Dimethylformamide → 2-Butoxy-8-methoxy-9-(tetrahydrofuran-3-ylmethyl)-9H-purin-6-amine

A stirring mixture of N2-butyl-8-methoxy-9H-purine-2,6-diamine trifluoroacetic acid salt (3.25 gm) and potassium carbonate (3.83 gm) in dry N,N-dimethylformamide (30 ml) was heated with stirring at 60° C. for 1 h. Tetrahydro-3-furanylmethyl methanesulfonate (2 gm, Isomer 1) was added and the stirring mixture heated at 90° C. for 3 h. The solvent was evaporated, water was added and the mixture extracted three times with ethyl acetate. The combined extracts were washed with water then brine, dried by passing through a hydrophobic frit and stripped to give an orange solid. This was purified by C18 reverse phase chromatography using water (0.1% formic acid)-acetonitrile (0.05% formic acid) as eluent (20-60%) and the appropriate fractions combined and evaporated to give the title compound as a light orange solid, yield 1.56 gm.