Synthesis and biological activity of 2 '-fluoro-D-arabinofuranosylpyrazolo[3,4-d]pyrimidine nucleosides

Coupling of 2-fluoro-3,5-di-O-benzoyl-alpha-D-arabinofuranosyl bromide with 4-methoxypyrazolo[3,4-d]pyrimidine gave an alpha-D/beta-D mixture of N-1- and N-2-coupled products. All the anomers were separated and deblocked to y ield the corresponding nucleosides. The beta-D-anomer 7 was converted to th e 4-amino derivative 11, which was deaminated by adenosine deaminase to giv e the 4-oxo compound 12. Compound 7 showed significant activity against hum an cytomegalovirus and hepatitis B virus, and compound 11 showed activity a gainst human herpes virus 8. All the compounds were noncytotoxic in several human tumor-cell lines in culture.