Et2Zn-catalyzed intramolecular hydroamination of alkynyl sulfonamides and the related tandem cyclization/addition reaction.

Intramolecular hydroamination of alkynyl amides was effected by a catalytic amount of Et2Zn (20 mol %) to form indole derivatives, and a tandem cyclization/nucleophilic addition procedure involving reaction of the indole zinc salt intermediate with acid chlorides or halides was developed to provide an efficient approach to C3-substituted indole derivatives when an excess of Et2Zn (120 mol %) was used.