Trifluoromethylation of Aryl and Heteroaryl Halides with Fluoroform-Derived CuCF<sub>3</sub>: Scope, Limitations, and Mechanistic Features
作者:Anton Lishchynskyi、Maxim A. Novikov、Eddy Martin、Eduardo C. Escudero-Adán、Petr Novák、Vladimir V. Grushin
DOI:10.1021/jo401423h
日期:2013.11.15
destabilized by CuX coproduced in the reaction, the magnitude of the effect paralleling the Lewis acidity of CuX: CuCl > CuBr > CuI. While SNAr and SRN1 mechanisms are not operational, there is a well-pronounced ortho effect, i.e., the enhanced reactivity of ortho-substituted aryl halides 2-RC6H4X toward CuCF3. Intriguingly, this ortho-effect is observed for R = NO2, COOH, CHO, COOEt, COCH3, OCH3, and even
最近在我们小组中发现的源自氟仿的CuCF 3对芳基和杂芳基卤化物表现出极高的反应活性,在没有额外配体的情况下表现最佳。各种各样的碘代芳烃在23–50°C下与“无配体” CuCF 3进行平滑的三氟甲基化反应,以几乎定量的产率得到相应的苯并三氟化物。许多低反应性的芳族溴化物也已被三氟甲基化,包括吡啶,嘧啶,吡嗪和噻唑衍生物以及带有吸电子基团和/或邻位取代基的芳基溴化物。只有最亲电子的氯代芳烃可以被三氟甲基化,例如2-氯烟酸。反应具有极高的化学选择性(没有芳烃,联芳基和C的侧链形成)2 F 5衍生物)可以以克级(最高20 mmol)高产率分离出大量的三氟甲基化产物。反应中共同产生的CuX使CuCF 3试剂不稳定,其影响程度与CuX的路易斯酸度平行:CuCl> CuBr> CuI。尽管S N Ar和S RN 1机制不起作用,但存在明显的邻位效应,即邻位取代的芳基卤化物2-RC 6 H 4 X对CuCF