Solid-phase synthesis of 2-aryl-3-alkylamino-1H-indoles from 2-nitro-N-(2-oxo-2-arylethyl)benzenesulfonamides via base-mediated C-arylation.

Polymer-supported 2-nitro-N-(2-oxo-2-arylethyl)benzenesulfonamides, prepared from resin-bound amines by sulfonylation with 2-nitrobenzenesulfonyl chlorides followed by alkylation with α-bromoacetophenones, represent advanced intermediates for the synthesis of different nitrogenous heterocycles. We report their application for the synthesis of 2-aryl-3-alkylamino-1H-indoles via base-mediated C-arylation reactions followed by the reduction of the C-arylated intermediates. Linear precursors for C-arylation were prepared on solid-phase support from simple, commercially available building blocks. The effects of different substituents on the amino and aryl groups were addressed.