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Volumn 72, Issue 19, 2007, Pages 7071-7082

DFT and NMR studies of 2JCOH, 3J HCOH, and 3JCCOH Spin-couplings in saccharides: C-O torsional bias and H-bonding in aqueous solution

Author keywords

[No Author keywords available]

Indexed keywords

GLYCOSIDIC BOND CONFORMATION; HYDROXYL PROTONS; KARPLUS EQUATION; TORSION ANGLES;

EID: 34548714101     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo0619884     Document Type: Article
Times cited : (68)

References (49)
  • 22
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    • Frisch, M. J. et al. Gaussian98, Revision A.9; Gaussian, Inc.: Pittsburgh, PA, 1998.
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    • Frisch, M. J. et al. Gaussian94; Gaussian, Inc.: Pittsburgh, PA, 1995.
    • (1995) Gaussian94
    • Frisch, M.J.1
  • 28
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    • Frisch, M. J. et al. Gaussian03, Revision A.I; Gaussian, Inc., Pittsburgh PA, 2003.
    • Frisch, M. J. et al. Gaussian03, Revision A.I; Gaussian, Inc., Pittsburgh PA, 2003.
  • 29
    • 34548799826 scopus 로고    scopus 로고
    • Synthesis of 18 and 19: see ref 14 and refs therein. For 17: see ref 23. For 20: A detailed description will be reported elsewhere. Briefly, methyl β-D-[4-13C]glucopyranoside was prepared from D-[4-13C]glucose via Fischer glycosidation using Dowex 50 H, ion exchange resin as a catalyst. The methyl glycoside was converted to its 2,3,6-tri-O-benzyl derivative via a 2,3-di-O-benzyl-4,6-O-benzyidene intermediate. The tribenzyl derivative was condensed with 2,3,4,6-tetra-O-acetyl-D-[1- 13C]galactopyranosyl trichloroacetimidate in the presence of a TMSOTf catalyst; the imidate was prepared from D-[1-13C] galactose. Deprotection with NaOMe and Pt-C/H2 afforded 20, which was identified by its characteristic 13C chemical shifts. 23
    • 23
  • 35
    • 34548741848 scopus 로고    scopus 로고
    • The accuracy of small J-couplings measured directly from hydroxyl proton signals will be affected by resonance line-width. When the line-width becomes comparable to the J-coupling, the observed splitting yields an apparent coupling that is smaller than the actual value by 0.2-0.3 Hz. Under these conditions, couplings should be determined by spectral simulation.
    • (e) The accuracy of small J-couplings measured directly from hydroxyl proton signals will be affected by resonance line-width. When the line-width becomes comparable to the J-coupling, the observed splitting yields an apparent coupling that is smaller than the actual value by 0.2-0.3 Hz. Under these conditions, couplings should be determined by spectral simulation.
  • 37
    • 0000613049 scopus 로고    scopus 로고
    • Hydroxyl proton exchange rates were measured by saturation-transfer as described previously (Serianni, A. S, Pierce, J, Huang, S. G, Barker, R. J. Am. Chem. Soc. 1982, 104, 4037-4044, Hydroxyl proton signal intensities decayed exponentially as a function of water signal saturation time, and the decay time constant, τ1, was related to the desired exchange rate constant, kex, by l/τ1, l/T1, kex, where T1 is the spin-lattice relaxation time of the hydroxyl proton. T1 was determined from the relationship, M z-(∞)/Mz(0, τ1/T 1. Rate constants of 1.1-1.7 s-1 (±0.3 s -1) were observed at -20°C in 2:3 H2O/acetone- d6. Measurements were made on a 600 MHz NMR
    • 6. Measurements were made on a 600 MHz NMR.
  • 44
    • 34548758609 scopus 로고    scopus 로고
    • 6.
    • 6.
  • 46
    • 34548762048 scopus 로고    scopus 로고
    • Measurements of 3JHCOH and 3JCCOH in 24 labeled with 13C at Cl in 2:3 H2O/acetone-d6 solvent at -20°C gave the following values: 3JH2,O2H, ∼3-0 Hz; 3JC1,O2H, ∼3.0 Hz; 3J H.3,O3H, 6-0 Hz; 3JH4,O4H, 5.5 Hz; 3J/H6.O6H, 5.1 Hz; 3J H2′,O2H, 4.6 Hz; 3J H3′,O3′H, 4.4 Hz, 3J H6′,O6′H, 6.3 Hz. These data reveal an increase in 3JH6′,O6′H to 6.3 Hz relative to that observed in 15 5.6 Hz, Likewise, 3JH2,O2H and 3JC1,O2H differ in 16/19 and 24, and 3JH3′,O3′H is red
    • H3′,O3′H is reduced in 24 relative to the corresponding value in 15. Taken collectively, these results support the presence of bias in the C3′-O3′, C6′-O6′, and C2-O2 bond torsions in 24.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.