Photo-driven synthesis of N-sulfonylformamidines: a catalyst- and sensitiser-free approach

Amidines, a prominent class of nitrogen-containing organic compounds, exhibit distinctive biological activities and are widely incorporated into pharmaceutically relevant molecules. Herein, we report an efficient synthesis of N-sulfonylamidines from N,N-dibromoarylsulfonamides under simple LED irradiation, without the need for photocatalysts or photosensitizers. Exposure of N,N-dibromoarylsulfonamides to readily available white LEDs promotes homolytic cleavage of the N-Br bonds, generating both the key nitrene intermediate and bromine radicals. The in situ-formed nitrene subsequently reacts with formamides to produce an oxaziridine intermediate, which undergoes further transformation under the influence of bromine radicals to deliver the desired sulfonylimination products. Notably, the transformation proceeds under exceptionally mild conditions and within a short reaction time. Combined with its broad substrate scope, high functional group tolerance, operational simplicity, and enhanced chemical sustainability, this protocol offers considerable potential for future synthetic and pharmaceutical applications.