Synthesis of indolines via a SmI promoted domino nitro reduction-intramolecular aza-Michael reaction.

Abstract

A simple and straightforward synthesis of substituted indolines based on a domino nitro reduction intramolec-ular aza-Michael reaction is described. The reaction employs Samarium diiodide under mild conditions for theaddition of dibromoacetic acid to substituted 2-(2-nitrophenyl) acetaldehyde derivatives and their subsequent cycli-zation upon nitro group reduction to provide corresponding indoline heterocycles in good yields. This “one pot”strategy also permitted the expeditious synthesis of a 1,2,3,4-tetrahydroquinoline, whereas the seven-membered2,3,4,5-tetrahydrobenzoazepines compounds were not formed under these reaction conditions.