Highly Enantioselective Bromocyclization of Tryptamines and Its Application in the Synthesis of (−)-Chimonanthine
作者:Weiqing Xie、Guangde Jiang、Huan Liu、Jiadong Hu、Xixian Pan、Hui Zhang、Xiaolong Wan、Yisheng Lai、Dawei Ma
DOI:10.1002/anie.201306774
日期:2013.12.2
A shorter path: A highly enantioselective bromocyclization of tryptamine has been developed using an anionic chiral phase‐transfer catalyst. This method provides a direct approach for preparing chiral 3‐bromopyrroloindoline from tryptamine, which enables a four‐step enantioselective synthesis of (−)‐chimonanthine. PG=protecting group.
Stereocontrol: We have studied the enantioselective transannular aminohalogenation of unsaturated medium-sized cyclic benzosulfonamides by using both chiral Brønsted acid and phase-transfercatalysis. The mechanism of the reaction was also studied by using computational tools; we observed that the key step for stereocontrol involves the participation of an interconverting planar chiral conformer of
Enantioselective Halocyclization Using Reagents Tailored for Chiral Anion Phase-Transfer Catalysis
作者:Yi-Ming Wang、Jeffrey Wu、Christina Hoong、Vivek Rauniyar、F. Dean Toste
DOI:10.1021/ja305795x
日期:2012.8.8
A chiral anion phase-transfer system for enantioselective halogenation is described. Highly insoluble, ionic reagents were developed as electrophilic bromine and iodine sources, and application of this system to o-anilidostyrenes afforded halogenated 4H-3,1-benzoxazines with excellent yield and enantioselectivity.