Geminal Difunctionalization of Ketones via C─S Bond Insertion of Photogenerated Donor-Donor Diazo Compounds.

Geminal difunctionalization of carbonyl-derived building blocks represents a versatile strategy for the rapid generation of sp3-rich molecular architectures. In this context, diazo compounds provide a powerful platform for installing two distinct functional groups, yet the reaction space for carbonyl-derived donor-donor diazo systems remains underdeveloped. Here, we report a metal-free migratory insertion of diazo compounds into C─S bonds of sulfonyl cyanides, enabling the simultaneous installation of sulfone and nitrile functionalities at a single carbon center. Key to this transformation is the in situ generation of highly reactive diazo intermediates via photochemical decomposition of bench-stable oxadiazolines derived from ketones. This substantially expands the accessible coupling partner space, previously limited to aldehydes or boronic acids. The reaction exhibits broad functional group, water, and air tolerance, delivers high yields, and provides excellent diastereoselectivity in constrained cyclic systems. Compatibility with both batch and continuous-flow processing, as well as its application to a realistic medicinal chemistry combinatorial library synthesis, highlights the practical utility of the method.