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Volumn 21, Issue 17, 2010, Pages 2158-2166

Investigations of enantioreversal in both direct and directed enantioselective aldol reactions catalyzed by CuCl2[(-)-sparteine] and NiCl2[(-)-sparteine] complexes

Author keywords

[No Author keywords available]

Indexed keywords

COPPER CHLORIDE; COPPER COMPLEX; NICKEL CHLORIDE; NICKEL COMPLEX; SPARTEINE;

EID: 77956185323     PISSN: 09574166     EISSN: 1362511X     Source Type: Journal    
DOI: 10.1016/j.tetasy.2010.07.008     Document Type: Article
Times cited : (11)

References (50)
  • 19
    • 0033936085 scopus 로고    scopus 로고
    • for an excellent comprehensive account on asymmetric Diels-Alder, aldol, ene, and Michael additions see: J.S. Johnson, and D.A. Evans Acc. Chem. Res. 33 2000 325
    • (2000) Acc. Chem. Res. , vol.33 , pp. 325
    • Johnson, J.S.1    Evans, D.A.2
  • 21
    • 0018359796 scopus 로고
    • Absolute configuration of the aldol adducts are tentatively assigned (R) or (S) by comparison with relative signs of the specific rotations data of aldol with those reported for 5a and 5g as reference compounds, see: T. Sugasawa, and T. Toyoda Tetrahedron Lett. 16 1979 1423 By this analogy, a (+)-aldol adduct is tentatively assigned as the (R)-isomer while a (-)-aldol adduct is assigned as the (S)-isomer
    • (1979) Tetrahedron Lett. , vol.16 , pp. 1423
    • Sugasawa, T.1    Toyoda, T.2
  • 23
    • 10844258853 scopus 로고    scopus 로고
    • For a recent review on double catalytic activation (DCA) protocol: see S. Kanemasa, and K. Ito Eur. J. Org. Chem. 2004 4741
    • (2004) Eur. J. Org. Chem. , pp. 4741
    • Kanemasa, S.1    Ito, K.2
  • 27
    • 0003438540 scopus 로고
    • 3rd ed. Cornell University Press New York
    • Fluoride anions show an extremely high affinity for the silicon atom due to high homolytic bond energy; see: L. Pauling The Nature of Chemical Bond 3rd ed. 1960 Cornell University Press New York Chapter 3. This property enables its routine use in organic synthesis as deprotecting agents for silyl groups
    • (1960) The Nature of Chemical Bond
    • Pauling, L.1
  • 28
    • 20944436033 scopus 로고    scopus 로고
    • To the best of our knowledge until now there is no report for the enantioselective direct aldol reaction of aromatic aldehydes and methylvinylketone (MVK) under catalytic conditions. For direct aldol reaction of aliphatic aldehydes with methylvinylketone (MVK); see: B.M. Trost, S. Shin, and J.A. Sclafani J. Am. Chem. Soc. 127 2005 8602
    • (2005) J. Am. Chem. Soc. , vol.127 , pp. 8602
    • Trost, B.M.1    Shin, S.2    Sclafani, J.A.3
  • 29
    • 77956181608 scopus 로고    scopus 로고
    • For direct aldol reaction of methylvinylketone (MVK) using catalyst 2, better yields and enantioselectivities were obtained in methanol. In contrast, for catalyst 1, the best solvent for the reaction is DMF. It should be noted that solvent independent enantioreversal with identical sign of the specific rotation occurs in both the solvents (DMF and MeOH) with catalysts 1 and 2
    • For direct aldol reaction of methylvinylketone (MVK) using catalyst 2, better yields and enantioselectivities were obtained in methanol. In contrast, for catalyst 1, the best solvent for the reaction is DMF. It should be noted that solvent independent enantioreversal with identical sign of the specific rotation occurs in both the solvents (DMF and MeOH) with catalysts 1 and 2.
  • 30
    • 53849129256 scopus 로고    scopus 로고
    • It is a popular misconception that the (+)-sparteine is not a natural product; however, although more narrowly distributed than its better known and commercially available antipode (-)-sparteine. It is well known that (+)-sparteine is biosynthesized by numerous plant species. Traditionally, (+)-sparteine has been most conveniently obtained from natural (±)-lupanine (2-oxosparteine), extracted from the seeds of Lupinus albus, by classical resolution followed by reduction of the resulting (-)-lupanine. For references see N.R. Norcross, J.P. Melbardis, M.F. Solera, M.A. Sephton, C. Kilner, L.N. Zakharov, P.C. Astles, S.L. Warriner, and P.R. Blakemore J. Org. Chem. 73 2008 7939
    • (2008) J. Org. Chem. , vol.73 , pp. 7939
    • Norcross, N.R.1    Melbardis, J.P.2    Solera, M.F.3    Sephton, M.A.4    Kilner, C.5    Zakharov, L.N.6    Astles, P.C.7    Warriner, S.L.8    Blakemore, P.R.9
  • 32
    • 77956188552 scopus 로고    scopus 로고
    • The cost of (+)-sparteine (as pachycarpine) is ca. three times greater than that typical for (-)-sparteine
    • The cost of (+)-sparteine (as pachycarpine) is ca. three times greater than that typical for (-)-sparteine.
  • 33
    • 77956185383 scopus 로고
    • More recently, (+)-sparteine itself has been discovered to be a minor alkaloid of Lupinus albus, see: W. Wysocka Sci. Legumes 2 1995 137 140
    • (1995) Sci. Legumes , vol.2 , pp. 137-140
    • Wysocka, W.1
  • 37
    • 77956189131 scopus 로고    scopus 로고
    • Degree of distortion from the planarity is reflected by the magnitude of dihedral angle between the MN2 plane and MCl2 plane, which is 67.0°and 81.3° for 1 and 2, respectively
    • Degree of distortion from the planarity is reflected by the magnitude of dihedral angle between the MN2 plane and MCl2 plane, which is 67.0°and 81.3° for 1 and 2, respectively.
  • 42
    • 77956183790 scopus 로고    scopus 로고
    • note
    • ij represents corresponding crystallographically observed bond angles. The atoms are labelled (1-4) in the order of decreasing bond lengths so that the corresponding bond angles between displacement vectors lie in the same asymmetric unit of the vector space defined by symmetry coordinates.
  • 43
    • 77956183122 scopus 로고    scopus 로고
    • note
    • 1) = 266.4°.
  • 45
    • 77956182946 scopus 로고    scopus 로고
    • The balance of electronic and steric factors in 1 and 2 complexes are directly reflected in the asymmetry of M-N bond lengths in their X-ray structures. The Cu-N1 facing the endo-ring has a shorter Cu-N bond length (Cu-N1 = 2.003 (3) Å) compared to 2.021 (3) Å for Cu-N2 facing the exo-ring. In complex 2, both Ni-N1 and Ni-N2 bond distances correspond to a more symmetric configuration with 2.032 (4) Å and 2.027 (4) Å, respectively, which is slightly longer than those observed in complex 1
    • The balance of electronic and steric factors in 1 and 2 complexes are directly reflected in the asymmetry of M-N bond lengths in their X-ray structures. The Cu-N1 facing the endo-ring has a shorter Cu-N bond length (Cu-N1 = 2.003 (3) ) compared to 2.021 (3) for Cu-N2 facing the exo-ring. In complex 2, both Ni-N1 and Ni-N2 bond distances correspond to a more symmetric configuration with 2.032 (4) and 2.027 (4), respectively, which is slightly longer than those observed in complex 1.


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