C−C Bond‐Forming Strategy by Manganese‐Catalyzed Oxidative Ring‐Opening Cyanation and Ethynylation of Cyclobutanol Derivatives

A novel C−C bond‐forming strategy employing manganese‐catalyzed ring‐opening of cyclobutanol substrates, followed by cyanation or ethynylation, is described. A cyano C1 unit and ethynyl C2 unit are regiospecifically introduced to the γ‐position of ketones at room temperature, providing a mild yet powerful method for production of elusive aliphatic nitriles and alkynes. All transformations described are based on a common sequence: 1) oxidative ring‐opening of cyclobutanol substrates by C−C bond cleavage; 2) radical addition to triple bonds bearing an arylsulfonyl group; and 3) radical‐mediated C−S bond cleavage.