Unsaturated acyclic analogues of 2'-deoxyadenosine and thymidine containing fluorine: synthesis and biological...

The syntheses and biological activities of fluorobutynol 11 and (E)- and (Z)-fluorobutenols 8a,d and 9a,d are described. Alkylation of adenine with bromofluorobutyne 13a afforded intermediate 14 which was converted to fluorobutynol 11. Aldehyde 16a and (carbethoxyfluoromethyl)-triphenylphosphonium bromide furnished (E)- and (Z)-fluorobutenoates 19a and 20a accompanied by regioisomer 21a. A similar reaction of compound 16d afforded Z- and E-esters 19d and 20d. Reduction of the mixture of 19a and 20a with DIBALH gave (E)- and (Z)-fluoroalkenols 8a and 9a. Similarly, the Z-ester 19d gave (Z)-fluoroalkenol 9d. Both 19d and 20d were reduced with NaBH4 to give (Z)- and (E)-fluoroalkenols 9d and 8d. Hydrogenation of 19a and 20a afforded fluoro ester 23. A similar reduction of 8a and 9a led to fluoro alcohol 24 and the defluorinated product 25 which were separated by chromatography on a Bio-Rad AG 1-X2 (OH-) column. (Z)-Fluorobutenol 9a is a substrate for adenosine deaminase, whereas the E-isomer 8a is inert toward the enzyme. By contrast, analogue 8a inhibited the replication and cytopathic effect of HIV-1 in ATH8 cells with an IC50 of approximately 100 microM, but the Z-isomer 9a was inactive. This effect was accompanied by 36% cytotoxicity at 100 microM. Compounds 11 and 8d inhibited the growth of murine leukemia L1210 culture with IC50 = 89 and 60 microM, respectively.