Ionic Liquid-Promoted Regiospecific Friedlander Annulation: Novel Synthesis of Quinolines and Fused Polycyclic Quinolines
作者:Sanjay S. Palimkar、Shapi A. Siddiqui、Thomas Daniel、Rajgopal. J. Lahoti、Kumar V. Srinivasan
DOI:10.1021/jo035153u
日期:2003.11.1
Several room-temperature ionic liquids (ILs) based on 1-butylimidazolium salts with varying anions were synthesized and evaluated for the preparation of biologically active substituted quinolines and fused polycyclic quinolines using the Friedlander heteroannulation reaction. On screening, 1-butylimidazolium tetrafluoroborate [Hbim]BF4 was found to be the best ionic liquid for the heteroannulation reaction
We have demonstrated the utilization of T3P, a mild and low toxic peptide coupling agent, as a promoter and water scavenger in the Friedlander annulation, and thus introduced a highly efficient catalytic process to access carbocyclic and heterocyclic fused quinolines under microwave irradiation or a conventional heating technique. The reaction conditions are sufficiently mild to tolerate the acid and base sensitive functional groups that can serve as levers for further extension of the quinoline products. (C) 2011 Elsevier Ltd. All rights reserved.