Nickel(II)-Magnesium-Catalyzed Cross-Coupling of 1,1-Dibromo-1-alkenes with Diphenylphosphine Oxide: One-Pot Synthesis of (<i>E</i>)-1-Alkenylphosphine Oxides or Bisphosphine Oxides
A novel nickel(II)‐magnesium‐mediated cross‐coupling of diphenylphosphine oxide with a variety of 1,1‐dibromo‐1‐alkenes has been developed, which provides a powerful and general methodology for the stereoselectivesynthesis of various (E)‐1‐alkenylphosphine oxides or bisphosphine oxides, with operational simplicity of the procedure, good to high yields and broad substrate applicability. Mechanistic
Z-Selective Addition of Diaryl Phosphine Oxides to Alkynes via Photoredox Catalysis
作者:Huamin Wang、Yongli Li、Zilu Tang、Shengchun Wang、Heng Zhang、Hengjiang Cong、Aiwen Lei
DOI:10.1021/acscatal.8b02617
日期:2018.11.2
Radical addition to alkynes is known to predominantly yield thermodynamically more stable E-alkenes. Control of stereoselectivity in these reactions, and the isolation of the higher-energy Z-alkenes, remain an important challenge in chemical synthesis. Herein, directsynthesis of Z-alkenylphosphine oxides via visible-light-induced radical addition to alkynes in water is reported. This protocol was
已知向炔烃中自由基加成主要产生热力学上更稳定的E-烯烃。这些反应中立体选择性的控制以及高能Z-烯烃的分离仍然是化学合成中的重要挑战。本文中,报道了通过可见光诱导的自由基加成至水中的炔烃直接合成Z-烯基膦氧化物。该方案对各种末端和内部炔烃均有效,可提供具有高Z-立体选择性的产物。此外,这种转化以克为单位进行了证明。机理研究支持以下结论:(1)通过自由基加成反应。(2)K 2 CO 3的选择因为水性碱对转化至关重要;(3)π–π堆积相互作用极大地提高了Z选择性。