Three‐Component C–H Bond Sulfonylation of Imidazoheterocycles by Visible‐Light Organophotoredox Catalysis

The first entirely visible‐light photoredox catalyzed sulfonylation of imidazoheterocycles has been developed. This transformation demonstrates an efficient C–H functionalization for the straightforward synthesis of novel C‐3 sulfonylated imidazoheterocycles from various imidazopyridines and diaryliodonium salts with different electronic and steric properties and easy to handle DABCO‐bis(sulfur dioxide). The reaction proceeds in moderate to good yields under mild conditions at room temperature using the inexpensive organophotocatalyst EosinY·Na2 and shows a high functional group tolerance (37 examples). The first examples of visible‐light induced direct sulfur dioxide insertion on imidazoheterocycles have been developed using an organic photoredox catalyst at room temperature and DABCO·(SO2)2. The formation of 2 new C–S bonds, without further pre‐functionalization, in metal‐free and mild conditions render this three‐component approach sustainable and green and led to novel and valuable C‐3 sulfonylated imidazoheterocycles in moderate to good yields.