Cyclisation versus 1,1-Carboboration: Reactions of B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>with Propargyl Amides
作者:Rebecca L. Melen、Max M. Hansmann、Alan J. Lough、A. Stephen K. Hashmi、Douglas W. Stephan
DOI:10.1002/chem.201301899
日期:2013.9.2
A series of propargyl amides were prepared and their reactions with the Lewis acidic compound B(C6F5)3 were investigated. These reactions were shown to afford novel heterocycles under mild conditions. The reaction of a variety of N‐substituted propargyl amides with B(C6F5)3 led to an intramolecular oxo‐boration cyclisation reaction, which afforded the 5‐alkylidene‐4,5‐dihydrooxazolium borate species
制备了一系列炔丙基酰胺,并研究了它们与路易斯酸性化合物B(C 6 F 5)3的反应。这些反应显示在温和条件下提供新颖的杂环。各种N取代的炔丙基酰胺与B(C 6 F 5)3的反应导致了分子内的羰基硼化环化反应,提供了5亚烷基-4,5-二氢恶唑硼酸盐。炔丙基仲酰胺在B(C 6 F 5)3中得到恶唑介导的(催化)环化反应。在氮原子附近不稳定的特殊情况下,由于5-亚烷基-4,5-二氢恶唑鎓硼酸盐物种的空间位阻增加(1,3-烯丙基菌株),因此有利于1,1-碳链化。
Gold Catalysis: Products and Intermediates Obtained from N-Propargylcarboxamides Bearing Additional Substituents on Nitrogen
作者:A. Stephen K. Hashmi、Lise Molinari、Frank Rominger、Thomas Oeser
DOI:10.1002/ejoc.201100179
日期:2011.4
substrates with additional substituents on the nitrogen atom was investigated. Under aqueous conditions acyloxy-substituted allylammonium salts could selectively be obtained. Monitoring of the reactions by 1 H NMR spectroscopy indicated the presence of an intermediate. Then switching to anhydrous reaction conditions allowed the isolation and characterization of these intermediates, oxazoliniminium species
研究了几种炔丙酰胺底物与氮原子上的额外取代基的反应。在水性条件下,可以选择性地获得酰氧基取代的烯丙基铵盐。通过 1 H NMR 光谱监测反应表明存在中间体。然后切换到无水反应条件允许分离和表征这些中间体,恶唑啉鎓物种。在碱性条件下处理烯丙基铵盐导致酰基从氧原子转移到氮原子,这证明这些产物不是仅通过金催化的三键直接水合形成的,同时很好地解释了两个三键中只有一个的选择性一水合。
Visible‐Light Promoted Intramolecular
<i>para</i>
‐Cycloadditions on Simple Aromatics
We present the first synthesis of bridged bicycles through the dearomatization of sterically and electronically unbiased aryl fragments. The visible-light promoted method occurs at room temperature and has ample functional-group tolerance. The key to the difunctionalization of the aryl partner is the use of naphthalene as an additive, which stabilizes transient (bi)radicals through its extended π cloud