Silyl Anion Initiated Hydroboration of Aldehydes and Ketones
作者:Martin W. Stanford、Alessandro Bismuto、Michael J. Cowley
DOI:10.1002/chem.202000897
日期:2020.8.6
carbonyl compounds. Typically, transition‐metal or reactive main‐group hydride catalysts are used in conjunction with a mild reductant such as pinacolborane. The reactivity of the main‐group catalysts is a consequence of the nucleophilicity of their hydride ligands. Silicon hydrides are significantly less reactive and are therefore not efficient hydroboration catalysts. Here, a readily prepared silyl anion
Fe, Co) triplebonds. The cluster with two U≡Co triplebonds exhibits excellent catalytic activity for the hydroboration of alkynes under mild conditions, producing α-vinylboronates with good yields and regioselectivity. These heterometallic clusters represent the rare structurally authenticated example of multiple bonding between f-block elements and transitionmetals. Theoreticalstudies reveal high
Metal‐Free Allylic C−H Amination of Vinylsilanes and Vinylboronates using Silicon or Boron as a Regioselectivity Switch
作者:T. Parker Maloney、Janna L. Berman、Forrest E. Michael
DOI:10.1002/anie.202210109
日期:2022.11.7
A metal-free allylic C−H amination protocol allows simple vinylsilanes and vinylboronates to be selectively functionalized without competitive consumption of the reactive vinylmetalloid core structure, preserving its reactivity for future transformations such as cross-coupling or addition reactions. The silicon/boron group directs the regioselectivity of amination to the distal side of the C=C bond
diffraction. Subsequently, the catalytic activity of as a pre-catalyst for the hydroboration of alkynes and nitriles was investigated. It exhibited good functional group tolerance towards both terminal alkynes and nitriles under solvent-free and low-load conditions. The potential mechanism for the -catalyzed reaction of alkynes and nitriles with HBpin are proposed by the NMR spectroscopy of the intermediates
以水杨醛衍生物和2-氨基吡啶为原料合成了双核希夫碱铝配合物(,)。配合物 和 通过 NMR 和单晶 X 射线衍射进行了表征。随后,研究了其作为炔烃和腈的硼氢化反应预催化剂的催化活性。在无溶剂和低负载条件下,它对末端炔烃和腈表现出良好的官能团耐受性。通过中间体的核磁共振谱提出了炔烃和腈与 HBpin 催化反应的潜在机理。
.alpha.-Trimethylsilyl boronic esters. Pinacol lithio(trimethylsilyl)methaneboronate, homologation of boronic esters with [chloro(trimethylsilyl)methyl]lithium, and comparisons with some phosphorus and sulfur analogs