Efficientborylation of sp3 C–O bonds by supported Au catalysts is described. Au nanoparticles supported on TiO2 showed high activity under mild conditions employing low catalyst loading conditions without the aid of any additives, such as phosphine and bases. A variety of allyl, propargyl, and benzyl substrates participated in the heterogeneously catalyzed reactions to furnish the corresponding allyl
描述了负载型Au催化剂对sp 3 C–O键的有效硼化作用。负载在TiO 2上的Au纳米颗粒在温和条件下采用低催化剂负载条件显示出高活性,而无需任何添加剂,例如膦和碱。各种烯丙基,炔丙基和苄基底物参与了非均相催化反应,以高产率提供了相应的烯丙基,烯丙基和苄基硼酸酯。此外,Au / TiO 2对烯丙基和苄基醇的直接硼化也有效。基于Hammett研究和控制实验的机理研究表明,负载型Au催化剂上的sp 3 C–O键硼化通过S N进行1'型机制涉及碳阳离子中间体的形成。负载的金催化剂的高活性,可重复使用性和环境相容性以及反应体系的可扩展性使有价值的有机硼化合物的实际合成成为可能。
Deoxygenative Borylation of Secondary and Tertiary Alcohols
作者:Florian W. Friese、Armido Studer
DOI:10.1002/anie.201904028
日期:2019.7.8
Two different approaches for the deoxygenative radical borylation of secondary and tertiary alcohols are presented. These transformations either proceed through a metal‐free silyl‐radical‐mediated pathway or utilize visible‐light photoredox catalysis. Readily available xanthates or methyl oxalates are used as radical precursors. The reactions show broad substrate scope and high functional‐group tolerance
We describe a 1,3-boron shift-type reaction of homoallenylboronates at the center (sp) carbon in allenes to afford 2-boryl-1,3-dienes with a variety of substituents.
Borylation of Propargylic Substrates by Bimetallic Catalysis. Synthesis of Allenyl, Propargylic, and Butadienyl Bpin Derivatives
作者:Tony S. N. Zhao、Yuzhu Yang、Timo Lessing、Kálmán J. Szabó
DOI:10.1021/ja502792s
日期:2014.5.28
Bimetallic Pd/Cu and Pd/Ag catalytic systems were used for borylation of propargylic alcohol derivatives. The substrate scope includes even terminal alkynes. The reactions proceed stererospecifically with formal S(N)2' pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate.