Conversion of a 3-Oxaquadricyclane to a Substituted Cyclobutane. Preparation and Proton Magnetic Resonance Spectra of Four Stereoisomeric 1,2-Diacetyl-3,4-dicarbomethoxycyclobutanes

1971 ◽  
Vol 49 (4) ◽  
pp. 574-582 ◽  
Author(s):  
J. Laing ◽  
A. W. Mcculloch ◽  
D. G. Smith ◽  
A. G. Mcinnes
Keyword(s):  
Magnetic Resonance ◽  
Computer Program ◽  
Long Range ◽  
Trans Isomer ◽  
Proton Magnetic Resonance ◽  
Ring System ◽  
Spin Interactions ◽  
Selective Deuteration ◽  
Cyclobutane Ring ◽  
Magnetic Resonance Spectra

Reaction of l,5-dicarbomethoxy-2,4-dimethyl-3-oxaquadricyclane with water gave a mixture of cis,cis,cis- and cis,cis,trans-1,2-diacetyl-3,4-dicarbomethoxycyclobutanes. The latter on treatment with acid epimerized to the corresponding trans,trans,trans-isomer, whereas the former yielded the trans,trans, cis-epimer together with 3,10-dimethyl-3,10-epoxy-5,8-dioxo-4,9-dioxatricyclo[5.3.0.02,6]decane which contains a new bridged ring system. The structure and stereochemistry of each compound was derived from symmetry considerations as reflected in its p.m.r. spectrum, and was facilitated by selective deuteration experiments. Vicinal and long-range spin–spin interactions between the cyclobutane ring hydrogens were deduced from pertinent p.m.r. sub-spectra using the NMRIT–NMREN computer program.

Proton magnetic resonance spectra of some benzo[b]thiophens. An investigation of substituent effects in a heteroaromatic system

1968 ◽  
Vol 21 (7) ◽  
pp. 1853 ◽  
Author(s):  
B Caddy ◽  
M Martin-Smith ◽  
RK Norris ◽  
ST Reid ◽  
S Sternhell
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Spin Coupling ◽  
Heteroaromatic System ◽  
Spin Spin Coupling ◽  
Magnetic Resonance Spectra

N.m.r. data for 19 5-substituted and 13 polysubstituted benzo[b]thiophens are tabulated. The influence of the substituents at C5 on the chemical shifts of H4 and H6 is discussed. Long-range interproton spin-spin coupling between H3 and H7, and between H2 and H6, is general in benzo[b]thiophens. The vicinal coupling J6,7 in 5-substituted benzo[b]thiophens varies directly and linearly with the electronegativity of the substituents at C5.

The proton magnetic resonance spectra of N-nitroso derivatives of sarcosine, proline and iminodiacetic acid

1971 ◽  
Vol 24 (9) ◽  
pp. 1949 ◽  
Author(s):  
FHC Stewart
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Iminodiacetic Acid ◽  
Conformational Isomerism ◽  
Nitroso Group ◽  
Restricted Rotation ◽  
Derivatives Of ◽  
Shielding Effects ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of various N-nitroso derivatives of sarcosine, L-proline, and iminodiacetic acid, including some protected dipeptides, have been obtained. Magnetic non-equivalence and conformational isomerism arising from restricted rotation of the nitroso group are discussed in relation to the reported behaviour of other nitrosamines. Long-range shielding effects on protons at a considerable distance from the anisotropic nitrosamino centre were readily detected with these compounds.

The proton magnetic resonance spectra of phenol in the absence of intermolecular proton exchange

1976 ◽  
Vol 54 (23) ◽  
pp. 3666-3671 ◽  
Author(s):  
Ted Schaefer ◽  
J. B. Rowbotham ◽  
Kalvin Chum
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Proton Exchange ◽  
Associated Species ◽  
Hydroxyl Protons ◽  
Model Support ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra in the absence of intermolecular proton exchange for 0.27, 0.59, and 0.79 M solutions of phenol in CCl4 are analyzed. The long-range coupling over five bonds between the hydroxyl and ring protons is estimated as 0.33 Hz in the monomer and as 0.20 Hz in the trimer of a monomer–trimer model. Support for the decrease in the coupling on trimerization is found in CNDO/2 and INDO MO FPT calculations. The long-range coupling over six bonds is unobservable, consistent with conformations of the trimer in which the phenol molecules remain planar. Water catalyzes the intermolecular proton exchange and, in its absence, the transfer of hydroxyl protons from molecule to molecule within the associated species is inefficient.

The analysis of the proton magnetic resonance spectra of heteroaromatic systems. V. Diazanaphthalenes

1965 ◽  
Vol 18 (5) ◽  
pp. 707 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan
Keyword(s):  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Direct Calculation ◽  
Coupling Constants ◽  
Dilute Solutions ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of the four isomeric diazanaphthalenes, quinoxaline, phthalazine, quinazoline, and cinnoline, all as dilute solutions in carbon tetrachloride and acetone, have been investigated at 100 Mc/s. The chemical shifts and coupling constants have been obtained by direct calculation or, where appropriate, by an iterative procedure. Long-range coupling constants between protons separated by five and six bonds have been observed.

Proton magnetic resonance spectra of indolizine and its methyl derivatives and aza analogues

1964 ◽  
Vol 17 (10) ◽  
pp. 1128 ◽  
Author(s):  
PJ Black ◽  
ML Heffernan ◽  
LM Jackman ◽  
QN Porter ◽  
GR Underwood
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Iterative Procedure ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Methyl Derivatives ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of indolizine, indolizine-1,3-d2, 1- and 2-methylindolizine, 2,3-, 2,5-, 2,6-, and 2,7-dimethylindolizine and 1-, 2-, and 3-azaindolizine have been determined at 100 and/or 60 Mc/s. Unequivocal assignments have been made to all protons and the coupling constants and chemical shifts for indolizine and its aza analogues have been obtained by an iterative procedure. Long-range coupling constants involving protons separated by five and six bonds have been observed.

Long-range coupling in the proton magnetic resonance spectra of 1,4-dihydrobenzenes

1965 ◽  
pp. 456 ◽  
Author(s):  
Lois J. Durham ◽  
J. Studebaker ◽  
M. J. Perkins
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Magnetic Resonance Spectra

Proton magnetic resonance studies of non-alternant hydrocarbons. I. Some comments on the aromatic character of the fulvenes

1966 ◽  
Vol 19 (10) ◽  
pp. 1813 ◽  
Author(s):  
ML Heffernan ◽  
AJ Jones
Keyword(s):  
Magnetic Resonance ◽  
High Resolution ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Magnetic Resonance Studies ◽  
Aromatic Character ◽  
Alternant Hydrocarbons ◽  
Cyclic Dienes ◽  
Magnetic Resonance Spectra

The high-resolution proton magnetic resonance spectra of 6- phenylfulvene, 6-methyl-6-phenylfulvene, and 6-dimethylaminofulvene have been studied in detail. The aromatic character of the fulvenes is discussed in terms of the derived parameters, and observations, in general, indicate that these compounds should be regarded as cyclic dienes. Long-range coupling constants involving protons separated by five and six bonds have been observed.

Proton magnetic resonance spectra of some β-methylstyrenes, β,β-dimethylstyrenes, and α-methylstilbenes; and a discussion of long-range shieldingand coupling effects in these and related systems

1965 ◽  
Vol 18 (11) ◽  
pp. 1759 ◽  
Author(s):  
H Rottendorf ◽  
S Sternhell ◽  
JR Wilmshurst
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Coupling Effects ◽  
Styrene Derivatives ◽  
Shielding Effects ◽  
Magnetic Resonance Spectra

The preparation of some new β,β-dimethylstyrenes and α-methylstilbenes is described and their p.m.r. spectra are reported. The long-range shielding effects in β,β-dimethylstyrenes and other styrene derivatives are discussed. The differences between the cisoid and transoid allylic coupling constants in β,β-dimethylstyrenes are much smaller than the corresponding differences in simple propenes. No appreciable (J ≥ 0.3 c/s) coupling between the non-equivalent methyl protons in β,β-dimethylstyrenes has been observed. Long-range coupling in the compounds investigated appears to be independent of ring substitution. Some general features of allylic coupling are discussed.

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