Flavan derivatives. XVI. Acid-catalysed reactions of secondary benzyl alcohols and 1-tetralols in methanol

1967 ◽  
Vol 20 (10) ◽  
pp. 2137 ◽  
Author(s):  
JW Clark-Lewis ◽  
V Nair
Keyword(s):  
Acetic Acid ◽  
Hydrogen Chloride ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Dibenzyl Ether ◽  
Proton Coupling ◽  
Spin Coupling Constants ◽  
Acid Catalysed Reactions ◽  
Cis And Trans ◽  
Spin Spin Coupling

Under solvolytic conditions I-phenylpropan-1-01 and its p-methyl and p-methoxy derivatives gave 1 -arylprop- 1 -enes. 1 -(3,4-Dimethoxypheny1)propan- 1-01 behaved similarly, but in addition gave the known propene dimer di-isohomogenol (di-isoeugenol dimethyl ether). Ring-proton coupling constants (J 7.3 and 9.2 CIS) appear consistent with a staggered trans-trans-configuration for this dimer,$ in agreement with earlier interpretations of chemical evidence. 1-(2,4,6-Trimethoxy- pheny1)propan-1-01 proved very reactive and gave the symmetrical dibenzyl ether under very mild acid catalysis, but with higher acid concentration it gave the prop-1-ene accompanied by a 1,l-diarylpropane formed by electrophilic displace- ment of the propan-1-01 side-chain. Tetralin-1-01 and cis- and trans-tetralin-1,2-diols, which lack activating aromatic substituents, were stable towards methanolic acetic acid (3%) or hydrogen chloride (3%). 6-Methoxytetralin-1-01, however, gave 1,6-dimethoxytetralin with methanolic 0.001% acetic acid, but with higher tetra101 concentration it gave the symmetrical bis-tetralyl ether. 6-Methoxytetralin-1-01 gave 3,4-dihydro-6-methoxynaphthalene and its known dimer when heated with methanolic hydrogen chloride (1%). Nuclear magnetic resonance showed that the tetralins are conformationally mobile, and the spectra were consistent with rapid interconversion of two half-chair conformations. 3-Phenyltetralin-1-01 (tetralin analogue of flavan-3-01) was obtained in the l,3-cis-form and existed in the confor- mationally stable half-chair form with both substituents equatorial. Spin-spin coupling constants of cis- and trans-carbonates of tetralin-1,2-diols are close to values recorded for their flavandiol analogues.

The Molecular Structure of Allenes and Ketenes, XIII Correlations of Carbon-Proton Spin-Spin Coupling Constants in Allenes with ab initio STO-3G Overlap Populations

1979 ◽  
Vol 34 (1) ◽  
pp. 118-120 ◽  
Author(s):  
Wolfgang Runge
Keyword(s):  
Molecular Structure ◽  
Ab Initio ◽  
Substituent Effects ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Proton Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Cl Atoms

Abstract It is shown that substituent effects on one-bond and long-range carbon-proton coupling constants in monosubstituted allenes parallel quantitatively ab initio STO-3G carbon 2s-hydrogen 1 s overlap populations, irrespectively of whether the substituents are bonded to the allenic skeleton via first-row (C, O) or second-row (Si, S, Cl) atoms.

199Hg-1H Spin-spin coupling in vinyl and ethynyl mercurials

1964 ◽  
Vol 17 (11) ◽  
pp. 1204 ◽  
Author(s):  
PR Wells ◽  
W Kitching
Keyword(s):  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Cis And Trans ◽  
Spin Spin Coupling

The proton magnetic spectra of cis and trans-2-chlorovinylmercuric chloride, bis(trans-2-chlorovinyl)mercury, and methylethynylmercury have been determined. Large variations in the 199Hg-1H spin-spin coupling constants are observed for different hybridization states and different geometries.

Information from stereospecific spin–spin couplings about the relative absorptivities of the hydroxyl stretching bands in 2-iodophenol solutions

1981 ◽  
Vol 59 (21) ◽  
pp. 3021-3025 ◽  
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian ◽  
Timothy A. Wildman
Keyword(s):  
Free Energy ◽  
Molecular Orbital ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Calculations ◽  
Temperature Dependent ◽  
Hydroxyl Proton ◽  
Spin Coupling Constants ◽  
Cis And Trans ◽  
Spin Spin Coupling

The stereospecific spin–spin coupling constants between the hydroxyl proton and the ring protons for 2-iodophenol in various solvents yield some free energy differences between the cis and trans conformations of this molecule at 305 K. Comparison with areas of the hydroxyl stretching bands in the same or similar solvents shows that the ratio of the absorptivity coefficients for the two conformers is sensitive to solvent. It is suggested that this ratio is temperature dependent and therefore apparent enthalpy differences must be considered tentative for at least some solutions. Molecular orbital calculations are consistent with the arguments concerning the absorptivity coefficients.

ChemInform Abstract: NITROGEN-15-CARBON-13 SPIN-SPIN COUPLING CONSTANTS OF CIS- AND TRANS-1-ALKYL-2-ARYL-3-BENZOYLAZIRIDINES

1979 ◽  
Vol 10 (42) ◽  
Author(s):  
P. TARBURTON ◽  
J. P. EDASERY ◽  
C. A. KINGSBURY ◽  
A. E. SOPCHIK ◽  
N. H. CROMWELL
Keyword(s):  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Cis And Trans ◽  
Spin Spin Coupling

Nuclear magnetic resonance study of carbethoxypyrroles

1970 ◽  
Vol 48 (14) ◽  
pp. 2303-2305 ◽  
Author(s):  
M. W. Roomi ◽  
H. Dugas
Keyword(s):  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Ring Proton ◽  
Proton Coupling ◽  
Low Field ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The chemical shifts and the ring proton coupling constants of various substituted carbethoxypyrroles are reported.The electron-withdrawing effect of the carbethoxy groups shifts the resonances of the ring substituents to low field while the inductive and mesomeric effects of the methyl groups shift the resonances to higher field. The deshielding effect is more pronounced with 2-carbethoxypyrroles than for 3-carbethoxypyrroles. The ring proton spin–spin coupling constants depend on the nature of substituents and increase with the electronegativity of the substituents. In some cases long-range coupling between the methyl side-chain protons and ring protons could be observed.

Nitrogen-15-carbon-13 spin-spin coupling constants of cis- and trans-1-alkyl-2-aryl-3-benzoylaziridines

1979 ◽  
Vol 44 (12) ◽  
pp. 2041-2042 ◽  
Author(s):  
Philip Tarburton ◽  
James P. Edasery ◽  
Charles A. Kingsbury ◽  
Alan E. Sopchik ◽  
Norman H. Cromwell
Keyword(s):  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Cis And Trans ◽  
Spin Spin Coupling

The Proton–Proton and Proton–Carbon-13 Spin–Spin Coupling Constants in 1,3-Dioxole and Bis-1,3-dioxolyl. Conformational Dependence

1975 ◽  
Vol 53 (18) ◽  
pp. 2734-2741 ◽  
Author(s):  
Ted Schaefer ◽  
Kalvin Chum ◽  
David McKinnon ◽  
M. S. Chauhan
Keyword(s):  
Double Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Dihedral Angles ◽  
Proton Proton ◽  
Proton Coupling ◽  
Vicinal Proton ◽  
Karplus Relationship ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The carbon-13 satellite peaks in the proton magnetic resonance spectra of 1,3-dioxole and bis-1,3-dioxolyl are analyzed under single and double resonance conditions to yield the signs and magnitudes of proton–proton coupling constants over three, four, and five bonds, and of proton–carbon-13 coupling constants over one, two, and three bonds. The conformational behavior of bis-1,3-dioxolyl contrasts sharply with that of analogous sym-tetrasubstituted ethane derivatives. It is indicated that the two-bond proton–carbon-13 coupling in the ethanic fragment can be used for conformational analysis in a manner similar to vicinal proton–proton couplings. The vicinal three-bond proton–carbon-13 couplings are given for dihedral angles of 180 and 120° and their relative magnitudes are as expected from a Karplus relationship. The two-bond proton–carbon-13 coupling in the olefinic fragment is, at 20.0 Hz, the largest coupling known for such a bond.

Long-range spin–spin coupling constants between ring protons and aldehydic protons in some para-substituted benzaldehydes

1969 ◽  
Vol 47 (21) ◽  
pp. 4005-4010 ◽  
Author(s):  
S. S. Danyluk ◽  
C. L. Bell ◽  
T. Schaefer
Keyword(s):  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Proton Proton ◽  
Proton Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Coupling Mechanisms ◽  
Benzaldehyde Derivatives

The long-range proton–proton coupling constants between the ring protons and the aldehydic proton are reported for a series of para-substituted benzaldehyde derivatives. It was found that JoH,CHO < 0 and JmH,CHO > 0. Furthermore, JoH,CHO increases in magnitude as the electron donating power of the sub-stituent increases. A similar trend is observed forJmH,CHO but the ratio of the increase to the magnitude of JmH,CHO is much less than for JoH,CHO. A good correlation is obtained between JoH,CHO and the sub-stituent parameters of Swain and Lupton.The coupling constant data are discussed in terms of σ and π coupling mechanisms and it is concluded that σ electron mechanisms are dominant for both JoH,CHO and JmH,CHO.

Sign in / Sign up

Export Citation Format

Share Document