Conformational analysis of natural products
Hetero- and homonuclear coupling constant calculation
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Hetero- and homonuclear coupling constant calculation
Conformational analysis
Introduction
Coupling constants
3
J
H,H
Haasnoot
3
J
H,H
Pachler
Heteronuclear J
Chemical shifts
Electronegativity
Alkenes
Alkynes
Allenes
Benzenes
Pyridines
Furanes
Thiophenes
Pyrroles
Aldehydes
Esters
Amides
Carbohydrates
13
C chemical shifts
Coupling constants
Hydroxymethyl
C5-C6-rotamers
C5-C6-rotamers, derivatives
Nucleosides
Nucleotides
J
CH
in 2-deoxyribose
Couplings in ribofuranose
Couplings in furanoses
Equation
3
J
=1.8*cos
2
(θ)-0.2*cos(θ)+0.5
Coupling constant calculation
Karplus-type equations are frequently used to relate vicinal coupling constants, i. e.
3
J
, to torsion angles. To calculate a coupling constant for a given dihedral angle (θ) enter a value in the form and press
Calculate
.
To calculate a torsion angle from a coupling constant enter the coupling constant in the
3
J
field press
Calculate
. There may be up to four solutions.
The results are shown below!
Torsion angle (θ):
°
Coupling constant (
3
J
):
Hz