One-Pot Synthesis of 2-Substituted Indoles and 7-Azaindoles via Sequential Alkynylation and Cyclization of 2-Iodo-N-mesylarylamines and Alkynes in the Presence of Cu2O.

Abstract

A one-pot process was developed to synthesize in moderate to high yield a series of 2-substituted indoles and 7-azaindoles starting from 2-iodo-N-mesylarylamines and terminal alkynes in the presence of Cu₂O in DMF at 90-120 °C. Without isolation of any intermediate, our optimized conditions enabled the introduction of ester, phenyl, hydroxymethyl, hydroxyethyl, N-Boc-aminomethyl, and methyl at the 2-postion of indoles and 7-azaindoles. The reaction tolerates a variety of substrates containing halogens, or acid- or base-sensitive functional groups without requiring a Pd catalyst, a ligand, or a base.