Modular esterification of unstrained carbonyls through palladium-catalyzed alkyne bridging C-C bond activation

The insertion of an oxygen atom into carbon-carbon (C-C) σ-bonds of readily available ketones to form esters represents a fundamental transformation known as Baeyer-Villiger (BV) oxidation. While this classical reaction serves as a cornerstone in organic synthesis, its scope remains limited to single oxygen-atom insertion into ketone substrates. We herein report a versatile catalytic protocol that enables the insertion of alkynyl phenol analogues into unstrained C-C σ-bonds of diverse carbonyl compounds, including ketones, esters, and amides. This method provides modular access to an array of structurally varied products ranging from linear esters to medium- and macrocyclic lactones. This methodology displays broad substrate scope, excellent functional group tolerance, direct applicability to bioactive molecule modification with effective transfer of axial chirality. An in-depth computational study provides insights into the reaction mechanism. While Baeyer-Villiger oxidation reaction has served as a cornerstone in organic synthesis, its scope remains limited to single oxygen-atom insertion into ketone substrates. Here, the authors report a versatile protocol that enables the insertion of alkynyl phenol analogues into unstrained C-C σ-bonds of diverse carbonyl compounds, including ketones, esters, and amides.