An Efficient [2 + 2 + 1] Synthesis of 2,5-Disubstituted Oxazoles via Gold-Catalyzed Intermolecular Alkyne Oxidation
Weimin He, Chaoqun Li and Liming Zhang*
*Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States, Email: zhangchem.ucsb.edu
W. He, C. Li, L. Zhang, J. Am. Chem. Soc., 2011, 133, 8482-8485.
DOI: 10.1021/ja2029188 (free Supporting Information)
An efficient intermolecular reaction of gold carbene intermediates generated via gold-catalyzed alkyne oxidation using nitriles as both the reacting partner and the reaction solvent offers 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.
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Oxazoles, 8-methylquinoline N-oxide