A (13)C-N.M.R. INVESTIGATION OF GLYCOSYL AZIDES AND OTHER AZIDO SUGARS: STEREOCHEMICAL INFLUENCES ON THE ONE-BOND (13)C-(1)H COUPLING CONSTANTS

Article abstract of DOI:10.1016/S0008-6215(00)90692-X

Unambigous (13)C assignments have been obtained, using 2D-n.m.r. techniques, for several glycosyl azides, 6-deoxyglucosyl azides, 2-acylamino-2-deoxyglycosyl azide, and some 2- and 3-azido monosaccharide derivatives.For non-anomeric C-H-bonds the ¹J_C,Heq. values are 4-9 Hz larger than the ¹J_C,Hαx. values.A substituent (hydroxyl, acetoxyl, alkoxyl, azido, etc.) in 1,3-diaxial relationship with Hax. significantly increases the value of ¹J_C,Hαx..Bond-angle distortions in the fused-ring bicyclic systems of some isopropylidene derivatives result in ¹J_C,Hαx. values being larger than ¹J_C,Heq. values.Electronic and stericeffects of substituents at non-anomeric carbons may alter the ¹J_C,H values for anomeric carbons to such an extent that they may no longer be useful for diagnosing anomeric configuration.Bond-angle deformations also influence the (13)C chemical shift differences in α- and β-anomers at C-5 and, to a lesser extent, at C-3.