Control of 6-Exo and 7-Endo Cyclizations of Alkynylamides using Platinum and Bismuth Catalysts
作者:Anne-Lise Girard、Taro Enomoto、Shinsuke Yokouchi、Chihiro Tsukano、Yoshiji Takemoto
DOI:10.1002/asia.201100209
日期:2011.6.6
The rules of cyclization: Alkynylamides are regioselectively cycloisomerized into piperazin‐2‐one and 1,4‐diazepan‐2‐one derivatives by using catalytic amounts of appropriate metal catalysts. A 6‐exo‐dig addition proceeds in the presence of Bi(OTf)3, while the 7‐endo‐dig addition occurs with PtCl2 for the same substrate. (see scheme; Ns=o‐nitrobenzenesulfonyl, Ts=p‐toluenesulfonyl, Cbz=benzyloxycarbonyl
环化规则:使用催化量的适当金属催化剂,将炔属酰胺区域选择性地环异构化为哌嗪-2-酮和1,4-二氮杂-2-酮衍生物。在Bi(OTf)3存在的情况下进行6- exo- dig加成,而对于同一底物,PtCl 2进行7- endo- dig加成。(参见方案; Ns =邻硝基苯磺酰基,Ts =对甲苯磺酰基,Cbz =苄氧羰基,DCE =二氯乙烷)