To [1,6-diethyl-4-(tetrahydro-2H-pyran-4-ylamino)-1H-pyrazolo[3,4-b]pyridin-5-yl]methanol (24.9 g, 82 mmol) was added thionyl chloride (90 mL, 1.23 mmol) and the mixture was heated to 80° C. under an atmosphere of nitrogen. After 2 h the mixture was cooled, evaporated and the residue azeotroped with toluene. The residue was then dissolved in a solution of sodium azide (7.98 g, 123 mmol) in DMSO (120 mL). The mixture was stirred for 16 h. The above procedure was repeated on the same scale and the 2 reactions combined for work-up. The combined DMSO mixture was partitioned between ethyl acetate and aqueous sodium bicarbonate. The aqueous phase was extracted thoroughly with ethyl acetate and the combined organics were washed with water, then brine, dried and evaporated to afford 58.9 g of a brown solid. The product was purified by flash chomatography on 1.5 kg of silica using a step gradient from 3:1 to 2:1 cyclohexane/ethyl acetate to afford 39.94 g of the title compound. LC-MS m/z 330 (M+H)+, 2.21 min (ret time).
