4-Amino-1-(2, 3-dideoxy-β-D-glycero-pentofuranosyl)-1H-pyrazolo [3, 4-d] pyrimidine (5) was synthesized from 8-aza-7-deaza-2'-deoxyadenosine (1). Benzoylation of the 4-amino group of 1 followed by 4, 4'-dimethoxytritylation of the 5'-hydroxyl function gave 2b. Barton deoxygenation of the phenoxythiocarbonyl compound 3 afforded 4a and yielded 5 after removal of the protecting groups. The N-glycosylic bond stability of 5 to acid was higher than that of 2', 3'-dideoxyadenosine (ddA). Compound 5 showed no appreciable activity against human immunodeficiency virus. It was converted into allopurinol 2', 3'-dideoxyribofuranoside (6) by adenosine deaminase but at a lower rate than the conversion of ddA into ddl.