DMF-Catalyzed Direct and Regioselective C-H Functionalization: Electrophilic/Nucleophilic 4-Halogenation of 3-Oxypyrazoles
作者:Yuanyuan Liu、Guangke He、Kai Chen、Yin Jin、Yufeng Li、Hongjun Zhu
DOI:10.1002/ejoc.201100571
日期:2011.9
A novel, straightforward, and highly regioselective 4-chlorination of 3-oxypyrazole derivatives in boiling thionyl chloride (SOCl2) in the presence of catalytic N,N-dimethylformamide (DMF) has been developed. This reaction likely proceeds through a DMF-catalyzed electrophilic/nucleophilic chlorination mechanism and involves electrophilic attack by SOCl2 and nucleophilic substitution by Cl– as the key
在催化 N,N-二甲基甲酰胺 (DMF) 存在下,在沸腾的亚硫酰氯 (SOCl2) 中开发了一种新颖、直接且高度区域选择性的 3-羟基吡唑衍生物 4-氯化。该反应可能通过 DMF 催化的亲电/亲核氯化机制进行,并涉及 SOCl2 的亲电攻击和 Cl- 的亲核取代作为关键步骤。基于这种机理,通过分别向反应体系中加入 Br- 和 I-, 3-羟基吡唑类的相应 4-溴化和 4-碘化也得到了很好的收率。这种卤化方法可以快速访问许多原始的 4-halo-3-oxypyrazole 系列。