导向碳氢硼化:从金属催化到非金属转化  

Directed C–H borylation:From metal catalysis to metal free

作　　者：吕佳杭 史壮志 Jiahang Lü;Zhuangzhi Shi(State Key Laboratory of Coordination Chemistry,School of Chemistry and Chemical Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学化学化工学院配位国家重点实验室,南京210023

出　　处：《科学通报》2022年第32期3823-3835,共13页Chinese Science Bulletin

基　　金：国家自然科学基金(22025104,21972064)资助。

摘　　要：有机硼化合物是现代合成化学中应用最广泛的试剂之一,开发更加绿色经济的合成方法具有重要意义.在过去的十几年里,芳杂环化合物导向碳氢硼化反应的研究取得了令人瞩目的进展,其反应体系也正在从贵金属催化逐渐转移到更加绿色的非金属体系,但是在众多相似性质化学键中实现某一特定位点的选择性硼化仍具有高度挑战性.本文主要从以下两个方面介绍芳杂环化合物的邻位选择性硼化反应,包括:(1)过渡金属催化芳杂环化合物导向碳氢硼化;(2)非金属参与的芳杂环化合物导向碳氢硼化.导向碳氢硼化正从金属催化过渡到非金属参与,突破了传统手段对金属催化剂的依赖,拓宽了配位导向碳氢官能团化的概念.Organoborons play a highly important role in many science fields,range from synthetic chemistry to materials science to medicinal chemistry.The C-H borylation strategy has made significant development in recent decades,and its reaction system is changing from noble-metal catalysis to more environmentally friendly metal-free systems.Typically,an organic molecule contains multiple C-H bonds with subtle difference in activation barrier.Therefore,controlling the positional selectivity represents a key challenge in complex molecules.To override this intrinsic selectivity,introducing a directing group in molecules can exhibit different site-selectivity.This review focuses on the development of ortho-selective borylation of(hetero)arenes by various directing groups,including:(1)Metal-catalyzed directed C-H borylation;and(2)metal-free directed C-H borylation.The directed C-H borylation is shifting from noble metals to metal-free systems,breaking through the dependence of traditional means on metal catalysts and broadening the concept of C–H functionalization.In the first section,the development of transition metal catalysts for directed C-H borylation is summarized.Among various catalysts,the iridium complexes have proven to be most active toward C-H borylation.The 16e intermediate[Ir(dtbpy)(Bpin)3](dtbpy=4,4′-di-tert-butyl-2,2′-bipyridine,Bpin=4,4,5,5-tetramethyl-1,3,2-dioxaborolane)has been proved to be the catalytically active species in the[Ir(X)(cod)]2/dtbpy(X=OMe or Cl,cod=1,5-cyclooctadiene)catalyzed directed C-H borylation.Three different strategies have been developed for the direct regioselective C-H bond borylation:Chelate directed,relay directed,and outer-sphere directed.Notably,dimethylsilyl can be employed as the directing group in Ir-catalyzed ortho-borylation of arenes.In addition to iridium,the use of other transition metal catalysts including rhodium and palladium has met some success as well.The second section first analyses the disadvantages of traditional C-H borylation by transition metal cata

关 键 词：碳氢官能团化 有机硼化物 金属催化 非金属硼化 芳杂环 

分 类 号：TQ426[化学工程]