Synthesis of Chiral Tertiary Boronic Esters by Oxime-Directed Catalytic Asymmetric Hydroboration
作者:Veronika M. Shoba、Nathan C. Thacker、Andrew J. Bochat、James M. Takacs
DOI:10.1002/anie.201509137
日期:2016.1.22
now report that the oxime‐directed CAHB of alkyl‐substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime‐containing chiral tertiary boronic esters with yields up to 87 % and enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O‐substituted hydroxylamines, the generation of quaternary carbon stereocenters
手性硼酸酯是不对称合成中有用的中间体。先前我们已经表明,羰基定向催化不对称硼氢化(CAHB)是一种合成功能化伯和仲手性硼酸酯的有效方法。我们现在报告称,频哪醇硼烷(pinBH)的由肟取代的烷基取代的亚甲基和三取代的烯烃底物的CAHB可提供含肟的手性叔硼酸酯,其收率高达87%,对映体比率高达96:4。通过形成手性二醇和O-取代的羟胺,通过碳-碳偶联反应生成季碳立构中心,以及制备手性的3,4,4-三取代的异恶唑啉,证明了该方法的有效性。