to be among the most valuable reagents in modern organic synthesis, providing a rapid access to a wide array of transformations, including the construction of C–C and C-heteroatom bonds, their use as dienophile-reactive groups has been rare. Herein we report the Diels–Alder (DA) reaction of (unsymmetrical) gem-diborylalkenes. These reactions provide a general and efficient method for the stereoselective
尽管偕二硼基烯烃被认为是现代有机合成中最有价值的试剂之一,可以快速进行各种转化,包括构建 C-C 和 C-杂原子键,但它们作为亲双烯反应基团的用途已经已经很少见了。在此,我们报道了(不对称)宝石二硼基烯烃的狄尔斯-阿尔德(DA)反应。这些反应为偕二硼基烯烃的立体选择性转化以快速获得1,1-双硼基环己烯提供了一种通用且有效的方法。使用与硼化二烯和偕二硼基烯烃相同的 DA 反应歧管,我们还开发了 1,1,2-三-和 1,1,3,4-四(硼酸盐)环己烯家族的简洁、高度区域选择性合成方法。目前缺乏有效合成途径的化合物。此外,DFT 计算可以深入了解控制这些 DA 反应的化学选择性、区域选择性和立体选择性的潜在因素。该方法还提供了偕二硼基降冰片烯的立体发散合成。开环复分解聚合(ROMP)证明了偕二硼基降冰片烯结构单元的实用性,为首次合成偕二硼基聚合物提供了高度模块化的方法。此外,这些聚合物已成功
Nickel(II)-Catalyzed Borylation of Alkenyl Methyl Ethers via C–O Bond Cleavage
A new protocol has been developed for the borylation of conjugated alkenyl methyl ethers using B2Pin2 via C–O bond cleavage catalyzed by Ni(II). In this cross-coupling reaction, both E/Z isomers of alkenyl ethers are converted into (E)-alkenyl boronic esters with good reactivity. This transformation exhibits high chemoselectivity in the presence of competitive C–O bonds such as aryl ether, ester, amide
aluminum-catalyzed hydroboration of a variety of nitriles and alkynes. Moreover, aluminum-catalyzed hydroboration is expanded to more challenging substrates such as alkene, pyridine, imine, carbodiimide, and isocyanides. More importantly, we have shown that the aluminum dihydride catalyzed both intra- and intermolecular chemoselective hydroboration of nitriles and alkynes over other reducible functionalities for
An efficient Cu-catalyzed C–H alkenylation with acyclic and cyclic vinyl boronates was realized for the first time under mild conditions. The scope of the vinyl borons and the compatibility with functional groups including heterocycles are superior than Pd-catalyzed C–H coupling with vinyl borons, providing a reliable access to multisubstituted alkenes and dienes. Subsequent hydrogenation of the product
Copper‐Photocatalyzed Hydroboration of Alkynes and Alkenes
作者:Mingbing Zhong、Yohann Gagné、Taylor O. Hope、Xavier Pannecoucke、Mathieu Frenette、Philippe Jubault、Thomas Poisson
DOI:10.1002/anie.202101874
日期:2021.6.21
photocatalytic hydroboration of alkenes and alkynes is reported. The use of newly-designed copper photocatalysts with B2Pin2 permits the formation a boryl radical, which is used for hydroboration of a large panel of alkenes and alkynes. The hydroborated products were isolated in high yields, with excellent diastereoselectivities and a high functional group tolerance under mild conditions. The hydroboration reactions
报道了烯烃和炔烃的光催化硼氢化反应。使用新设计的铜光催化剂和 B 2 Pin 2可以形成硼基自由基,该自由基可用于大量烯烃和炔烃的硼氢化反应。硼氢化产物以高产率分离,在温和条件下具有优异的非对映选择性和高官能团耐受性。硼氢化反应是在连续流动条件下开发的,以证明其合成效用。研究了反应机理,并提出了原位形成的硼酸盐和处于激发态的铜光催化剂之间的氧化反应,以形成硼基自由基。