Influence of the N-Substituents on the Nucleophilicity and Lewis Basicity of N-Heterocyclic Carbenes
作者:Alison Levens、Feng An、Martin Breugst、Herbert Mayr、David W. Lupton
DOI:10.1021/acs.orglett.6b01525
日期:2016.8.5
The ability to modulate the nucleophilicity and Lewis basicity of N-heterocyclic carbenes is pivotal to their application as organocatalysts. Herein we examine the impact of the N-substituent on the nucleophilicity and Lewis basicity. Four N-substituents popular in NHC organocatalysis, namely, the N-2,6-(CH3O)2C6H3, N-Mes, N-4-CH3OC6H4, and N-tert-butyl groups, have been examined and found to strongly
调节N-杂环卡宾的亲核性和Lewis碱性的能力对其作为有机催化剂的应用至关重要。在本文中,我们研究了N取代基对亲核性和Lewis碱性的影响。四个N取代基NHC有机催化,即流行Ñ -2,6-(CH 3 O)2 C ^ 6 ħ 3,Ñ -Mes,Ñ -4-CH 3 OC 6 H ^ 4,和Ñ -叔丁基已检查并发现它们对亲核性有强烈影响。因此,N -2,6-(CH 3 O)2 C6 ħ 3组提供了最亲核imidazolylidene NHC报告和Ñ -叔的至少丁基组之一。如最近报道的三烯基酯重排所观察到的,亲核性的这种差异反映在催化剂效率上。