A Comparative Mechanistic Study of Cu-Catalyzed Oxidative Coupling Reactions with N-Phenyltetrahydroisoquinoline
摘要:
A comparative mechanistic study of Cu-catalyzed oxidative coupling reactions of N-phenyltetrahydroisoquinoline with different nucleophiles was conducted. Two previously reported combinations of catalyst and oxidant were studied, CuCl2 center dot 2H(2)O/O-2 and CuBr/tert-butyl hydroperoxide (TBHP). On the basis of a synthetic study with different nucleophiles, the electrophilicity of the intermediate iminium ion was estimated and differences between the two methods were revealed. The key intermediate in the aerobic method is shown to be an iminium ion, formed through oxidation by copper(II), which can react with any nudeophile of sufficient reactivity. The role of oxygen is the reoxidation of the reduced catalyst. In the CuBr/TBHP system, an alpha-amino peroxide is proposed as a true intermediate within the catalytic cycle, formed from the amine and TBHP by a Cu-catalyzed radical reaction pathway and acting as a precursor to the iminium ion intermediate.
Efficient Stereoselective Synthesis of Nitrocyclopropanes by the Oxidative Cyclization of Michael Adducts of Nitroolefins with Activated Methylene Compounds
作者:Renhua Fan、Yang Ye、Weixun Li、Lingfei Wang
DOI:10.1002/adsc.200800452
日期:2008.11.3
An efficientoxidative cyclopropanation of the Michaeladducts of nitroolefins with activatedmethylenecompounds by the combination of iodobenzene diacetate and tetrabutylammonium iodide is reported. Highly functionalized nitrocyclopropanes are synthesized in moderate to good yields via the Michael addition and cyclopropanation with high diastereoselectivity and enantioselectivity under mild conditions
An efficient strategy for the mechanosynthesis of gamma-nitro dicarbonyl esters has been developed. A CaCl2-catalyzed Michael reaction, conducted at room temperature, afforded nitroalkenes from malonates in a short reaction time and in high yields. In most cases, polymerized side-reactions are eliminated or minimized. (C) 2013 Elsevier Ltd. All rights reserved.
Boron Trifluoride Mediated Ring-Opening Reactions of <i>trans</i>-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates. Synthesis of Aroylmethylidene Malonates as Potential Building Blocks for Heterocycles
作者:Thangavel Selvi、Kannupal Srinivasan
DOI:10.1021/jo402848v
日期:2014.4.18
trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates, upon treatment with BF3 center dot OEt2, undergo ring-opening rearrangement and the Nef reaction to give aroylmethylidene malonates. The products are found to be potential precursors for heterocycles, such as imidazoles, quinoxalines, and benzo[1,4]thiazines.
A Comparative Mechanistic Study of Cu-Catalyzed Oxidative Coupling Reactions with <i>N</i>-Phenyltetrahydroisoquinoline
作者:Esther Boess、Corinna Schmitz、Martin Klussmann
DOI:10.1021/ja211697s
日期:2012.3.21
A comparative mechanistic study of Cu-catalyzed oxidative coupling reactions of N-phenyltetrahydroisoquinoline with different nucleophiles was conducted. Two previously reported combinations of catalyst and oxidant were studied, CuCl2 center dot 2H(2)O/O-2 and CuBr/tert-butyl hydroperoxide (TBHP). On the basis of a synthetic study with different nucleophiles, the electrophilicity of the intermediate iminium ion was estimated and differences between the two methods were revealed. The key intermediate in the aerobic method is shown to be an iminium ion, formed through oxidation by copper(II), which can react with any nudeophile of sufficient reactivity. The role of oxygen is the reoxidation of the reduced catalyst. In the CuBr/TBHP system, an alpha-amino peroxide is proposed as a true intermediate within the catalytic cycle, formed from the amine and TBHP by a Cu-catalyzed radical reaction pathway and acting as a precursor to the iminium ion intermediate.
Iodobenzene-Catalyzed Oxidative Cyclization for the Synthesis of Highly Functionalized Cyclopropanes
作者:Yang Li、Hao Guo、Renhua Fan
DOI:10.1055/s-0039-1690809
日期:2020.3
iodobenzene-catalyzed oxidative cyclization of Michael adducts of activated methylene compounds with nitroolefins or chalcones is developed. mCPBA is used as oxidant together with Bu4NI for the generation of a highly reactive iodine(III) species to mediate the cyclopropanation via a ligand exchange and reductive elimination process. A range of highly functionalized cyclopropanes are synthesized with