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.
The described system offers an ideal, user-friendly protocol for the chemoselective homogeneous hydrogenation of α,β-unsaturatedketones at room temperature using methanol as a liquid organic hydrogen carrier. Excellent yields were achieved with an in situ-prepared phosphine-free Cp*Ir(III)/bipyridonate complex. Chemoselective reduction with other reducible functionalities and late-stage functionalization
所描述的系统为使用甲醇作为液态有机氢载体在室温下对α、β-不饱和酮进行化学选择性均相氢化提供了一种理想的、用户友好的协议。使用原位制备的无膦Cp*Ir( III )/联吡啶络合物获得了优异的产率。还探索了具有其他可还原功能和后期功能化的化学选择性还原。
Chiral Bro̷nsted Acid-Catalyzed Asymmetric Friedel−Crafts Alkylation of Pyrroles with Nitroolefins
作者:Yi-Fei Sheng、Qing Gu、An-Jiang Zhang、Shu-Li You
DOI:10.1021/jo9013029
日期:2009.9.4
A highly efficient Friedel-Crafts reaction of pyrroles with nitroolefins by a chiral phosphoric acid was realized. With 5 mol % of catalyst, reactions conducted at rt afforded the 2-substituted or 2,5-disubstituted pyrroles in up to 94% ee for a wide range of substrates.
Asymmetric Friedel−Crafts Alkylation of Pyrroles with Nitroalkenes Using a Dinuclear Zinc Catalyst
作者:Barry M. Trost、Christoph Müller
DOI:10.1021/ja711080y
日期:2008.2.1
The catalytic enantioselective and atom economic Friedel-Crafts alkylation of pyrroles with nitroalkenes under mild reaction conditions using a dinuclear zinc catalyst is reported. The versatility of the reaction is demonstrated by the conversion of a number of differentially substituted nitroalkenes with differentially substituted pyrroles. Tandem addition reactions to form 2,5-disubstituted pyrroles are also demsonstrated. All pyrrole alkylations have been carried out without using N-protecting groups, which also enhances the efficiency by which substituted pyrroles may be synthesized. The reactions result in good yields and excellent enantioselectivities.
Addition of pyrroles to electron deficient olefins employing InCl3
Pyrroles undergo conjugate addition with electron deficient olefins in the presence of a catalytic amount of indium trichloride at ambient temperature to afford the corresponding Michael adducts in excellent yields with high selectivity without polymerisation. (C) 2001 Elsevier Science Ltd. All rights reserved.