Rhodium(II)-Catalyzed Hinsberg Dearomatization Using Trimethylsilyldiazomethane

Rhodium­(II) catalyzes carbene transfer from trimethylsilyldiazomethane to arylmethyl thioethers, generating sulfonium ylides that undergo [2,3]-sigmatropic rearrangement, punching quaternary centers into aromatic rings. The reaction works well with naphthalene, indole, and benzofuran ring systems, but the reaction is unsuccessful with the monocyclic benzene homologue. For aryl thioethers, Rh2(OAc)4 gives good results. For alkyl thioethers, the yields improve with Rh2(cap)4. Surprisingly, thioesters and thiocarbamates are also competent substrates for the reaction.