Synthesis of tetrahydro-5-azaindoles and 5-azaindoles using Pictet–Spengler reaction—appreciable difference in products using different acid catalysts
摘要:
Pictet-Spengler condensation of 2-(aryl)-2-(1H-pyrrol-2-yl)ethanamines using conventional acid catalysts like TMSCl or TFA resulted in the formation of substituted 5-azaindoles involving a tandem one pot four steps reaction sequence. By contrast use of glacial acetic acid furnished the targeted tetrahydro-5-azaindoles in diastereoselective manner. These were readily dehydrogenated to 5-azaindoles. (C) 2010 Elsevier Ltd. All rights reserved.
generate indolyl nitroalkane 5 and pyrrolyl nitroalkane 7 in high yields using β-nitrostyrene and indole/pyrrole at room temperature in the presence of catalytic amount of iodine is reported. The short reaction times and high yields of product are noteworthy. Molecular iodine promoted Michaeladdition is operationally simple and efficient method compared to the known Lewis acids or rare earth metal
Enantioselective and Regioselective Friedel-Crafts Alkylation of Pyrroles with Nitroalkenes Catalyzed by a Tridentate Schiff Base-Copper Complex
作者:Fengfeng Guo、Dalu Chang、Guoyin Lai、Tao Zhu、Shunshun Xiong、Sujing Wang、Zhiyong Wang
DOI:10.1002/chem.201102206
日期:2011.9.26
On a (pyr)role: A mild and highly efficientcatalytic system has been developed for the asymmetric Friedel–Crafts alkylation of pyrroles with nitroalkenes (see scheme). High yields, and excellent enantioselectivities and regioselectivities were obtained for a broad range of substrates. The synthetic utility of this methodology and mechanisticstudies involving a novel, negative, nonlinear effect are
Microwave-Assisted Addition of Pyrroles to Electron-Deficient Olefins: A Rapid Entry to<i>C</i>-Alkyl Pyrroles
作者:Zhuang-Ping Zhan、Wen-Zhen Yang、Rui-Feng Yang
DOI:10.1055/s-2005-872688
日期:——
A general procedure for the Michaeladdition of pyrroles with electron-deficientolefins using silica gel supported reagent under microwave irradiation, has been developed. This new method is fast, efficient, environmentally benign and solvent-free. A catalytic amount of BiCl 3 is employed for moderately bulk electron-deficientolefins.
Montmorillonite K10 was found to catalyze the Michaeladdition of indoles or pyrrole with nitroalkenes efficientlyunder solventless condition. The short reaction time, simple workup, and excellent yields were noteworthy. The green catalyst could be reused for three runs without considerable variation in yield.
Silica Gel, an Effective Catalyst for the Reaction of Electron-Deficient Nitro-Olefins with Nitrogen Heterocycles
作者:Abdullah M. A. Shumaila、Radhika S. Kusurkar
DOI:10.1080/00397910903340694
日期:2010.8.31
The reaction of electron-deficientolefins with nitrogen heterocycles such as pyrrole and indole was examined in the presence of silica gel at room temperature under stirring at solvent-free conditions. It was found that silica gel is an effective catalyst for this conjugate addition. This work resulted in the formation of monosubstituted pyrroles selectively as a major product except in a few cases