55648-40-3 9-.beta.-D-Arabinofuranosyladenine 5'-formate 9.beta.-D-Arabinofuranoxyladenine 5'-formate 9H-Purin-6-amine, 9-(5-O-formyl-.beta.-D-arabinofuranosyl)- Arabinosyladenine 5'-O-formate ester NSC 171240 NSC171240