S<sub>N</sub>2″-Selective and Enantioselective Substitution with Unsaturated Organoboron Compounds and Catalyzed by a Sulfonate-Containing NHC-Cu Complex
作者:Yuebiao Zhou、Ying Shi、Sebastian Torker、Amir H. Hoveyda
DOI:10.1021/jacs.8b10885
日期:2018.12.5
53-89% yield, 69-96% SN2″ selectivity, 98:2 to >98:2 E: Z ratio, and 94:6-98:2 er. Insight regarding several of the unique mechanistic attributes of the catalytic process was obtained on the basis of kinetic isotope effect measurements and DFT studies. These investigations indicate that cationic π-allyl-Cu complexes are likely intermediates, clarifying the role of the s-cis and s-trans conformers of
公开了第一个广泛适用的 SN2" 选择性和对映选择性催化取代策略。转化由 5.0 mol% 的含磺酸盐的 NHC-Cu 复合物(NHC = N-杂环卡宾)促进,并在市售的烯基-B(pin)(pin = pinacolato)或易于获得的甲硅烷基保护的炔丙基-B(pin)。发现无环、或芳基-、杂芳基-和烷基取代的五-2,4-二烯基磷酸酯,以及仅带有1,2-二取代烯烃或1,2-二取代和三取代烯烃的那些是合适的起始材料。环状磷酸二烯酯也可用作底物。以 51-82% 的收率获得了除 1,3-二烯基外还含有易于官能化的炔丙基部分(来自与丙二烯基-B(pin) 的反应)的产物,84-97% SN2" 选择性,89:11-97:3 E: Z 比和 86:14-98:2 对映体比 (er)。与甲硅烷基保护的炔丙基-B(pin) 化合物反应导致形成相应的甲硅烷基-烯丙基产物,产率 53-89%,SN2" 选择性