Stereo- and Enantioselective Benzylic C–H Alkenylation via Photoredox/Nickel Dual Catalysis
作者:Xiaokai Cheng、Tongtong Li、Yuting Liu、Zhan Lu
DOI:10.1021/acscatal.1c02851
日期:2021.9.3
molecules undergo this cross-coupling reaction smoothly to afford chiral allylic compounds in up to 93% ee and >20/1 E/Z ratio under mild reaction conditions with good functional group tolerance. A triplet-energy-transfer-inhibiting strategy is developed for the stereoselective synthesis of alkenes under visible-lightphotocatalysis. The coordination pattern of nickel with chiral bis-imidazoline ligand has
报道了通过光氧化还原/镍催化的立体和对映选择性苄基 C-H 烯基化。容易获得的烷基苯和烯基溴化物,包括复杂的分子,在温和的反应条件下顺利地进行这种交叉偶联反应,以提供高达 93% ee 和 >20/1 E / Z比的手性烯丙基化合物,具有良好的官能团耐受性。开发了一种三重态能量转移抑制策略,用于在可见光光催化下立体选择性合成烯烃。基于非线性效应实验和 X 射线衍射,阐明了镍与手性双咪唑啉配体的配位模式。
Synthesis of 9-Fluorenylidenes via Pd-Catalyzed C–H Vinylation with Vinyl Bromides
作者:Shuai Yang、Yanghui Zhang
DOI:10.1021/acs.orglett.1c02722
日期:2021.10.15
A facile and efficient approach for the synthesis of 9-fluorenylidenes has been developed via the palladium-catalyzed cross-coupling of 2-iodobiphenyls and vinyl bromides. The reaction involves the C–H activation of 2-iodobiphenyls and dual C–C bond formations. A range of 9-fluorenylidene derivatives, including diphenyldibenzofulvenes, can be synthesized with the reaction.
Stereodivergent Synthesis of Both <i>Z</i>- and <i>E</i>-Alkenes by Photoinduced, Ni-Catalyzed Enantioselective C(sp<sup>3</sup>)–H Alkenylation
作者:Jitao Xu、Zhilong Li、Yumin Xu、Xiaomin Shu、Haohua Huo
DOI:10.1021/acscatal.1c04314
日期:2021.11.5
The enantio- and stereoselective synthesis of stereodefined alkenes, especially the functionalized Z-isomer with an allylic stereogenic center, remains a great challenge. We herein report an enantioselective benzylic C(sp3)–H alkenylation of simple alkylarenes with vinyl bromides via photoinduced nickel catalysis, which allows for the stereodivergent synthesis of both enantioenriched Z- and E-alkenes
An unprecedented iron/palladium-catalyzed reductive cross-coupling of alkenylbromides and bromodifluoromethanes with manganese as the reductant has been disclosed. A variety of functional groups was well tolerated, providing various substituted gem-difluoroallylenes in moderate to good yields. The preliminary mechanism studies ruled out the radical pathway for this new reaction.