Reductive tert-Butylation of Anils by tert-Butylmercury Halides

摘要

tert-Butyl radicals add to the carbon atom of benzylideneanilines to form anilino radicals, which are protonated in the presence of PTSA or NH_4~+ in Me_2SO. Reduction of the resulting aniline radical cations occurs readily by the ate complex, t-BuHgI_2~-. In the absence of a proton donor, t-BuHgI will also transfer a hydrogen atom to the anilino radical to give the reductive alkylation product. Protonation can promote a free radical chain process involving electron transfer by substrate activation and/or by increasing the electron affinity of the intermediate radicals. Since the adduct radicals formed from benzylideneanilines are more easily protonated than the parent Schiff bases, PTSA but not NH_4~+ demonstrates substrate activation, although both proton donors promote the free radical reaction.