- The enhanced asymmetric hydrogenation of unsymmetrical benzils to hydrobenzoin catalyzed by organosoluble zirconium phosphonate-immobilized ruthenium catalyst
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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.
- Du, Yu,Feng, Dandan,Wan, Jingwei,Ma, Xuebing
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- Stereoselective synthesis of optically active hydrobenzoins via asymmetric hydrogenation of benzils with Ru(OTf)(TsDPEN)(I·6- cymene) as the pre-catalyst
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Optically active hydrobenzoins are very important building blocks for further derivation of biologically active complexes, natural products, and pharmaceutical compounds. In this paper, A practical approach has been developed for asymmetric hydrogenation
- Huang, Xiaofei,Li, Naikai,Geng, Zhicong,Pan, Fengfeng,Wang, Xingwang
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p. 2657 - 2663
(2013/01/15)
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- Multifunctional catalyst useful in the synthesis of chiral vicinal diols and process for the preparation thereof, and process for the preparation of chiral vicinal diols using said multifunctional catalysts
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The present invention relates to a multifunctional reusable catalyst and to a process for the preparation thereof on a single matrix of the support to perform multicomponent reaction in a single pot. The multifunctional catalysts of the invention are usef
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- Multifunctional catalyst useful in the synthesis of chiral vicinal diols and process for the preparation thereof
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The present invention relates to a multifunctional reusable catalyst and to a process for the preparation thereof on a single matrix of the support to perform multicomponent reaction in a single pot. The multifunctional catalysts of the invention are useful for the synthesis of chiral vicinal diols by tandem and / or simultaneous reactions involving Heck coupling, N-oxidation and AD reaction of olefins in presence of cinchona alkaloid compounds both as an native one and immobilized one in the said matrix support. This invention also relates to a process for preparing vicinal diols by asymmetric dihydroxylation of olefins in presence of cinchona alkaloid compounds employing reusable multifunctional catalysts as heterogeneous catalysts in place of soluble osmium catalysts.
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