N′-[3-Cyano-1-(2-deoxy-β-D-erythro-pentofuranosyl)-4,5-dihydro-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-N,N-dimethylmethanimidamide

N′-[1-(2-Deoxy-β-D-erythro-pentofuranosyl)-4,5-dihydro-3-iodo-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-N,N-dimethylmethanimidamide

N′-[3-Bromo-1-(2-deoxy-β-D-erythro-pentofuranosyl)-4,5-dihydro-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-N,N-dimethylmethanimidamide

N-[1-[5-O-[Bis(4-methoxyphenyl)phenylmethyl]-2-deoxy-β-D-erythro-pentofuranosyl]-3-(1-hexyn-1-yl)-4,5-dihydro-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-2-methylpropanamide

N-[1-(2-Deoxy-β-D-erythro-pentofuranosyl)-3-(1-hexyn-1-yl)-4,5-dihydro-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-2-methylpropanamide

6-Amino-1-(2-deoxy-β-D-erythro-pentofuranosyl)-1,5-dihydro-3-(4-hydroxy-1-butyn-1-yl)-4H-pyrazolo[3,4-d]pyrimidin-4-one

6-Amino-1-(2-deoxy-β-D-erythro-pentofuranosyl)-3-(1-heptyn-1-yl)-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one

N-[1-[5-O-[Bis(4-methoxyphenyl)phenylmethyl]-3-O-[[bis(1-methylethyl)amino](2-cyanoethoxy)phosphino]-2-deoxy-β-D-erythro-pentofuranosyl]-3-(1-hexyn-1-yl)-4,5-dihydro-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-6-yl]-2-methylpropanamide