Conformational analysis of β-D-ribo-, β-D-deoxyribo-, β-D-arabino-, β-D-xylo-, and β-D-lyxo-nucleosides from proton–proton coupling constants

摘要: A new n.m.r. coupling constant torsion angle relation is utilized to explore the effect of exocyclic oxygen substituents at C-2′ and C-3′ on J1′2.′, J2′,3′, J3′,4′ in furanose ring β-D-ribo-, β-D-arabino-, β-D-xylo-, β-D-lyxonucleosides. The five vicinal couplings β-D-deoxyribonucleosides are also investigated. Calculated constants for full pseudorotational itinerary different values puckering amplitudes given. It shown that experimental constants, taken from literature, can be satisfactorily explained all cases basis a two-state (N/S)-model pseudorotation. Good estimates both N- S- geometry conformational equilibrium five-membered rings ribose, deoxyribose, xylose, lyxose, arabinose derivatives judicious use geometrical information obtained by X-ray crystallographic studies appeared indispensable this type analysis.