Laccase-catalyzed phenol oxidation. Rapid assignment of ring-proton deficient polycyclic benzofuran regioisomers by experimental 1H–13C long-range coupling constants and DFT-predicted product formation

2011 ◽  
Vol 9 (8) ◽  
pp. 2667 ◽  
Author(s):  
Heiko Leutbecher ◽  
Gerhard Greiner ◽  
Robert Amann ◽  
Andreas Stolz ◽  
Uwe Beifuss ◽  
...  
Keyword(s):  
Long Range ◽  
Product Formation ◽  
Coupling Constants ◽  
Phenol Oxidation ◽  
Ring Proton

scholarly journals Six-bond 1H,1H and 1H,19F spin coupling constants as indicators of geometry in aniline and p-fluoroaniline

1985 ◽  
Vol 63 (8) ◽  
pp. 2253-2255 ◽  
Author(s):  
Ted Schaefer ◽  
Glenn H. Penner
Keyword(s):  
Long Range ◽  
Benzene Solution ◽  
Far Infrared ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Amino Group ◽  
Fluorine Nucleus ◽  
Ring Proton ◽  
Spin Coupling Constants ◽  
Infrared Data

The long-range coupling constants between amino protons and the ring proton or fluorine nucleus in the para position of aniline and p-fluoroaniline imply that, in benzene solution, the geometry at the amino group is very similar in the two compounds. The ratio of the two coupling constants is consistent with potential functions for inversion at nitrogen derived from far infrared data, but inconsistent with microwave spectra which indicate that the angle defining the intersection of the amino and benzene planes differs by 9° in these two compounds.

Signs of long-range amino proton – ring proton coupling constants in N-ethyl-4-chloro-2-nitroaniline

1970 ◽  
Vol 48 (8) ◽  
pp. 1343-1345 ◽  
Author(s):  
T. Schaefer ◽  
R. Wasylishen
Keyword(s):  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Proton Resonance ◽  
Ring Proton ◽  
Multiple Resonance ◽  
Proton Coupling ◽  
Spin Spin Coupling

In N-ethyl-4-chloro-2-nitroaniline there exists a measurable indirect spin–spin coupling constant of ±0.39 ± 0.03 Hz between the methylene protons and ring proton 6. The amino proton is coupled to ring protons 5 and 6 and also to the methylene protons. Consequently, although the amino proton resonance is broad due to incompletely relaxed coupling to 14N, normal multiple resonance experiments show that 5JmH,NH = 0.67 ± 0.03 Hz and 4JoH,NH = −0.35 ± 0.03 Hz.

How to measure long-range proton-carbon coupling constants from 1 H-selective HSQMBC experiments

2019 ◽  
Vol 58 (5) ◽  
pp. 363-375 ◽  
Author(s):  
Josep Saurí ◽  
Pau Nolis ◽  
Teodor Parella
Keyword(s):  
Long Range ◽  
Coupling Constants

Strongly hindered rotation in α,α,2,6-terrachlorotoluene. Stereospecific five-bond coupling. Hyperconjugative contributions to long-range sidechain-ring proton coupling constants

1968 ◽  
Vol 46 (12) ◽  
pp. 2187-2188 ◽  
Author(s):  
T. Schaefer ◽  
R. Schwenk ◽  
C. J. Macdonald ◽  
W. F. Reynolds
Keyword(s):  
Free Energy ◽  
Resonance Spectrum ◽  
Coupling Constants ◽  
Proton Resonance ◽  
Kcal Mole ◽  
Hindered Rotation ◽  
Ring Proton ◽  
Meta Position ◽  
Proton Coupling ◽  
Free Energy Of Activation

At −40 °C the C—H bond of the dichloromethyl group of α,α,2,6-tetrachlorotoluene lies in the plane of the ring. The proton resonance spectrum demonstrates a stereospecific five-bond coupling between the C—H proton and the ring proton in the meta position. The coupling to the para proton is essentially zero as expected from a hyperconjugative mechanism. The free energy of activation of rotation of the dichloromethyl group is about 15 kcal/mole at 25 °C.

Measurement of long-range heteronuclear coupling constants

1989 ◽  
Vol 85 (1) ◽  
pp. 111-131 ◽  
Author(s):  
Jeremy J Titman ◽  
David Neuhaus ◽  
James Keeler
Keyword(s):  
Long Range ◽  
Coupling Constants ◽  
Heteronuclear Coupling

scholarly journals Signs of proton–proton and proton–fluorine spin–spin coupling constants in 2-fluoro-3-methylpyridine. Sigma and pi contributions to coupling in a nitrogen heterocycle

1969 ◽  
Vol 47 (9) ◽  
pp. 1507-1514 ◽  
Author(s):  
T. Schaefer ◽  
S. S. Danyluk ◽  
C. L. Bell
Keyword(s):  
Nitrogen Atom ◽  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nitrogen Heterocycle ◽  
Triple Resonance ◽  
Triple Resonance Experiments ◽  
Proton Proton ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The signs of all proton–proton and proton–fluorine spin–spin coupling constants in 2-fluoro-3-methylpyridine have been determined by double and triple resonance experiments. The signs of the longrange coupling constants, JH,CH3 and JF,CH3 are the same as in fluorotoluene derivatives. Their magnitudes are consistent with the assumption that the nitrogen atom primarily polarizes the σ bonds in the molecule, leaving the π contribution to the long-range coupling relatively unaffected.

Sign in / Sign up

Export Citation Format

Share Document