An Efficient [2+2+1] Synthesis of 2,5-Disubstituted Oxazoles via Gold-Catalyzed Intermolecular Alkyne Oxidation
An Efficient [2+2+1] Synthesis of 2,5-Disubstituted Oxazoles via Gold-Catalyzed Intermolecular Alkyne Oxidation
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DOI：
10.1021/ja2029188
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发表时间：
2011-06-08
影响因子：
15
通讯作者：
Zhang, Liming
中科院分区：
文献类型：
--
作者：
He, Weimin;Li, Chaoqun;Zhang, Liming
第一个有效的分子间反应产生的金卡宾中间体通过金催化的炔氧化已实现使用腈作为反应伙伴和反应溶剂，提供了一个普遍有效的合成2，5-二取代恶唑具有广泛的底物范围。整个反应是末端炔、腈和来自氧化剂的氧原子的[2 + 2 + 1]成环。反应条件非常温和，并且很容易耐受一系列官能团。对于复杂和/或昂贵的腈，在不存在任何溶剂和仅使用1摩尔% BrettPhos-AuNTf 2作为催化剂的情况下，仅3当量就足以实现可用的产率。
The first efficient intermolecular 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 are exceptionally mild, and a range of functional groups are easily tolerated. With complex and/or expensive nitriles, only 3 equiv could be sufficient to achieve serviceable yields in the absence of any solvent and using only 1 mol % BrettPhos-AuNTf2 as the catalyst.