Xue Qingquan, Huo Shangfei, Wang Tingyi, Wang Zeming, Li Jianli, Zhu Meifang, Zuo Weiwei
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, 201620, P. R. China.
Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
Angew Chem Int Ed Engl. 2020 May 18;59(21):8153-8159. doi: 10.1002/anie.202001561. Epub 2020 Apr 16.
Diphosphine ligands that merge both axial and P-centered chirality may exhibit superior or unique properties. Herein we report the diastereoselective introduction of P-centered chirality at the 2-position of the axially chiral 2'-(phosphine oxide)-1,1'-binaphthyl scaffold. A lithium-bromide exchange reaction of a 2-bromo-2'-(phosphine oxide)-1,1'-binaphthyl and treatment with dichlorophosphines followed by a nucleophilic organometallic reagent afforded unsymmetrical 2-phosphino-2'-(phosphine oxide)-1,1'-binaphthyls with binaphthyl axial chirality and one or two phosphorus stereocenters with a variety of P substituents. The final diastereomerically pure 2,2'-bisphosphino-1,1'-binaphthyls were obtained by reduction of the phosphine oxide directing group. Preliminary results demonstrated that a ligand with this hybrid chirality could induce higher stereoselectivity in the metal-complex-catalyzed asymmetric hydrogenation of a dialkyl ketone.
兼具轴向手性和磷中心手性的二膦配体可能具有优异或独特的性质。在此，我们报道了在轴向手性的2'-(氧化膦)-1,1'-联萘骨架的2-位上非对映选择性地引入磷中心手性。2-溴-2'-(氧化膦)-1,1'-联萘的锂-溴交换反应，然后用二氯膦处理，再与亲核有机金属试剂反应，得到了具有联萘轴向手性以及一个或两个磷立体中心且带有各种磷取代基的不对称2-膦基-2'-(氧化膦)-1,1'-联萘。通过还原氧化膦导向基团得到了最终的非对映体纯的2,2'-双膦基-1,1'-联萘。初步结果表明，具有这种混合手性的配体在金属络合物催化的二烷基酮不对称氢化反应中能够诱导更高的立体选择性。
