Corporate Research & Development Division, Takasago International Corporation , 1-4-11 Nishi-Yawata, Hiratsuka, Kanagawa 254-0073, Japan.
Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology , 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
J Am Chem Soc. 2016 Aug 17;138(32):10084-7. doi: 10.1021/jacs.6b05738. Epub 2016 Aug 5.
A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η(6)-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and triethylamine with an unprecedented level of excellent enantioselectivity. For the non-ortho-substituted benzophenones, the oxo-tethered catalyst electronically discerned biased substrates, resulting in attractive performance yielding chiral diarylmethanols with >99% ee.
双功能钌配合物中 1,2-二苯乙烯二胺（DPEN）与η（6）-芳基配体之间的醚键促进了二芳基酮的简洁不对称转移氢化反应。由于对芳基上邻位取代基的有效区分，不对称二苯甲酮在甲酸和三乙胺的 5:2 混合物中被顺利还原，具有前所未有的高对映选择性。对于非邻位取代的二苯甲酮，氧化醚键化的催化剂在电子上区分了有偏向的底物，从而得到了手性二芳基甲醇，对映体过量值（ee）大于 99%。
