Photochemistry of N ‐Substituted, N ′‐Tosyl Diphenyl Sulfondiimines

ABSTRACT

Sulfondiimines are an emerging sulfur(VI) functional group with increasing use in synthesis and medicinal chemistry, yet their photochemical behavior has remained largely unexplored. In this work, the photochemistry of a series of six N ‐substituted, N ′‐tosyl diphenyl sulfondiimines was analyzed. Upon direct UV irradiation, five derivatives underwent efficient photodenitrenation in a consistent, stepwise order: extrusion of the N ‐substituent nitrene followed by release of the N ‐tosyl nitrene from the corresponding sulfilimine. This sequential nitrene release is a rare behavior that has not been observed previously. Quantum yield measurements reveal strong substituent dependence, with aryl substituents exhibiting substantially higher photochemical efficiency (0.22–0.31) than alkyl substituents (~0.1), whereas the NH‐substituted compound remained photoinert under our conditions. Product profiles and trapping experiments support the S–N cleavage in sulfondiimines to release the nitrene through a singlet manifold. Photosensitization experiments revealed the triplet manifold is dissociative as well, albeit with a greater number of side reactions. Quantum chemical calculations further supported this mechanism by relating the release order to relative S–N bond strengths and identifying a dissociative excited state along the S–N coordinate.