Kinetic and Theoretical Study of 4-<i>e</i><i>xo</i> Ring Closures of Carbamoyl Radicals onto CC and CN Bonds
作者:Gino A. DiLabio、Eoin M. Scanlan、John C. Walton
DOI:10.1021/ol047716+
日期:2005.1.1
Carbamoyl radicals were generated from oxime oxalate amides, and the kinetics of their 4-exo cyclizations onto C=C and C=NO bonds, leading to beta-lactam-containing species, were studied by EPR spectroscopy. DFT computations with model carbamoyl radicals predicted 4-exo ring closures onto C=NO bonds to be facile, especially when tert-butyl substituents were present. The reverse ring-opening reactions
氨基甲酸酯基由肟草酸酯酰胺生成,并通过EPR光谱研究了它们的4-exo环化反应在C = C和C = NO键上的动力学,导致形成含β-内酰胺的物种。用模型氨基甲酰基基团进行的DFT计算预测C = NO键上的4-exo环闭合是容易的,特别是在存在叔丁基取代基的情况下。反向开环反应预计具有更高的活化能。实验证据也支持缓慢的反向开环。