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Synthesis of β- and γ-Carbolines by the Palladium/Copper-Catalyzed Coupling and Cyclization of Terminal Acetylenes
journal contribution
posted on 2002-08-30, 00:00 authored by Haiming Zhang, Richard C. LarockA variety of 3-substituted β- and γ-carbolines have been synthesized from N-substituted 3-iodoindole-2-carboxaldehydes and 2-bromoindole-3-carboxaldehydes, respectively. The coupling of these
aldehydes with various terminal acetylenes with PdCl2(PPh3)2/CuI as the catalyst readily affords
the corresponding alkynylindole carboxaldehydes, which have subsequently been converted to the
corresponding tert-butylimines and cyclized to β- and γ-carbolines by either copper-catalyzed or
thermal processes.