To a solution of N2-butyl-8-(methoxy)-9-[3-(tetrahydro-2H-pyran-3-yl)propyl]-9H-purine-2,6-diamine (198 mg) in dry methanol (20.8 ml) was added 4.0M hydrochloric acid in 1,4-dioxane (3.6 ml) in one go. The reaction was left to stir at room temperature for 4 hours. The reaction was neutralised by the addition of 2.0M sodium hydroxide solution and concentrated in vacuo. to give an off-white solid. To this solid was added water, triturated, and the solid filtered under vacuum until dry. This afforded the title compound as an off-white solid (151 mg).
