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
Facile, Selective, and Regiocontrolled Synthesis of Oxazolines and Oxazoles Mediated by ZnI<sub>2</sub> and FeCl<sub>3</sub>
作者:Gopal Chandru Senadi、Wan-Ping Hu、Jia-Shing Hsiao、Jaya Kishore Vandavasi、Chung-Yu Chen、Jeh-Jeng Wang
DOI:10.1021/ol301980g
日期:2012.9.7
An expedient method for a direct approach to the selective and regiocontrolled synthesis of 2-oxazolines and 2-oxazoles mediated by ZnI2 and FeCl3 is described. A Lewis acid promoted cyclization of acetylenic amide with various functionalities was well tolerated to give 2-oxazolines and 2-oxazoles in good to excellent yields under mild reaction conditions.