1612842-79-1Relevant articles and documents
The enhanced asymmetric hydrogenation of unsymmetrical benzils to hydrobenzoin catalyzed by organosoluble zirconium phosphonate-immobilized ruthenium catalyst
Du, Yu,Feng, Dandan,Wan, Jingwei,Ma, Xuebing
, p. 49 - 58 (2014)
In this article, a successful design on translating a heterogeneous catalysis of chiral zirconium phosphonate-supported ruthenium catalyst into a homogeneous system was developed by the covalent attachment of chiral (R,R)-1,2-diphenyl-ethylenediamine [(R,R)-DPEN] into the backbone of zirconium phosphonate with the different arm lengths (n = 2, 4, 6) and immobilization of [RuCl2(p-cymene)]2. Their catalytic performances in the homogeneous asymmetric transfer hydrogenation of unsymmetrical benzils with m- and p-substituents were enhanced, and the excellent activities (>97.1% conv.), diastereomeric and enantiomeric purities (syn/anti = 11.0-29.4, 91.8-99.2%ee syn) were achieved. These homogeneous supported Ru catalysts could be quantitatively and readily recovered by addition of ethyl acetate and centrifugation by solid/liquid separation, and be reused for five times without significant loss of their catalytic performances with 97.0% conv.; 95.6% syn and syn/anti = 20.7.