Palladium-catalyzed three-component cascade arylthiolation with aryldiazonium salts as S-arylation sources

A novel and efficient palladium-catalyzed three-component cascade cyclization/arylthiolation for the assembly of diverse 3-sulfenylindoles and 3-sulfenylbenzofurans derivatives from 2-alkynylamines and 2-alkynylphenols, aryldiazonium salts, and Na2S2O3 under aerobic conditions with PEG-200 as an environmentally benign medium has been developed. The current study features exceptional functional group tolerance, without additional ligand or oxidant or silver salt, eco-friendly, and mild reaction conditions. Ionic liquids [C2OHmim]Cl as the environmental friendliness additive plays crucial roles in this protocol. Notably, this procedure represents the first example for the use of aryldiazonium salts as the direct S-arylation sources in this type chemical transformation.