One-Pot Synthesis of Indoles and N-Fused Indoles from Nitriles

Abstract

Reported is a moderately efficient synthesis of indoles 3 and N-fused indoles 5 by the reaction of nitriles 1 and 4 with ethyl (2-bromophenyl)-α-bromoacetate 2. The synthesis involves a two-step, one-pot sequence in which nitriles 1 or 4 initially undergo a Blaise reaction with a Reformatsky reagent generated in situ from 2 and zinc metal, followed by intramolecular C-N coupling to form the indole derivatives 3 and 5. Both aliphatic and aromatic nitriles are suitable for the reaction and in case of the latter, both EDG and EWG are tolerated.