Synthesis of 6-C-Substituted 9-Tetrahydrofuranylpurine Derivatives

6-Dicyanomethylene-9-tetrahydrofuranylpurine (4), which was obtained by the reaction of 9H-1, 6-dihydropurine-Δ6, α-propanedinitrile (3) with 2, 3-dihydrofuran, has been catalytically hydrogenated to the α-(aminomethylene)-9-(tetrahydrofuran-2-yl)-9H-purine-6-acetonitrile (5) in good yield using N, N-dimethylformamide-benzene as a solvent over Pd-C under medium pressure. Substitution of 5 with amines gave the corresponding alkylaminomethylene purines (6 and 7). Reaction of 5 with hydrazine gave the pyrazole derivative (8).