Rh(III)-Catalyzed Decarboxylative Coupling of Acrylic Acids with Unsaturated Oxime Esters: Carboxylic Acids Serve as Traceless Activators
作者:Jamie M. Neely、Tomislav Rovis
DOI:10.1021/ja412444d
日期:2014.2.19
α,β-Unsaturated carboxylic acids undergo Rh(III)-catalyzed decarboxylative coupling with α,β-unsaturated O-pivaloyl oximes to provide substituted pyridines in good yield. The carboxylic acid, which is removed by decarboxylation, serves as a traceless activating group, giving 5-substituted pyridines with very high levels of regioselectivity. Mechanistic studies rule out a picolinic acid intermediate
α,β-不饱和羧酸与α,β-不饱和O-新戊酰基肟进行Rh(III)催化的脱羧偶联,以良好的收率提供取代的吡啶。通过脱羧去除的羧酸作为无痕活化基团,产生具有非常高区域选择性的 5-取代吡啶。机理研究排除了吡啶甲酸中间体,可分离的铑配合物进一步阐明了反应机理。