Tandem Cyclopropane Ring-Opening/Conia-ene Reactions of 2-Alkynyl Indoles: A [3+3] Annulative Route to Tetrahydrocarbazoles

A Zn(NTf2)(2) catalyzed tandem reaction consisting of a nucelophilic ring opening of 1,1-cyclopropanediesters by 2-alkynyl indoles followed by a Conia-ene ring closure results in the efficient one-step synthesis of tetrahydrocarbazoles. The adducts may be further elaborated to carbazoles.