Sun Yuli, Lu Chengrong, Zhao Bei, Xue Mingqiang
J Org Chem. 2020 Aug 21;85(16):10504-10513. doi: 10.1021/acs.joc.0c00877. Epub 2020 Aug 5.
Four chiral dinuclear rare-earth metal complexes [REL] (RE = Y(), Eu(), Nd(), La ()) stabilized by Trost proligand HL (HL = (,)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) were first prepared, and all were characterized by X-ray diffraction. Complex was employed as the catalyst for enantioselective hydroboration reaction of substituted ketones, and the corresponding secondary alcohols with excellent yields and high ee values were obtained using reductant HBpin. The same result was also achieved using the combination of lanthanium amides La[N(SiMe)] with Trost proligand HL in a 1:1 molar ratio. The experimental findings and DFT calculation revealed the possible mechanism of the enantioselective hydroboration reaction and defined the origin of the enantioselectivity in the current system.
首次制备了四种由特罗斯特前体配体HL（HL = (,)-2,6-双[2-(羟基二苯基甲基)吡咯烷-1-基甲基]-4-甲基苯酚）稳定的手性双核稀土金属配合物[REL]（RE = Y()、Eu()、Nd()、La ()），并通过X射线衍射对其进行了表征。配合物 用作取代酮对映选择性硼氢化反应的催化剂，使用还原剂HBpin得到了产率优异且对映体过量值高的相应仲醇。使用摩尔比为1:1的镧酰胺La[N(SiMe)]与特罗斯特前体配体HL的组合也得到了相同的结果。实验结果和密度泛函理论计算揭示了对映选择性硼氢化反应的可能机理，并确定了当前体系中对映选择性的来源。
