To a solution of 2-(butyloxy)-8-(methyloxy)-9H-purin-6-amine trifluoroacetate salt (3 g, 8.54 mmol) in DMF (30 ml) was added potassium carbonate (2.95 g, 21.35 mmol) and the mixture stirred at 60° C. for 1 hour under an atmosphere of nitrogen. The mixture was then cooled to room temperature and 1-bromo-6-chlorohexane (1.27 ml, 8.54 mmol) was added and the reaction heated to 50° C. and stirred overnight under an atmosphere of nitrogen. The reaction mixture was diluted with water (ca. 50 ml) and extracted with ethyl acetate (2×70 ml). The combined organic extracts were dried (MgSO4), filtered and the filtrate concentrated to give an orange oil (ca. 3.5 g). This material was dissolved in dichloromethane and purified on a Flashmaster II (70 g aminopropyl cartridge) using a 0-100% ethyl acetate in cyclohexane gradient over 60 mins. The appropriate fractions were combined and evaporated in vacuo to give the title compound as a yellow oil which solidified to a pale yellow solid (1.2 g).
