Oxalohydrazide Ligands for Copper‐Catalyzed C−O Coupling Reactions with High Turnover Numbers
作者:Ritwika Ray、John F. Hartwig
DOI:10.1002/anie.202015654
日期:2021.4.6
long‐lived copper catalysts for couplings that form the C−O bonds in biaryl ethers. These Cu‐catalyzed coupling of phenols with aryl bromides occurred with turnovers up to 8000, a value which is nearly two orders of magnitude higher than those of prior couplings to form biaryl ethers and nearly an order of magnitude higher than those of any prior copper‐catalyzed coupling of aryl bromides and chlorides
The α-lithiobenzyloxy group, easily generated from aryl benzyl ethers by selective α-lithiation with t-BuLi at low temperature, behaves as a directed metalation group (DMG) providing a direct access to o-lithiophenyl α-lithiobenzyl ethers. This ortho-directing effect is reinforced in substrates bearing an additional methoxy group at the meta position. The generated dianions can be reacted with a selection
strength of their carbon–nitrogenbond. Here, we disclose that several ammonium salts can be readily activated using iridium photoredox catalysis to form radicals and illustrate the synthetic utility of this activation of strong C–N bonds with hydrodeamination reactions and radical couplings. Cyclic voltammetry was exploited to rationalize the reactivity observed for the activation of these ammonium
<i>N</i>-Methylation of Aniline Derivatives with CO<sub>2</sub> and Phenylsilane Catalyzed by Lanthanum Hydridotriarylborate Complexes bearing a Nitrogen Tridentate Ligand
A lanthanum amide complex, La(L)[N(SiHMe2)2](thf) (L = N,N″-bis(pentafluorophenyl)diethylenetriamine dianion, 1a), upon activation with B(3,4,5-F2C6H2)3 (2a), showed excellent catalytic activity for N-methylation of N-alkylaniline derivatives with CO2 in the presence of PhSiH3. A catalytically active lanthanum hydridotriarylborate complex, [La(L)(thf)2][HB(3,4,5-F3C6H2)3] (5aa), was generated via hydride
镧酰胺络合物,La( L )[N(SiHMe 2 ) 2 ](thf) ( L = N , N ″-bis(pentafluorophenyl)diethylenetriamine dianion, 1a ),用 B(3,4,5-F 活化2 C 6 H 2 ) 3 ( 2a )在PhSiH 3存在下对CO 2对N-烷基苯胺衍生物的N-甲基化表现出优异的催化活性。催化活性氢化三芳基硼酸镧络合物,[La( L )(thf) 2 ][HB(3,4,5-F3 C 6 H 2 ) 3 ] ( 5aa ) 是由中等路易斯酸2a在 THF 中通过氢化物从1a的 Si-H 部分中提取而生成的。CO 2氢化硅烷化步骤的 DFT 研究阐明了以下多种非共价相互作用是定位 HB(3,4,5-F 2 C 6 H 2 ) 3阴离子和 B(3,4,5-F 3 C 6的关键因素H 2 ) 3在CO 2的过渡态中靠近镧中心还原和