Geminal Difunctionalization of Ketones via C–S Bond Insertion of Photogenerated Donor–Donor Diazo Compounds

The direct geminal difunctionalization of ketone-derived diazo compounds offers a powerful platform for generating sp³-rich molecular architectures, yet remains largely underdeveloped, particularly in the context of unstabilized donor–donor systems. Migratory insertion reactions of unstabilized diazo compounds have emerged as a metal-free, efficient, and versatile approach for constructing highly substituted carbon centers, attracting considerable interest in recent decades. However, the range of compatible coupling partners has remained confined to aldehydes and boronic acids. To expand the available chemical space of these transformations, we report a metal-free migratory insertion of diazo compounds into carbon–sulfur bonds of sulfonyl cyanides, enabling the simultaneous installation of sulfone and nitrile functionalities at a single carbon center. In this strategy, inherently unstable diazo intermediates are generated in situ via photochemical decomposition of bench-stable oxadiazolines, which are readily synthesized from the corresponding ketones. The reaction exhibits broad functional group, water, and air tolerance, and affords high yields with excellent diastereoselectivity in constrained cyclic systems. Furthermore, the methodology is compatible with both batch and continuous flow processes and has been successfully applied within a realistic med chem scenario to the synthesis of a combinatorial matrix library.