NUCLEOSIDES .50. STRUCTURE OF LUMAZINE N1-(2'-DEOXY-D-RIBONUCLEOSIDES) (= 1-(2'-DEOXY-D-RIBOFURANOSYL)PTERIDINE-2,4(1H,3H)-DIONES) - A REVISION OF THE ANOMERIC CONFIGURATION

The anomeric configuration of the glycosidic bond in lumazine N1-(2'-deoxy-D-ribonucleosides) 1-6 was investigated by NOE difference spectroscopy. The former configurational assignment of the alpha- and beta-D-anomers 1 and 2, 3 and 4, and 5 and 6, respectively, has to be reversed to be in agreement with the physical data. Additional proof is presented by X-ray analysis of 3 and 6. Chemical interconversions of 1-(2'-deoxy-beta-D-ribofuranosyl)-6,7-diphenyllumazine (6) into 2,3'-anhydrolumazine 2'-deoxyribonucleosides 16 and 17 are also in agreement with the revised anomeric configuration.