4
1
General Principles
Keywords
Conformation; Chair; Anomeric effect; Hydroxymethyl; Monosaccharides; Disaccharides;
Oligosaccharides; Coupling constants; Molecular mechanics; Molecular dynamics
Abbreviations
A-value free energy cost for a substituent on a chair conformation of a cyclohexane ring
to change from an equatorial to axial orientation
B
boat
B3LYP the Becke-3 Lee–Yang–Parr density functional
C
chair
CD
circular dichroism
DFT
density functional theory
E
envelope conformation of a five-membered ring
G
Gaussian
gg, gt, tg conformations of hydroxymethyl or other side-chains on pyranose or furanose rings
GVB
generalized valence bond
H
half chair
HOMO highest energy occupied molecular orbital
KDO
3-deoxy-D-manno-2-octulosonic acid
MP
Moeller–Plesset
NANA 5-acetamido-3,5-dideoxy-D-glycero-D-galacto-2-nonulosonic acid
nOe
nuclear Overhauser enhancement
ORD
optical rotatory dispersion
ROA
resonant Raman optical activity
S
skew conformation of a six-membered ring
T
twist conformation of a five-membered ring
TB
twist boat
TC
twist chair
1 Conformational Analysis
1.1 Introduction
The shapes or conformations of carbohydrates strongly influence both their reactivity and their
physical properties. Several reviews of various aspects of the conformational analysis of carbohydrates have been published [1,2,3,4,5,6,7].
Monosaccharides exist chiefly in the six-membered pyranose form and in the five-membered
furanose form, both of which adopt puckered shapes to minimize eclipsing interactions.
These puckered shapes are most commonly described in terms of the shapes of the symmetrical conformations adopted by the analogous hydrocarbons, cyclohexane and cyclopentane [8,9,10,11], but may also be described in terms of puckering parameters [12,13,14].
Minima on the conformational potential energy surface are called conformers.
1
General Principles
Keywords
Conformation; Chair; Anomeric effect; Hydroxymethyl; Monosaccharides; Disaccharides;
Oligosaccharides; Coupling constants; Molecular mechanics; Molecular dynamics
Abbreviations
A-value free energy cost for a substituent on a chair conformation of a cyclohexane ring
to change from an equatorial to axial orientation
B
boat
B3LYP the Becke-3 Lee–Yang–Parr density functional
C
chair
CD
circular dichroism
DFT
density functional theory
E
envelope conformation of a five-membered ring
G
Gaussian
gg, gt, tg conformations of hydroxymethyl or other side-chains on pyranose or furanose rings
GVB
generalized valence bond
H
half chair
HOMO highest energy occupied molecular orbital
KDO
3-deoxy-D-manno-2-octulosonic acid
MP
Moeller–Plesset
NANA 5-acetamido-3,5-dideoxy-D-glycero-D-galacto-2-nonulosonic acid
nOe
nuclear Overhauser enhancement
ORD
optical rotatory dispersion
ROA
resonant Raman optical activity
S
skew conformation of a six-membered ring
T
twist conformation of a five-membered ring
TB
twist boat
TC
twist chair
1 Conformational Analysis
1.1 Introduction
The shapes or conformations of carbohydrates strongly influence both their reactivity and their
physical properties. Several reviews of various aspects of the conformational analysis of carbohydrates have been published [1,2,3,4,5,6,7].
Monosaccharides exist chiefly in the six-membered pyranose form and in the five-membered
furanose form, both of which adopt puckered shapes to minimize eclipsing interactions.
These puckered shapes are most commonly described in terms of the shapes of the symmetrical conformations adopted by the analogous hydrocarbons, cyclohexane and cyclopentane [8,9,10,11], but may also be described in terms of puckering parameters [12,13,14].
Minima on the conformational potential energy surface are called conformers.