Palladium(II)-Catalyzed Coupling of Electron-Deficient Arenes via C–H Activation
摘要:
Homocoupling and cross-coupling of electron-deficient arenes, including nitrobenzene, (trifluoromethyl)benzene, ethyl benzoate, etc., have been developed to afford biaryls using a catalytic system of Pd(OAc)(2)/trifluoroacetic acid (TFA)/O-2 or K2S2O8. The crucial step is to tune the concentrations of arenes and the loading of TFA carefully to enhance the reaction rates and the selectivity of these couplings involving dual C-H activation.
Accessing Difluoromethylated and Trifluoromethylated
<i>cis</i>
‐Cycloalkanes and Saturated Heterocycles: Preferential Hydrogen Addition to the Substitution Sites for Dearomatization
作者:Xue Zhang、Liang Ling、Meiming Luo、Xiaoming Zeng
DOI:10.1002/anie.201907457
日期:2019.11.18
Reported here is a straightforward process in which a cyclic (alkyl)(amino)carbene/Rh catalyst system facilitates the preferential addition of hydrogen to the substitutionsites of difluoromethylated and trifluoromethylated arenes and heteroarenes, leading to dearomative reduction. This strategy enables the diastereoselective synthesis of cis-difluoromethylated and cis-trifluoromethylated cycloalkanes
Electrochemical Synthesis of Biaryls via Oxidative Intramolecular Coupling of Tetra(hetero)arylborates
作者:Arif Music、Andreas N. Baumann、Philipp Spieß、Allan Plantefol、Thomas C. Jagau、Dorian Didier
DOI:10.1021/jacs.9b12300
日期:2020.3.4
scope, scalability and robustness of this unconventional catalyst-free transformation, leading to functional-ized biaryls and ultimately furnishing drug-like small molecules as well as late stage derivatization of natural compounds. In addition, the observed selectivity of the oxidative coupling reaction is related to the electronic structure of the TABs through quantum-chemical calculations and experimental
Transition‐Metal‐Free Oxidative Cross‐Coupling of Tetraarylborates to Biaryls Using Organic Oxidants
作者:Carolin Gerleve、Armido Studer
DOI:10.1002/anie.202002595
日期:2020.9
tetraarylborates undergo selective (cross)‐coupling through oxidation with Bobbitt's salt to give symmetric and unsymmetric biaryls. The organic oxoammonium salt can be used either as a stoichiometric oxidant or as a catalyst in combination with in situ generated NO2 and molecular oxygen as the terminal oxidant. For selected cases, oxidative coupling is also possible with NO2/O2 without any additional
容易制备的四芳基硼酸盐通过用博比特盐氧化进行选择性(交叉)偶联,得到对称和不对称的联芳基化合物。有机氧铵盐可用作化学计量氧化剂或与原位产生的NO 2和作为末端氧化剂的分子氧组合用作催化剂。对于某些情况,也可以使用 NO 2 /O 2进行氧化偶联,无需任何额外的氮氧自由基助催化剂。四芳基硼酸盐的无过渡金属催化氧化配体交叉偶联是前所未有的,所引入的方法提供了获得各种联芳基和杂联芳基系统的途径。
A State-of-the-Art Cyanation of Aryl Bromides: A Novel and Versatile Copper Catalyst System Inspired by Nature
A general protocol for the cyanation of aryl halides with the nontoxic cyanide source K4[Fe(CN)6] using copper catalysis and a ligand system based on 1-alkylimidazoles is presented. The advantages of this system are the high selectivity, a unique substrate range, easy handling, and inexpensive reagents.