The experimental values of the 3JH5,H6 [1] are interpreted using two
different sets of limiting values.
The values of Bock and Duus [1] are based on the Karplus equation of Haasnoot et al. [2] whereas those of Stenutz et al.
[3] are based on quantum mechanical calculations in 2-hydroxymethyl tetrahydropyran (oxane).
Apart from slight differences in the relationship between torsion angles and coupling constants
Stenutz et al. assume a larger torsion (65°) for the gg and gt rotamers.
The θ torsion is defined here as C5-C6-O6-X, i.e. H or glycosyl/alkyl.
The amount of trans can be estimated from 2JH6R,H6S
if the amounts of the ω rotamers are known.
The ω rotamers are estimated to be accurate to about +-5%, but the error in
θ is larger since 1) the relationship between 2JH6R,H6S
is less reliable and 2) the ω rotamer populations are required. An error of at
least +-10% is to be expected.
[1] K. Bock and J.Ø. Duus,
J. Carbohydr. Chem. 13 (1994) 513-543
[2] C.A.G. Haasnoot, F.A.A.M. DeLeeuw and C. Altona,
Tetrahedron 36 (1980) 2783-2792.
[3] R. Stenutz, I. Carmichael, G. Widmalm and A.S. Serianni,
J. Org. Chem. 67 (2002) 949-958
DOI 10.1021/jo010985i
Hydroxymethyl coupling constants and rotamer distribution in hexopyranoses
|
Coupling constants |
Bock & Duus |
Stenutz et al. |
| Compound |
3JH5,H6R |
3JH5,H6S |
2JH6R,H6S |
Pgt |
Pgg |
Ptg |
Pgt |
Pgg |
Ptg |
θtrans |
| methyl α-D-glucopyranoside
[97-30-3] | 5.49 | 2.39 | -12.35 |
50 | 57 | -7 |
47 | 42 | 10 |
7 |
| methyl α-D-glucopyranoside (CD3OD)
[97-30-3] | 5.64 | 2.40 | -11.80 |
51 | 56 | -7 |
49 | 41 | 11 |
26 |
| methyl β-D-glucopyranoside
[7000-27-3] | 6.11 | 2.47 | -12.31 |
56 | 50 | -6 |
54 | 35 | 11 |
9 |
| α-D-glucopyranose (DMSO)
[9050-36-6] | 5.00 | 2.30 | -11.20 |
45 | 63 | -8 |
42 | 48 | 10 |
46 |
| β-D-glucopyranose
[921-60-8] | 5.78 | 2.29 | -12.33 |
53 | 55 | -8 |
51 | 40 | 9 |
9 |
| β-D-glucopyranose (DMSO)
[921-60-8] | 5.90 | 2.20 | -11.80 |
55 | 55 | -10 |
53 | 39 | 8 |
27 |
| methyl α-D-mannopyranoside
| 6.40 | 2.44 | -12.20 |
59 | 48 | -7 |
57 | 32 | 11 |
12 |
| methyl 2-acetamido-2-deoxy-β-D-glucopyranoside
| 5.38 | 2.35 | -12.20 |
49 | 59 | -8 |
46 | 44 | 10 |
13 |
| 6-O-methyl-α-D-glucopyranose
| 5.73 | 2.37 | -11.04 |
52 | 55 | -7 |
50 | 40 | 10 |
51 |
| 6-O-methyl-β-D-glucopyranose
| 6.10 | 2.16 | -11.20 |
57 | 53 | -10 |
55 | 37 | 8 |
47 |
| 4,6-di-O-methyl-β-D-glucopyranose
| 5.64 | 1.96 | -11.14 |
54 | 59 | -13 |
51 | 43 | 6 |
50 |
| methyl 6-O-acetyl-β-D-glucopyranoside
| 4.90 | 2.30 | -12.30 |
44 | 64 | -8 |
41 | 49 | 10 |
9 |
| methyl 4,6-di-O-acetyl-β-D-glucopyranoside
| 3.80 | 2.10 | -12.60 |
34 | 76 | -10 |
30 | 62 | 8 |
0 |
| methyl 6-O-phosphono-α-D-glucopyranoside (pH 1.3)
| 4.60 | 2.40 | -11.60 |
41 | 66 | -7 |
37 | 52 | 11 |
32 |
| methyl 6-O-phosphonato-α-D-glucopyranoside (pH 9.3)
| 3.53 | 1.91 | -12.13 |
32 | 80 | -12 |
28 | 67 | 6 |
17 |
| methyl 4-deoxy-α-D-xylo-hexopyranoside
| 6.20 | 3.03 | -12.06 |
54 | 45 | 1 |
52 | 31 | 17 |
14 |
| methyl 4-deoxy-β-D-xylo-hexopyranoside
| 7.42 | 3.34 | -12.04 |
65 | 31 | 4 |
65 | 15 | 20 |
14 |
| methyl 4-O-acetyl-β-D-glucopyranoside
| 5.90 | 2.20 | -12.30 |
55 | 55 | -10 |
53 | 39 | 8 |
10 |
| methyl 4,4-di-hydroxy-α-D-xylo-hexopyranoside
| 8.40 | 2.40 | -12.00 |
80 | 28 | -8 |
79 | 11 | 10 |
19 |
| methyl 4-thio-α-D-glucopyranoside
| 5.00 | 2.00 | -12.50 |
47 | 65 | -12 |
44 | 50 | 6 |
4 |
| methyl 4-ammonio-4-deoxy-α-D-glucopyranoside (pH 2.0)
| 4.64 | 3.70 | -12.44 |
34 | 56 | 10 |
32 | 43 | 25 |
-1 |
| methyl 4-amino-4-deoxy-α-D-glucopyranoside (pH 9.0)
| 5.40 | 2.46 | -12.42 |
48 | 58 | -6 |
46 | 43 | 11 |
5 |
| C-propyl β-D-glucopyranoside
| 8.50 | 2.40 | |
81 | 27 | -8 |
81 | 10 | 10 |
| methyl α-D-galactopyranoside
| 8.60 | 3.70 | -11.70 |
75 | 16 | 9 |
76 | 0 | 24 |
24 |
| methyl β-D-galactopyranoside
[1824-94-8] | 7.50 | 4.83 | -11.76 |
58 | 19 | 24 |
59 | 5 | 36 |
17 |
| β-D-galactopyranose
| 7.92 | 4.28 | -11.50 |
65 | 19 | 16 |
66 | 4 | 30 |
28 |
|
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