The stereoselectivealkenylation of unsaturated compounds by means of a (Z)-alkenyl sulfone-titanocene(II) system is described. Treatment of alkynes and (Z)-alkenyl methyl sulfones with the titanocene(II) reagent Cp2Ti[P(OEt)3]2 produced conjugated dienes. This alkenylation system is also applicable to polar CO bonds; the simple mixing of carbonyl compounds, (Z)-alkenyl methyl sulfones, and the titanocene(II)
描述了借助于(Z)-烯基砜-噻吩并茂(II)系统的不饱和化合物的立体选择性烯基化。用钛茂(II)试剂Cp 2 Ti [P(OEt)3 ] 2处理炔烃和(Z)-烯基甲基砜可制得共轭二烯。该烯基化体系也适用于极性C O键。羰基化合物,(Z)-烯基甲基砜和钛茂(II)试剂的简单混合形成了烯丙醇。烯基化的优点是它不需要制备烯基金属试剂,并且可以完全立体选择性地进行。
Decarboxylative Negishi Coupling of Redox‐Active Aliphatic Esters by Cobalt Catalysis
作者:Xu‐Ge Liu、Chu‐Jun Zhou、E. Lin、Xiang‐Lei Han、Shang‐Shi Zhang、Qingjiang Li、Honggen Wang
DOI:10.1002/anie.201806799
日期:2018.10
A cobalt‐catalyzed decarboxylative Negishi coupling reaction of redox‐active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkyl–aryl, alkyl–alkenyl, and alkyl–alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (±)‐preclamol
作者:Qi-Liang Yang、Yi-Kang Xing、Xiang-Yang Wang、Hong-Xing Ma、Xin-Jun Weng、Xiang Yang、Hai-Ming Guo、Tian-Sheng Mei
DOI:10.1021/jacs.9b11915
日期:2019.12.4
Synergistic use of electrochemistry and organometallic catalysis has emerged as a powerful tool for site-selective C-H functionalization, yet this type of transformation has thus far mainly been limited to arene C-H functionaliza-tion. Herein, we report the development of electrochemi-cal vinylic C-H functionalization of acrylic acids with al-kynes. In this reaction an iridium catalyst enables C-H/O-H
Switch in Selectivity for Formal Hydroalkylation of 1,3‐Dienes and Enynes with Simple Hydrazones
作者:Leiyang Lv、Lin Yu、Zihang Qiu、Chao‐Jun Li
DOI:10.1002/anie.201915875
日期:2020.4.16
anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes
Electrochemically driven, Cp*Ir(III)-catalyzed regioselective annulative couplings of benzoicacids with alkynes have been established herein. The combination of iridium catalyst and electricity not only circumvents the need for stoichiometric amount of chemical oxidant, but also ensures broad reaction compatibility with a wide array of sterically and electronically diverse substrates. This electrochemical