Carbon-13 nuclear magnetic resonance substituent-induced shieldings and conformational equilibriums in cyclohexanes

Schneider, H.‐J.; Hoppen, Volker

doi:10.1021/jo00414a017

Cited by 183 publications

(62 citation statements)

References 6 publications

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“…The a and y shielding trends at C1,2 and C4,5, respectively, are consistent with expectations based on a and y substituent effects in related monosubstituted molecules (3,5,11); however, the p substituent effects on C3 and C6 are not. Indeed in 1, C3, the carbon P to equatorial oxygen, is shielded by 2.20 pprn relative to C6.…”

Section: (Ii) Solution Nmr Spectrasupporting

confidence: 87%

“…The CH resonance at 82.20 pprn can be assigned with confidence to C2, the carbon bearing equatorial oxygen, by analogy with well-established stereochemical trends (5,11,12). Its counterpart, the C1 site bearing axial oxygen, is shielded by 6.50 pprn and appears at 75.70 ppm.…”

Section: (Ii) Solution Nmr Spectramentioning

confidence: 74%

“…One can test this hypothesis semi-quantitatively by considering the known P deshielding effect of 2.17 ppm in the equatorial conformation of methoxycyclohexane (3,5) and the observed y-gauche shielding effect of 5.31 ppm in 1 due to the axial oxygen. On this basis, one would predict that.…”

Section: (Ii) Solution Nmr Spectramentioning

confidence: 99%

“…Early definitive work in this area with respect to "C NMR was carried out using monosubstituted compounds ( 1 4 ) . Consequently, axial and equatorial a , P, y , and 6 substituent effects have now been delineated for a wide variety of monosubstituted cyclohexane derivatives (1)(2)(3)(4)(5)(6)(7).…”

Section: Introductionmentioning

confidence: 99%

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cis-Cyclohexano-9-crown-3 ether. Solid state and low-temperature solution stereochemistry as determined by X-ray crystallography and nuclear magnetic resonance spectroscopy

Buchanan¹,

Driega²,

Moghimi³

et al. 1993

Can. J. Chem.

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The X-ray crystal structure of the title material has been determined at −130 °C. Low-temperature 1H1H COSY, 13C1H HETCOR, and DEPT 13C NMR spectra have been recorded, which permit unambiguous assignments of all carbon resonances when ring inversion is slow on the NMR timescale. The limiting low-temperature solution phase 13C spectrum has many common features with the solid phase 13C CPMAS spectrum recorded at 300 K. Spectra for the 7,10-tetra-deuterio derivative have also been obtained and substituent influences on 13C shieldings are discussed in detail.

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Section: (Ii) Solution Nmr Spectrasupporting

confidence: 87%

Section: (Ii) Solution Nmr Spectramentioning

confidence: 74%

Section: (Ii) Solution Nmr Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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cis-Cyclohexano-9-crown-3 ether. Solid state and low-temperature solution stereochemistry as determined by X-ray crystallography and nuclear magnetic resonance spectroscopy

Buchanan¹,

Driega²,

Moghimi³

et al. 1993

Can. J. Chem.

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“…This implied that rather than an equatorial β-position in compound 1, the coumaroyl substituent on C-3 in compound 2 adopted an axial α-substitution. Due to this change, a gauche γ-effect on C-1 of compound 1 was caused by the axially oriented coumaroyl group at C-3 [16], which led to an upfield shift of 3.8 ppm for C-1 in the 13 C NMR spectrum, when compared with this same signal in compound 1 (Table 2). Furthermore, in the NOESY spectrum, H-3 was observed to show strong correlations with H-24 and H-2β, as well as relatively weak correlations with H-23 and H-2α, which was consistent with its presumed equatorial β-configuration.…”

Section: Resultsmentioning

confidence: 99%

New bioactive lupane triterpene coumaroyl esters isolated from Buxus cochinchinensis

Pan¹,

Acuña²,

Chai³

et al. 2014

Planta Med

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Five new lupane triterpene coumaroyl esters (1-5), together with betulin (6) and a known Buxus alkaloid, N-3-benzoyldihydrocyclomicrophylline F (7), were isolated from a CHCl 3 -soluble partition of a methanol extract of Buxus cochinchinensis Pierre ex Gagnep. (Buxaceae) collected in Vietnam. Isolation work was monitored using human colon cancer cells . The structures of the new compounds (1-5) were determined on the basis of spectroscopic data interpretation. In addition to their cytotoxicity against HT-29 cells and NF-κB (p65) inhibitory activity in an ELISA assay, all isolates, as well as two semi-synthetic compounds derived from betulin and 5, respectively, were also evaluated for their in vitro antiplasmodial activities against the drugresistant Dd2 strain of Plasmodium falciparum and antifungal effects on the growth of the pathogenic yeast Candida albicans. The new lupane triterpene coumaroyl esters (1-5), along with Conflict of InterestThe authors declare no conflict of interest. HHS Public Access

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Application of Molecular Mechanics Calculations to Organic Chemistry

Ōsawa

Musso

1982

Topics in Stereochemistry

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Carbon-13 nuclear magnetic resonance substituent-induced shieldings and conformational equilibriums in cyclohexanes

Cited by 183 publications

References 6 publications

cis-Cyclohexano-9-crown-3 ether. Solid state and low-temperature solution stereochemistry as determined by X-ray crystallography and nuclear magnetic resonance spectroscopy

cis-Cyclohexano-9-crown-3 ether. Solid state and low-temperature solution stereochemistry as determined by X-ray crystallography and nuclear magnetic resonance spectroscopy

New bioactive lupane triterpene coumaroyl esters isolated from Buxus cochinchinensis

Application of Molecular Mechanics Calculations to Organic Chemistry

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