Photoreaction of Nitrobenzene Derivatives with Alkyl Thiols Giving Sulfonamides and Derivatives

Here, we serendipitously found that photoirradiation of nitrobenzene derivatives with alkyl thiols produced sulfonamides in low yields without the addition of other reagents. We proposed a new photoreaction mechanism, in which the photo-excited nitrobenzene biradical abstracts a hydrogen atom from H-S, the resultant thiyl radical undergoes the coupling with the nitrogen atom in the nitro group, and the two oxygen atoms in the nitro group are transferred onto the sulfur atom. The photoreaction by-produced p-sulfanyl, aniline, and o-sulfonyl derivatives presumably through S(RN)1 mechanism from the p-substituted nitrobenzene, photo-desulfonylation, and photo-Fries rearrangement from the sulfonamide, respectively. Discovery of this photoreaction will expand the scope of the chemistry of nitro and thiol compounds, since the sulfonamides are expected to find extensive applications.