Transition‐Metal‐Free or Visible‐Light Catalyzed Selective C–C Bond Cleavage of Cyclobutanone Oxime Derivatives

The cyanoalkyl group, as a key functional motif, is widely distributed in pharmacologically active molecules, natural products, and functional materials, and its efficient incorporation is of great significance for modern synthetic chemistry. Traditional cyanoalkylation methods usually rely on toxic cyanide sources, high temperatures, or transition‐metal catalysis, facing challenges such as harsh conditions and insufficient selectivity. In recent years, cyclobutanone oxime esters have emerged as ideal precursors for cyanoalkylation reactions due to their inherent ring strain and reactivity. Through visible‐light or transition‐metal‐free catalytic systems, they provide innovative pathways for the green and efficient construction of cyanoalkyl groups. This review systematically summarizes recent key advances in this field, covering C–C bond cleavage reactions of cyclobutanone oxime esters under visible‐light and transition‐metal‐free catalysis, with a focus on their applications in cyanoalkylation, cyanoalkylsulfonylation, cyanoalkylcarbonylation, and multicomponent cyclization transformations. Additionally, a detailed discussion will be provided on the substrate generality, mechanisms, and applications of these reactions, concluding with an outlook on the future development and current limitations of this research area.