111375-45-2 4H-Pyrazolo[3,4-d]pyrimidin-4-one, 6-amino-1,5-dihydro-3-methoxy-1-.beta.-D-ribofuranosyl- 6-Amino-3-methoxy-1-.beta.-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one AIDS-001496 AIDS001496 Pyrazolopyrimidine nucleoside