Practical and Divergent Synthesis of Carbocyclic Pyrazolo[3,4‐d]pyrimidine Nucleoside Analogues

A concise set of 4-substituted pyrazolo[3,4-d]pyrimidine carboriboside analogues was synthesized in a divergent fashion through a central intermediate. An oxaziridine reagent allowed to synthesize a crucial hydrazine glycon intermediate, which was transformed via a base build-up strategy to the desired intermediate using a commercially available pyrimidine building block. Reaction with a variety of nucleophiles allowed late-stage diversification. All analogues were evaluated for activity against a representative panel of Trypanosomatida. A methoxy-substituted analogue displayed single-digit micromolar activity against two subspecies of Trypanosoma brucei in cellular assays.