Room Temperature Copper(II)-Catalyzed Oxidative Cyclization of Enamides to 2,5-Disubstituted Oxazoles via Vinylic C–H Functionalization
摘要:
A copper(11)-catalyzed oxidative cyclization of enamides to oxazoles via vinylic C-H bond functionalization at room temperature is described. Various 2,5-disubstituted oxazoles bearing aryl, vinyl, alkyl, and heteroaryl substituents could be synthesized in moderate to high yields. This reaction protocol is complementary to our previously reported iodine-mediated cyclization of enamides to afford 2,4,5-trisubstituted oxazoles.
Herein, a selective and efficient CO2-mediated Z to E isomerization of enamides is reported. Notably, CO2 acts as a promoter to form the key reaction intermediate. This protocol provides a novel method for the selective isomerization of enamides under mild conditions with moderate to excellent yields. The method exhibits a broad substrate scope, including late-stage modification of biorelevant molecules
在此,报道了烯酰胺的选择性且有效的CO 2介导的Z至E异构化。值得注意的是,CO 2充当形成关键反应中间体的促进剂。该方案提供了一种在温和条件下选择性异构化烯酰胺的新方法,具有中等至优异的产率。该方法具有广泛的底物范围,包括生物相关分子的后期修饰。通过循环伏安法 (CV) 和密度泛函理论 (DFT) 计算得出的机理见解提供了证据,证明中间体通过非常规的 C 中心模式促进了反应。
Room Temperature Copper(II)-Catalyzed Oxidative Cyclization of Enamides to 2,5-Disubstituted Oxazoles via Vinylic C–H Functionalization
作者:Chi Wai Cheung、Stephen L. Buchwald
DOI:10.1021/jo301332s
日期:2012.9.7
A copper(11)-catalyzed oxidative cyclization of enamides to oxazoles via vinylic C-H bond functionalization at room temperature is described. Various 2,5-disubstituted oxazoles bearing aryl, vinyl, alkyl, and heteroaryl substituents could be synthesized in moderate to high yields. This reaction protocol is complementary to our previously reported iodine-mediated cyclization of enamides to afford 2,4,5-trisubstituted oxazoles.