- 1,2-Bis(diphenylphosphino)-1-cyclohexylethane. A New Chiral Phosphine Ligand for Catalytic Chiral Hydrogenations
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The new chiral bidentate phosphine ligand (R)-1,2-bis(diphenylphosphino)-1-cyclohexylethane ((R)-Cycphos) has been prepared.The rhodium(I) cationic complex of this phosphine serves as an effective homogeneous asymmetric hydrogenation catalyst for the reduction of (Z)-α-amidoacrylic acids at ambient temperature and pressure.Optical yields for the corresponding (S)-α-amino acid derivatives that are produced are generally above 90percent.The success of this ligand in giving higher optical yields than those obtained from other structurally analogous phosphines is rationalized in terms of the bulky cyclohexyl substituent affording a more stereochemically rigid chelating phosphine.
- Riley, Dennis P.,Shumate, Robert E.
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- Process for producing optically active benzhydrol compounds
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A process for producing a benzhydrol compound (II) which comprises hydrogenating a benzophenone compound (I) in the presence of a hydrogenation catalyst consisting of a transition metal complex, a base and an optically active diamine compound: STR1 wherein R1 to R10 each represents H, OH, C1-4 alkyl, C1-4 alkoxy, C1-4 alkanoyl, etc., R2 and R3, and R8 and R9 may form --CH=CH--CH=CH--, or any two of R1 to R9 adjacent to each other may be bonded to thereby form --OCH2 O-- or --(CH2)3 --. By using this process, optically active benzhydrol compounds which have a high purity and are useful as, for example, intermediates in the synthesis of drugs can be produced by simple procedures.
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