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DOI: 10.1055/s-2007-966068
Copper Hydride Catalyzed Enantioselective Conjugate Reduction of Unsaturated Nitriles
Publication History
Publication Date:
11 May 2007 (online)
Abstract
α,β-Unsaturated nitriles were reduced with high levels of enantioselectivity via copper hydride catalysis. In this procedure, bench-top stable copper(II) acetate and Josiphos ligand are used as the chiral catalyst and an inexpensive hydrosilane, polymethylhydrosiloxane (PMHS) is employed as the stoichiometric reducing agent. While the reactions are conducted at 0 °C in most cases, they also can be conducted at room temperature at enhanced rates with no significant drop in enantiomeric excess.
Key words
asymmetric catalysis - copper hydride - hydrosilanes - reduction - α,β-unsaturated nitriles
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1a
Harrowven DC.Pascoe DD.Demurtas D.Bourne HO. Angew. Chem. Int. Ed. 2005, 44: 1221 -
1b
Banfi L.Basso A.Gandolfo V.Guanti G.Riva R. Tetrahedron Lett. 2004, 45: 4221 -
1c
Mori K. Tetrahedron: Asymmetry 2005, 16: 685 -
1d
Andrus MB.Meredith EL.Hicken EJ.Simmons BL.Glancey RR.Ma W. J. Org. Chem. 2003, 68: 8162 -
1e
Abate A.Brenna E.Negri CD.Fuganti C.Serra S. Tetrahedron: Asymmetry 2002, 13: 899 -
2a
De Bellefon C.Fouilloux P. Catal. Rev. 1994, 36: 459 -
2b
Osborn ME.Pegues JF.Paquette LA. J. Org. Chem. 1980, 45: 168 - 3
Kim D.Park B.-M.Yun J. Chem. Commun. 2005, 1755 - 4
Lee D.Kim D.Yun J. Angew. Chem. Int. Ed. 2006, 45: 2785 - 5 (R)-(S)-Josiphos (R)-(S)-PPF-PCy2 = dicyclohexyl{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl}phosphine. For a review, see:
Blaser H.-U.Brieden W.Pugin B.Spindler F.Studer M.Togni A. Top. Catal. 2002, 19: 3 - 10 Its stereochemical assignment was made by comparison with the optical rotation of the corresponding ester derivative:
Appella DH.Moritani Y.Shintani R.Ferreira EM.Buchwald SL. J. Am. Chem. Soc. 1999, 121: 9473
References
BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthalene.
7p-Tol-BINAP = 2,2′-bis(di-4-tolylphosphino)-1,1′-bi-naphthalene.
8(R)-(S)-PPF-Pt-Bu2 = di-tert-butyl{(R)-1-[(S)-2-(diphenyl-phosphino)ferrocenyl]ethyl}phosphine.
9(R)-(S)-Cy2PF-PCy2 = dicyclohexyl{(R)-1-[(S)-2-(dicyclo-hexylphosphino)ferrocenyl]ethyl}phosphine.