<i>gem-</i>Difluoroolefination of Diazo Compounds with TMSCF<sub>3</sub> or TMSCF<sub>2</sub>Br: Transition-Metal-Free Cross-Coupling of Two Carbene Precursors
作者:Mingyou Hu、Chuanfa Ni、Lingchun Li、Yongxin Han、Jinbo Hu
DOI:10.1021/jacs.5b09888
日期:2015.11.18
fragment resulting from a diazocompound and a difluorocarbene fragment derived from Ruppert-Prakash reagent (TMSCF3) or TMSCF2Br, has been developed. This gem-difluoroolefination proceeds through the direct nucleophilic addition of diazocompounds to difluorocarbene followed by elimination of N2. Compared to previously reported Cu-catalyzed gem-difluoroolefination of diazocompounds with TMSCF3, which possesses
diazocompounds was developed to give gem-difluoroolefins, which constitutes a fast practical pathway to achieve hindered gem-difluoroolefins. The cross-coupling between difluorocarbene and aryl diazoacetates proceeded smoothly in the presence of a copper source, whereas its coupling with diaryl diazomethanes occurred well under metal-free conditions. A mechanism involving a copper–difluorocarbene complex
Palladium-Catalyzed Defluorinative Alkylation of gem-Difluoroalkenes with Cyclopropanols: Stereoselective Synthesis of γ-Fluorinated γ,δ-Unsaturated Ketones
作者:Lingyu Kong、Wenqing Ti、Aijun Lin、Hequan Yao、Yue Huang、Xuanyi Li
DOI:10.1021/acs.orglett.4c01045
日期:2024.5.3
A palladium-catalyzed defluorinative alkylation of gem-difluoroalkenes with cyclopropylalcohols was developed. A range of γ-fluorinated γ,δ-unsaturated ketones were constructed in good yields with excellent stereoselectivities. In addition, by base-mediated intramolecular nucleophilic vinylic substitution (SNV), the products could be further transformed to 2,5-dimethylenetetrahydrofurans and analogues
开发了钯催化的偕二氟烯烃与环丙醇的脱氟烷基化反应。以良好的产率构建了一系列具有优异立体选择性的 γ-氟化 γ,δ-不饱和酮。此外,通过碱介导的分子内亲核乙烯基取代(S N V),产物可以进一步转化为具有优异立体选择性的2,5-二亚甲基四氢呋喃及其类似物。
Nickel‐Catalyzed Stereo‐ and Enantioselective Cross‐Coupling of
<i>gem</i>
‐Difluoroalkenes with Carbon Electrophiles by C−F Bond Activation
作者:Ziqi Zhu、Lin Lin、Jieshuai Xiao、Zhuangzhi Shi
DOI:10.1002/anie.202113209
日期:2022.2
AbstractStereo‐ and enantioselective cross‐electrophile coupling involving C−F bond activation is reported. Treatment of gem‐difluoroalkenes with racemic benzyl electrophiles in the presence of a chiral nickel complex using B2pin2 as a stoichiometric reductant allows the construction of a C(sp2)−C(sp3) bond under mild conditions, affording a broad range of monofluoroalkenes bearing stereogenic allylic centers. Initial mechanistic studies indicate that a radical chain pathway may be operating, wherein the ester group in the gem‐difluoroalkene promotes C−F bond activation through oxidative addition to a Ni species.