Gold Catalysis: Mild Conditions for the Synthesis of Oxazoles from <i>N</i>-Propargylcarboxamides and Mechanistic Aspects
作者:A. Stephen K. Hashmi、Jan P. Weyrauch、Wolfgang Frey、Jan W. Bats
DOI:10.1021/ol0480067
日期:2004.11.1
2,5-Disubstituted oxazoles are synthesized from the corresponding propargylcarboxamides under mild reaction conditions via homogeneous catalysis by AuCl(3). While monitoring the conversion via (1)H NMR spectroscopy, an intermediate 5-methylene-4,5-dihydrooxazole can be observed and accumulated up to 95%, being the first direct and catalytic preparative access to such alkylidene oxazolines. The intermediate
2,5-二取代的恶唑是由相应的炔丙基羧酰胺在温和的反应条件下通过AuCl(3)的均相催化合成的。在通过(1)H NMR光谱监测转化率的同时,可以观察到中间体5-亚甲基-4,5-二氢恶唑并累积至多95%,这是对此类亚烷基恶唑啉的直接直接和催化制备途径。中间体已被充分表征,可以在-25摄氏度下捕获数周。氘代实验显示了反应的两个第一步的立体定向模式。