An unexpected rearrangement-hydration reaction sequence of 2H-chromenes to dihydrochalcones under catalysis of HAuCl4
摘要:
2-Aryl-2H-chromenes in aqueous DCM medium under catalysis of HAuCl4 are converted into 3-(2-hydroxyaryl)-1-arylpropan-1-ones through hydration-rearrangement reaction sequence in very good yield. The key step probably involves the [1,5] hydride shift followed by the hydrolysis under the reaction condition. The notable advantages of this method are operational simplicity and ease of isolation of products and also provide a pathway to convert the chalcone into DHCs with the transposition of carbonyl group. (C) 2012 Elsevier Ltd. All rights reserved.
Palladium-catalyzed coupling of N-tosylhydrazones and β-bromostyrene derivatives: new approach to 2H-chromenes
作者:Yamu Xia、Ying Xia、Yan Zhang、Jianbo Wang
DOI:10.1039/c4ob01979b
日期:——
structural motif that exists in natural products and non-natural compounds possessing interesting biological activities. In this investigation, a highly efficient approach toward 2H-chromenes has been developed based on palladium-catalyzedcoupling of N-tosylhydrazones and β-bromostyrenes. The mechanism of this reaction is proposed that involves the formation of vinyl palladium by carbene migratory insertion
2 H -Chromene是存在于天然产物和具有有趣生物活性的非天然化合物中的重要结构基序。在这项研究中,基于钯催化的N-甲苯磺酰hydr和β-溴苯乙烯的偶联,已经开发出一种高效的2 H-苯甲基苯胺的方法。提出了该反应的机理,该机理涉及通过卡宾迁移插入和分子内亲核取代形成乙烯基钯。
Transition-Metal-Free Cross-Coupling of Indium Organometallics with Chromene and Isochroman Acetals Mediated by BF<sub>3</sub>·OEt<sub>2</sub>
作者:José M. Gil-Negrete、José Pérez Sestelo、Luis A. Sarandeses
DOI:10.1021/acs.orglett.6b02058
日期:2016.9.2
coupling of triorganoindiumreagents with benzopyranyl acetals mediated by a Lewis acid has been developed. The reaction of R3In with chromene and isochroman acetals in the presence of BF3·OEt2 afforded 2-substituted chromenes and 1-substituted isochromans, respectively, in good yields. The reactions proceed with a variety of triorganoindiumreagents (aryl, heteroaryl, alkynyl, alkenyl, alkyl) using