The Importance of the 4′-Hydroxyl Hydrogen for the Anti-trypanosomal and Antiviral Properties of (+)-5′-Noraristeromycin and Two 7-Deaza Analogues Original Research Article

(+)-5′-Noraristeromycin (1) has shown significant antiviral activity while its 7-deaza analogue 2 is an anti-trypanosomal candidate. To determine the relevance of the 4′-hydroxyl hydrogen in these activities, a derivative of 1 (that is, 3) where the C-4′ hydroxyl hydrogen has been replaced by a methyl group has been prepared beginning with palladium (0) mediated coupling of the sodium salt of N6-benzoyladenine (9) and (1S,4R)-4-methoxy-2-cyclopenten-1-yl acetate (5). The synthesis of compound 5 is described from (1S,4R)-1-[(tert-butyldimethylsilyl)oxy]-4-hydroxycyclopent-2-ene (6) in three steps. Analogous preparations of the 7-deaza and 8-aza-7-deaza derivatives of 3 related to 2 (that is, 4 and 12) are also reported. The new derivatives (3, 4, and 12) failed to show improved antiviral activity. Compound 12 was the only derivative with some anti-trypanosomal activity, giving 40% inhibition of growth at 100 μM against bloodstream forms of a Typanosoma brucei brucei isolate in a standard in vitro screen. This study indicated that the C-4′-hydroxyl hydrogen plays a role in the medicinal properties of 1 and 2.