Enantioselective BINOL-Phosphoric Acid Catalyzed Pictet−Spengler Reactions of <i>N</i>-Benzyltryptamine
作者:Nishant V. Sewgobind、Martin J. Wanner、Steen Ingemann、René de Gelder、Jan H. van Maarseveen、Henk Hiemstra
DOI:10.1021/jo8010478
日期:2008.8.1
[GRAPHICS]Optically active tetrahydro-beta-carbolines were synthesized via an (R)-BINOL-phosphoric acid-catalyzed asynunetric Pictet-Spengler reaction of N-benzyltryptamine with a series of aromatic and aliphatic aldehydes. The tetrahydro-beta-carbolines were obtained in yields ranging from 77% to 97% and with ee values up to 87%. The triphenylsilyl-substituted BINOL-phosphoric acid proved to be the catalyst of choice for the reaction with aromatic aldehydes. For the aliphatic aldehydes, 3,5 -bistrifluoromethylphenyL-substituted BINOL-phosphoric acid was identified as the best catalyst.