Synthesis of Sulfonated Benzo[d][1,3]oxazines by Merging Photoredox Catalysis and Insertion of Sulfur Dioxide

A photocatalytic reaction of N-(2-vinylphenyl)amides, DABCO(SO2)(2) and arenediazonium tetrafluoroborates for the synthesis of 4-((arylsulfonyl)methyl)-4H-benzo[d][1,3]oxazines under mild conditions is reported. This synthetic approach is enabled by merging photoredox catalysis and insertion of sulfur dioxide via a radical process. The specific role of photoredox catalysis in this transformation is supported by mechanistic investigations and theoretical calculations.