- Synthesis of novel C2 and C1 symmetric chiraphos derivatives and their application in palladium-catalyzed miyauramichael reaction
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A new method for the synthesis of C2 and C1 symmetric CHIRAPHOS derivatives and their application in Pd-catalyzed 1,4-addition reaction of an aryl boron compound to an ,￠-unsaturated carbonyl compound (MiyauraMichael reaction) are described. Six CHIRAPHOS congeners are prepared by substitution reactions of (2R,3R)-butane-2,3-diyl ditosylate with metalated phosphineborane adducts and subsequent deprotection of the resulting borane-protected bisphosphines. In the asymmetric MiyauraMichael reaction, the CHIRAPHOS derivative containing 4-tolyl groups showed a higher enantioselectivity than the others including parent CHIRAPHOS.
- Jin, Masayoshi,Nakamura, Masaharu
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p. 1035 - 1037
(2013/09/24)
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- Highly Active and Selective Ethylene Oligomerization Catalyst and Method of Preparing Hexene or Octene Using the Same
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This invention relates to a chromium complex compound for selective ethylene oligomerization including a chiral ligand, and to a method of selectively preparing 1-hexene or 1-octene from ethylene using the same.
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Page/Page column 7
(2012/06/01)
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- Ethylene oligomerization catalyst systems having enhanced selectivity
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Disclosed herein is a catalyst system for selective oligomerization of ethylene, which comprises a P—C—C—P frame-work ligand, which is (R1)(R2)P—(R5)CHCH(R6)—P(R3)(R4), and a chromium-based metal compound. Also disclosed is a method of greatly enhancing the activity and selectivity of oligomerization, such as trimerization or tetramerization, using a ligand having a specific steric arrangement structure.
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Page/Page column 11; 12
(2013/02/27)
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- ETHYLENE TETRAMERIZATION CATALYST SYSTEMS AND METHOD FOR PREPARING 1-OCTENE USING THE SAME
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Disclosed herein is a method of preparing 1-octene at high activity and high selectivity while stably maintaining reaction activity by tetramerizing ethylene using a chromium-based catalyst system comprising a transition metal or a transition metal precursor, a cocatalyst, and a P—C—C—P backbone structure ligand represented by (R1)(R2)P—(R5)CHCH(R6)—P(R3)(R4).
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Page/Page column 4
(2010/06/16)
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- Michael Addition of Lithiodiphenylphosphine to Menthyloxy-2-Furanone: Enantioselective Synthesis of S,S-CHIRAPHOS
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The preparation of enantiomerically pure (2S,3S)-2,3-bis(diphenylphosphino)butane (S,S-CHIRAPHOS) in 35percent overall yield from readily available γ-menthoxybutenolide is described.
- Jansen, Johan F. G. A.,Feringa, Ben L.
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p. 719 - 720
(2007/10/02)
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- PREPARATION AND 31P NMR STUDIES OF PLATINUM COMPLEXES OF SOME CHIRAL, BIDENTATE PHOSPHINES
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Two chiral diphosphines of formula RN(P(C6H5)2)2, S-peap and S-alap, have been prepared from S-α-phenethylamine and the ethyl ester of S-alanine, respectively.Their syntheses, and the preparation of the achiral diphosphine beap, N,N'-bis(diphenylphosphino)-N,N'-dibenzylethylenediamine, are described.Platinum complexes of these bidentate ligands of formula Pt(chelate)CH3Cl and ClO4 (X=acetone; p-YC5H4N, when Y=CH3, C2H5, CHO, CO2CH3, H and N(CH3)2; and a series of monodentate, Group V donor ligands, P(C2H5)3, P(C3H7)3, P(C8H17)3, PCH3(C6H5)2, P(CH3)2C6H5, P(C6H5)3, P(C6H11)(C6H5)2, P(C6H11)2C6H5, P(C6H11)3, P(C6H5)2N(C2H5)2, As(C6H5)3 and Sb(C6H5)3) have been prepared and their 1H and 31P NMR parameters recorded.The cationic pyridine complexes show a correlation of the ρ values of the para substituent to some of the 31P chemical shifts and coupling constants.The steric and electronic properties of the diphosphine ligands have been investigated by comparing their 31P NMR parameters with those of analogous complexes containing (+)-diop and S,S-chiraphos.
- Payne, Nicholas C.,Stephan, Douglas W.
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p. 203 - 222
(2007/10/02)
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