Base- and Copper-Catalysed Condensation of Primary Activated Nitro Compounds with Enolisable Compounds
作者:Elena Trogu、Luca Cecchi、Francesco De Sarlo、Luca Guideri、Fabio Ponticelli、Fabrizio Machetti
DOI:10.1002/ejoc.200900802
日期:2009.12
Primary nitro compounds have not been employed as nitrile oxide precursors in reactions with active methylene compounds because the reagents commonly used as dehydrating agents also react with these dipolarophiles. However, the CuII-catalysed cycloaddition/condensation procedure has been shown to be viable with these substrates, leading directly to the expected polyfunctional isoxazoles provided nitro
在与活性亚甲基化合物的反应中,初级硝基化合物尚未用作氧化腈前体,因为通常用作脱水剂的试剂也与这些亲偶极体反应。然而,CuII 催化的环加成/缩合程序已被证明对这些底物是可行的,如果使用具有增强酸度(“活化”)的硝基化合物,则直接导致预期的多官能异恶唑。在不添加亲偶极体的情况下,这些硝基化合物会发生自缩合反应生成相应的呋喃。然而,与 3,4-二苯甲酰呋喃一样,苯甲酰硝基甲烷主要产生异构体 3-苯甲酰-4-硝基-5-苯基异恶唑,其结构已通过结晶分析证实。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)