Synthesis of l-ribofuranosyl C-nucleosides

C-Nucleosides, 4-amino-8-(β- l -ribofuranosyl)pyrazolo[1,5-a]-1,3,5-triazine ( 12 ) and 4-amino-7-(β- l -ribofuranosyl)-5H-pyrrolo[3,2-d]pyrimidine ( l -9-deazaadenosine, 22 ), were synthesized from the key intermediate, 3-dimethylamino-2-(2,3-O-isopropylidene-5-O-trityl- l -ribofuranosyl)acrylonitrile ( 8 ), which was prepared from l -xylose in 11 steps.