Pyrrolopyrimidine nucleosides. Part X. Synthesis of certain 4,5-disubstituted 7-(β-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidines related to toyocamycin and sangivamycin

Abstract

The reactivity of the cyano-group of 4-chloro-7-(β-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile (5) towards various nucleophiles has been studied. Although both exocyclic groups (Cl and CN) reacted with various nucleophiles, the initial reaction was always a nucleophilic displacement of the 4-chloro-group, and the cyano-group reacted only after this had occurred. Additional studies on the reactivity of the 5-cyano-group towards various nucleophiles (MeNH₂, NH₂OH, HS^–, MeS^–), were conducted with groups other than Cl at C-4.

The synthesis of 7-(β-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile (10) is also reported. Studies comparing the susceptibility towards nucleophilic attack of the 5-cyano-group of (10) with that of the 5-cyano-group of toyocamycin and deaminotoyocamycin (1a) indicate that under both basic and acidic conditions the cyano-function of (10) is the more reactive.