An Efficient [2 + 2 + 1] Synthesis of 2,5-Disubstituted Oxazoles via Gold-Catalyzed Intermolecular Alkyne Oxidation
作者:Weimin He、Chaoqun Li、Liming Zhang
DOI:10.1021/ja2029188
日期:2011.6.8
reaction of gold carbene intermediates generated via gold-catalyzed alkyne oxidation has been realized using nitriles as both the reacting partner and the reaction solvent, offering a generally efficient synthesis of 2,5-disubstituted oxazoles with broad substrate scope. The overall reaction is a [2 + 2 + 1] annulation of a terminal alkyne, a nitrile, and an oxygen atom from an oxidant. The reaction conditions
通过金催化炔氧化生成的金卡宾中间体的第一个有效分子间反应已经实现,使用腈作为反应伙伴和反应溶剂,提供了具有广泛底物范围的 2,5-二取代恶唑的普遍有效合成。整个反应是末端炔烃、腈和来自氧化剂的氧原子的 [2 + 2 + 1] 环化。反应条件异常温和,并且容易耐受一系列官能团。对于复杂和/或昂贵的腈,在没有任何溶剂且仅使用 1 mol% BrettPhosAuNTf(2) 作为催化剂的情况下,仅 3 equiv 就足以实现可用的产率。