To a solution of 2-(butyloxy)-8-(methyloxy)-9H-purin-6-amine trifluoroacetate salt (for example, as prepared for Intermediate 6) (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. The reaction mixture was then cooled to room temperature and to this was added phenylmethyl 3-(bromomethyl)-1-piperidinecarboxylate (commercially available, for example, from AniChem, or for a prep see International Patent Application Publication Number WO1999/45006) (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:
