Conformational Variability in Modified Nucleosides. Crystal and Molecular Structure of 2′,3′-O-Isopropylidene Inosine

Abstract

The crystal structure of 2′,3′-O-isopropylidene inosine shows a number of interesting features. The four independent molecules in the asymmetric unit exhibit significant conformational variations. Ribose puckers fall in the O(4′)-exo region, unfavourable in unsubstituted nucleosides. Hypoxanthine bases show base-pairing (I.I) in a manner analogous to the guanine self pairs (G.G) in 2′,3′-O-isopropylidene guanosine but with a C(2)-H…O(6) hydrogen bond instead of N(2)-H…O(6).