ZZB zzb [(1S,3S,5R,6R,8R)-6-(6-AMINOPURIN-9-YL)-4'-ETHYLAMINO-3'-FLUORO-SPIRO[2,4,7-TRIOXA-3-BORANUIDABICYCLO[3.3.0]OCTANE-3,7'-8-OXA-7-BORANUIDABICYCLO[4.3.0]NONA-1,3,5-TRIENE]-8-YL]METHYL DIHYDROGEN PHOSPHATE ZZB