6-Amino-3,9-dihydro-9-(5-O-phosphono-β-D-arabinofuranosyl)-2H-purin-2-one is derived from Methyl 2,3,5-Tri-O-benzoyl-α-D-arabinofuranoside (M330830), which is used in the preparation of 1-α- and 1-β-D-Arabinofuranosyl-2-nitroimidazole (α-AZA and β-AZA) as synthons for a number of potential markers of tissue hypoxia.