- Chiral spiro compounds and their use in asymmetric catalytic reactions
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The present invention provides a chiral ligand, represented by a formula or its enantiomer: X and X′ can be independently O, NH, NR, NCOR or S; each of Z1-Z7 and Z1′-Z7′ can be independently H, alkyl, aryl, substituted alkyl, substituted aryl, alkoxyl, aryloxyl, nitro, amide, aryoxide, halide, hydroxyl, carboxylate, hetereoaryl, or a cyclic alkene, fused aryl, or cyclic ether group formed from any two adjacent Z groups or any two adjacent Z′ groups; Y and Y′ can be independently OH, OR, NH2, NHR, NR2, SH, PR2, OPR2, NHPR2, OP(OR)2, COOH, COOR, CONHR, or a linking group formed from Y and Y′ groups together. Processes of preparing these ligands, catalysts that employ them and methods of using the catalysts are also provided.
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Page/Page column 13; 20-21
(2008/06/13)
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- Synthesis of new monodentate spiro phosphoramidite ligand and its application in Rh-catalyzed asymmetric hydrogenation reactions
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(Chemical Equation Presented) A new spirocyclic diol, 9,9′- spirobixanthene-1,1′-diol, was synthesized in two steps from readily available starting material m-phenoxyanisole. Resolution of the racemic diol was achieved by cocrystallization with N-benzylcinchondimium chloride and N-benzylquininium chloride in acetonitrile. The corresponding spiro monodentate phosphoramidite ligand has been prepared for Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid derivatives and itaconic acid with excellent enantioselectivities (up to >99% ee).
- Wu, Shulin,Zhang, Weicheng,Zhang, Zhaoguo,Zhang, Xumu
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p. 3565 - 3567
(2007/10/03)
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