FC(F)(F)C(O)=O.[CH2:8]([NH:12][C:13]1[N:21]=[C:20]2[C:16]([N:17]=[C:18]([O:22][CH3:23])[NH:19]2)=[C:15]([NH2:24])[N:14]=1)[CH2:9][CH2:10][CH3:11].C(=O)([O-])[O-].[K+].[K+].CS(O[CH2:36][CH2:37][CH:38]1[CH2:43][CH2:42][CH2:41][CH2:40][O:39]1)(=O)=O>CN(C=O)C>[CH2:8]([NH:12][C:13]1[N:21]=[C:20]2[C:16]([N:17]=[C:18]([O:22][CH3:23])[N:19]2[CH2:36][CH2:37][CH:38]2[CH2:43][CH2:42][CH2:41][CH2:40][O:39]2)=[C:15]([NH2:24])[N:14]=1)[CH2:9][CH2:10][CH3:11]A mixture of N2-butyl-8-methoxy-9H-purine-2,6-diamine trifluoroacetic acid salt (200 mg) and potassium carbonate (236 mg) in dry DMF (2 mL) were heated at 60° C. with stirring for 1 h. 2-(Tetrahydro-2H-pyran-2-yl)ethyl methanesulfonate (142 mg) was added and the reaction was continued for 3 h at 60° C. The mixture was quenched with water and extracted with EtOAc (×3). The combined organics were washed with water and brine, dried using a hydrophobic frit and evaporated to give crude material (250 mg). The material was purified by C18 reverse phase chromatography using water (containing 0.1% formic acid)-acetonitrile (containing 0.05% formic acid) as eluent (20-60%) and the appropriate fractions combined and evaporated to remove acetonitrile. The remaining aqueous mixture was made basic with saturated sodium hydrogen carbonate, extracted three times with dichloromethane and the combined extracts dried by passing through a phase separation cartridge then evaporated to give 75 mg of material which was recrystallised from ether/light petrol yielding the title compound as a solid, 54 mg.
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