t -BuOLi promoted regioselective N -thiolation of indoles with N -arylthio phthalimide.

The selective N -thiolation of indole substrates poses a challenge due to their diminished nucleophilicity at nitrogen. Herein, we present a novel method for the thiolation of the NH group in indole derivatives by using N -arylthio phthalimide as the sulfur source, t -BuOLi as the base and MeCN as the solvent. The process was successfully conducted under transition metal catalyst-free and room temperature conditions with a high product yield and a short reaction time. The developed protocol exhibited excellent regioselectivity and broad substrate tolerance in the preparation of N -thioindoles with diverse functional groups.