Pseudorotation of furanoses

The pseudorotation of furanoses, in particular ribofuranoses, is often described in terms of pseudorotation angles (P) and puckering (ν_max). The endocyclic torsions (ν) can be approximated using the relationship derived by Altona and Sundaralingam [1].

ν_i=P*cos(ν_max+(i-2)*4*π/5)

Using the torsions ν₀-ν₄ the torsions between the ring protons can be derived. Together with an appropriate Karplus equation[2] the corresponding coupling constants can be estimated, or experimental coupling constants can be used to determine the phase (P) and puckering (ν_max) of the ring.

Literature

[1] C. Altona and M. Sundaralingam; J. Am. Chem. Soc. 94 (1972) 8205-8212.
[2] C.A.G. Haasnoot, F.A.A.M. DeLeeuw and C. Altona; Tetrahedron 36 (1980) 2783-2792.

Instructions

Choose the correct substituents for positions C1'-C3' (or equivalent, e.g. C2,C3,C4 in fructofuranose).
Choose the correct stereochemistry either by specifying the orientation of each substituent (check if below the plane of the ring) or select from ribo, arabino, &c below.
Enter coupling constants if known.