Ring-Expansion Reaction of Isatins with Ethyl Diazoacetate Catalyzed by Dirhodium(II)/DBU Metal-Organic System: En Route to Viridicatin Alkaloids
作者:Roberta Paterna、Vânia André、M. Teresa Duarte、Luis F. Veiros、Nuno R. Candeias、Pedro M. P. Gois
DOI:10.1002/ejoc.201300796
日期:2013.10
present here the NHC-dirhodium(II)/DBU-catalyzed ring expansion reaction of isatins with ethyl diazoacetate. This new one-pot protocol yields the ethyl 3-hydroxy-2(1H)-oxoquinoline-4-carboxylate core, regioselectively and in good to excellent yields. A DFT mechanistic study indicates metallocarbene formation between the 3-hydroxyindole-diazo intermediate and the dirhodium(II) complex to be the rate-limiting
我们在此介绍了 NHC-二铑 (II)/DBU 催化的靛红与重氮乙酸乙酯的扩环反应。这种新的一锅法产生了 3-羟基-2(1H)-oxoquinoline-4-carboxylate 核心,区域选择性和良好的产率。DFT 机理研究表明,3-羟基吲哚-重氮中间体和二铑 (II) 络合物之间的金属卡宾形成是反应的限速步骤。合成的 3-羟基-2(1H)-氧喹啉-4-羧酸乙酯核心可以很容易地转化为绿色生物碱,通过微波辅助的 3-羟基-4-Suzuki-Miyaura 交叉偶联,产率高达 80%。溴喹啉-2(1H)-一种与芳基硼酸。