Viswamitra, M.A. & Gautham, N. Proc. Indian Acad. Sci. (Chem. Sci.) (1984) 93: 261. doi:10.1007/BF02840518
Crystal structures of six isopropylidene nucleoside derivatives are described. The results show that, under external cyclic constraints, the ribose assumes a variety of unusual conformations. In those compounds which possess a base-to-sugar cyclization through the C(4′) atom, the furanose pucker is predominantly C(4′)-endo, O(4′)-exo. The possible relevance of the sulphur geometry in two of the compounds to certain structural aspects of the action of the enzyme thymidylate synthetase is also pointed out.
Crystal structureisopropylidene nucleoside derivativesribose ring flexibilitysulphur geometryexternal cyclization