N‐Heterocyclic Carbene‐Catalyzed Formal [6+2] Annulation Reaction via Cross‐Conjugated Aza‐Trienolate Intermediates
作者:Kuruva Balanna、Krishnaprasad Madica、Subrata Mukherjee、Arghya Ghosh、Thomas Poisson、Tatiana Besset、Garima Jindal、Akkattu T. Biju
DOI:10.1002/chem.201905177
日期:2020.1.16
The diverse reactivity of N-heterocyclic carbenes (NHCs) in organocatalysis is due to the possibility of different modes of action. Although NHC-bound enolates and dienolates are known, the related NHC-bound cross-conjugated aza-trienolates remain elusive. Herein, we demonstrate the NHC-catalyzed formal [6+2] annulation of nitrogen-containing heterocyclic aldehydes with α,α,α-trifluoroacetophenones
Synthesis of β- and γ-Carbolines by the Palladium/Copper-Catalyzed Coupling and Cyclization of Terminal Acetylenes
作者:Haiming Zhang、Richard C. Larock
DOI:10.1021/jo0258857
日期:2002.10.1
A variety of 3-substituted beta- and gamma-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 beta- and gamma-carbolines by either copper-catalyzed or thermal processes.