A solution of 4-(4-(8-oxa-3-azabicyclo[3.2.1]octan-3-yl)-1-(1,3-dimethoxypropan-2-yl)-1H-pyrazolo[3,4-d]pyrimidin-6-yl)aniline (65 mg, 0.15 mmol) in dichloromethane (1.5 mL) was treated with triethylamine (0.2 mL), followed by a solution of triphosgene (23 mg, 0.08 mmol) in dichloromethane (1 mL). After the passage of 10 minutes, the appropriate nucleophile—in the case, ethylene glycol (84 μL, 1.5 mmol)—was added to the 3-(1-(1,3-dimethoxypropan-2-yl)-6-(4-isocyanatophenyl)-1H-pyrazolo[3,4-d]pyrimidin-4-yl)-8-oxa-3-azabicyclo[3.2.1]octane (“isocyanate”) mixture. After 3 hours, the reaction mixture was concentrated to dryness under reduced pressure. The residue was purified by reverse-phase high performance liquid chromatography using a Phenomenex Prodigy 21 mm×250 mm column, running a gradient elution of 5% acetonitrile/95% of 0.1% aqueous trifluoroacetic acid to 100% acetonitrile to provide 2-hydroxyethyl(4-{1-[2-methoxy-1-(methoxymethyl)ethyl]-4-(8-oxa-3-azabicyclo[3.2.1]oct-3-yl)-1H-pyrazolo[3,4-d]pyrimidin-6-yl}phenyl)carbamate (41 mg, 53%). MS (ES+): 513.2 (M+H)+
