Abstract
Synthesis of hexofuranosyluracil cyclonucleosides carbon-bridged between C-6 and C-6'is described. Treatment of 6-cyano-5'-iodo-2', 3'-O-isopropylidene-5'-deoxyuridine with tri-n-butyltin hydride and 2, 2'-azobisisobutyronitrile gave the 6'-imino-6, 6'-cyclo-5', 6'-dideoxyallofuranosyluracil, which was converted to the 6'-oxo derivative. The 6'-oxo function was reduced with sodium borohydride and the 6'-hydroxyl group was eliminated to give the 5', 6'-unsaturated cyclodideoxyallofuranosyluracil, which was hydrogenated to furnish 6, 6'-cyclo-5', 6'-dideoxyallofuranosyluracil, a uridine derivative fixed in the anti form.
