An Efficient [2 + 2 + 1] Synthesis of 2,5-Disubstituted Oxazoles via Gold-Catalyzed Intermolecular Alkyne Oxidation
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- 作者：Weimin He ; Chaoqun Li ; Liming Zhang
- 刊名：Journal of the American Chemical Society
- 出版年：2011
- 出版时间：June 8, 2011
- 年：2011
- 卷：133
- 期：22
- 页码：8482-8485
- 全文大小：793K
- 年卷期：v.133,no.22(June 8, 2011)
- ISSN：1520-5126
文摘
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 % BrettPhosAuNTf2 as the catalyst.