Homologation of Alkenyl Carbonyls via a Cyclopropanation/Light‐Mediated Selective C−C Cleavage Strategy

Abstract We report herein our studies on the direct photoactivation of carbonyl cyclopropanes to give biradical intermediates, leading to selective cleavage of the more substituted carbon‐carbon bond. Depending on the substrate structure, extended alkenes were isolated or directly reacted in a photo‐Nazarov process to give bicyclic products. Based on these results, a unified reductive ring‐opening reaction was developed by using diphenyl disulfide as a hydrogen atom transfer (HAT) reagent. By performing a sequential cyclopropanation/selective ring opening reaction, we achieved a CH 2 insertion into the α,β bond of both acyclic and cyclic unsaturated carbonyl compounds. Our protocol provides a further tool for the modification of the carbon framework of organic compounds, complementing the recent progress in “skeletal editing”.