To a solution of 2-(butyloxy)-8-(methyloxy)-9H-purin-6-amine. trifluoroacetate salt (2.56 g, 7.29 mmol) in DMF (60 ml) was added potassium carbonate (4.03 g, 29.1 mmol) and the mixture was left to stir at 60° C. for one hour under an atmosphere of nitrogen. Reaction was then cooled to room temperature and to this was added phenylmethyl 3-(bromomethyl)-1-piperidinecarboxylate (2.275 g, 7.29 mmol). The reaction was bought back up to 50° C. and left to stir overnight. The reaction mixture was diluted with water (˜40 ml) and partitioned with a solvent mix of 1:1 ethyl acetate:DCM (40 ml). The organic layer was separated using hydrophobic frit and was concentrated in vacuo to give pale yellow thick oil. The crude material was dissolved in 1:1 DMSO:MeOH (5 ml) and half of this solution was initially purified on reverse-phase chromatography using a high pH system on a 330 g C18 silica column. The gradient used was the following:
