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

The first example of the oxidative carbonylation of 2‐ethynylbenzoic acid derivatives, leading to alkyl ( Z )‐2‐[3‐oxoisobenzofuran‐1‐(3 H )‐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(3 H )‐ylidene]acetate, was confirmed by XRD analysis.