Palladium-Catalyzed Carbene Migratory Insertion Using Conjugated Ene–Yne–Ketones as Carbene Precursors
作者:Ying Xia、Shuanglin Qu、Qing Xiao、Zhi-Xiang Wang、Peiyuan Qu、Li Chen、Zhen Liu、Leiming Tian、Zhongxing Huang、Yan Zhang、Jianbo Wang
DOI:10.1021/ja4058844
日期:2013.9.11
Palladium-catalyzed cross-coupling reactions between benzyl, aryl, or allyl bromides and conjugated ene-yne-ketones lead to the formation of 2-alkenyl-substituted furans. This novel coupling reaction involves oxidative addition, alkyne activation-cyclization, palladium carbene migratory insertion, β-hydride elimination, and catalyst regeneration. Palladium (2-furyl)carbene is proposed as the key intermediate
苄基、芳基或烯丙基溴化物与共轭烯-炔-酮之间的钯催化交叉偶联反应导致形成 2-烯基取代的呋喃。这种新型偶联反应涉及氧化加成、炔烃活化-环化、钯卡宾迁移插入、β-氢化物消除和催化剂再生。钯(2-呋喃基)卡宾被提议作为关键中间体,这得到了 DFT 计算的支持。关键中间体的钯卡宾特性通过三个方面进行验证,包括键长、Wiberg 键序指数和分子轨道,与稳定的钯卡宾物种的报道进行比较。计算研究还表明,限速步骤是烯-炔-酮环化,这导致钯(2-呋喃基)卡宾的形成,