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Volumn 13, Issue 24, 2011, Pages 6564-6567

Intramolecular michael reaction of tert-butylsulfinyl ketimines: Asymmetric synthesis of 3-substituted indanones

Author keywords

[No Author keywords available]

Indexed keywords

IMINE; INDAN DERIVATIVE; KETIMINE; NITRILE;

EID: 84055219463     PISSN: 15237060     EISSN: 15237052     Source Type: Journal    
DOI: 10.1021/ol2028948     Document Type: Article
Times cited : (37)

References (43)
  • 19
    • 4544361465 scopus 로고    scopus 로고
    • Reports in this context are practically limited to organocatalytic processes; for some recent examples, see: (a) Fonseca, M. T. H.; List, B. Angew. Chem., Int. Ed. 2004, 43, 3958.
    • (2004) Angew. Chem., Int. Ed. , vol.43 , pp. 3958
    • Fonseca, M.T.H.1    List, B.2
  • 24
    • 77953299014 scopus 로고    scopus 로고
    • For an exhaustive review on the use of this chiral auxiliary in asymmetric synthesis, see: Robak, M. T.; Herbage, M. A.; Ellman, J. A. Chem. Rev. 2010, 110, 3600.
    • (2010) Chem. Rev. , vol.110 , pp. 3600
    • Robakm, T.1    Herbage, M.A.2    Ellman, J.A.3
  • 28
    • 84055165980 scopus 로고    scopus 로고
    • A small amount ca. 5% of the corresponding isoindoline was obtained along with the major reaction product
    • A small amount ca. 5% of the corresponding isoindoline was obtained along with the major reaction product.
  • 29
    • 59649119376 scopus 로고    scopus 로고
    • The addition of fluoroalkyl anions to ketimines was reportedly hampered; see: (a) Liu, J.; Zhang, L.; Hu, J. Org. Lett. 2008, 10, 5377.
    • (2008) Org. Lett. , vol.10 , pp. 5377
    • Liu, J.1    Zhang, L.2    Hu, J.3
  • 31
    • 84055180644 scopus 로고    scopus 로고
    • To the best of our knowledge, the combinationCF3TMS/fluoride source (i.e., TBAT: tetrabutylammonium difluorotriphenylsilicate) has never been reported as a base
    • To the best of our knowledge, the combinationCF3TMS/fluoride source (i.e., TBAT: tetrabutylammonium difluorotriphenylsilicate) has never been reported as a base.
  • 32
    • 84055180645 scopus 로고    scopus 로고
    • Control experiments with either reagent (CF3TMS or TBAT) have been carried out separately. In both cases unaltered starting materials were recovered, even after several hours at room temperature
    • Control experiments with either reagent (CF3TMS or TBAT) have been carried out separately. In both cases unaltered starting materials were recovered, even after several hours at room temperature.
  • 33
    • 84055221162 scopus 로고    scopus 로고
    • For details, see Supporting Information
    • For details, see Supporting Information.
  • 34
    • 84055186797 scopus 로고    scopus 로고
    • This transition state has been suggested according to the most stable conformation of the corresponding enamine, which was in turn obtained by an MM2 minimization. A stabilizing electrostatic interaction between the oxygen of the sulfinamide and the electrophilic ester carbonyl carbon leading to a rigid eight-membered boat-like transition state could explain the high diastereoselectivities observed. For similar eight-membered transition states in intramolecular Michael reactions, see ref 4
    • This transition state has been suggested according to the most stable conformation of the corresponding enamine, which was in turn obtained by an MM2 minimization. A stabilizing electrostatic interaction between the oxygen of the sulfinamide and the electrophilic ester carbonyl carbon leading to a rigid eight-membered boat-like transition state could explain the high diastereoselectivities observed. For similar eight-membered transition states in intramolecular Michael reactions, see ref 4.
  • 35
    • 84857796725 scopus 로고    scopus 로고
    • In an attempt to rationalize the performance of these uncommon bases, we suggest that the bulky noncoordinating tetrabutyl ammonium cation leads to a more reactive "metaloenamine" intermediate than the corresponding metal cation which could be stabilized by the negatively charged oxygen of the chiral sulfoxide group via a six-membered chelate
    • In an attempt to rationalize the performance of these uncommon bases, we suggest that the bulky noncoordinating tetrabutyl ammonium cation leads to a more reactive "metaloenamine" intermediate than the corresponding metal cation which could be stabilized by the negatively charged oxygen of the chiral sulfoxide group via a six-membered chelate.
  • 37
    • 84055221161 scopus 로고    scopus 로고
    • For details, see Supporting Information
    • For details, see Supporting Information.
  • 39
    • 33750357957 scopus 로고    scopus 로고
    • We also essayed the diastereodivergent reduction using L-selectride as the reducing agent, but low yields (30%) and diastereoselectivities (5:1 dr) were achieved. The reversal diastereofacial selectivity in the reductions of tert-butylsulfinilketimines by either NaBH4 or L-selectride has been described: Colyer, J. T.; Andersen, N. G.; Tedrow, J. S.; Soukup, T. S.; Faul, M. M. J. Org. Chem. 2006, 71, 6859.
    • (2006) J. Org. Chem. , vol.71 , pp. 6859
    • Colyer, J.T.1    Andersen, N.G.2    Tedrow, J.S.3    Soukup, T.S.4    Faul, M.M.5
  • 40
    • 84055221159 scopus 로고    scopus 로고
    • A cross-peak between the two methine protons in the NOESY spectrum of 4a allowed assignment of the relative stereochemistry of the new stereocenter. The stereochemical outcome is in agreement with the chelated transition state suggested for reductions of tert-butanesulfinimides with NaBH4 (see Supporting Information)
    • A cross-peak between the two methine protons in the NOESY spectrum of 4a allowed assignment of the relative stereochemistry of the new stereocenter. The stereochemical outcome is in agreement with the chelated transition state suggested for reductions of tert-butanesulfinimides with NaBH4 (see Supporting Information).


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