作者:Youla Su、Shang Gao、Yue Huang、Aijun Lin、Hequan Yao
DOI:10.1002/chem.201502418
日期:2015.10.26
A solvent‐controlled C2/C5‐selective alkenylation of 3,4‐disubstituted pyrroles has been developed. The C3 substituent of pyrroles proved crucial to the regioselectivity. Substrates bearing directing groups at the C3 position exhibited excellent C2‐selectivities in chelation‐assisted CH activation in toluene or 1,4‐dioxane. However, a DMSO/DMF solvent system could override the chelation effect of
已开发出一种由溶剂控制的3,4-二取代吡咯的C2 / C5选择性烯基化。吡咯的C 3取代基被证明对区域选择性至关重要。在甲苯或1,4-二恶烷中,在螯合辅助的CH活化中,在C3位置带有导向基团的底物表现出出色的C2选择性。但是,DMSO / DMF溶剂系统可以取代弱方向性基团(如羧酸根和羰基)的螯合作用,从而有利于对电子含量更高的C5位置的区域选择性。测试了一系列3-羧酸盐和3-羰基吡咯,显示出中等至良好的收率,对C2-和C5-烯基化过程均具有良好的区域选择性。