To a mixture of 3-methyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine (1.10 g, 7.37 mmol), cesium carbonate (3.2 g, 10 mmol) and potassium iodide (111 mg, 0.670 mmol) in DMF (20 mL) was added tert-butyl 3-[3-chloro-5-(1-chloroethyl)-6-ethoxy-2-fluorophenyl]azetidine-1-carboxylate (2.63 g, 6.70 mmol) and the mixture was stirred at 90° C. for 3 h. The solvent was removed in vacuo. The residue was diluted with ethyl acetate and water. Aqueous layer was extracted with ethyl acetate twice. The combined organic layers were washed with water, brine, dried over Na2SO4, filtered and concentrated. The residue was purified on silica gel column (eluting with 100% ethyl acetate) to give the desired product as a foam (2.15 g, 63%). LCMS calculated for C24H31ClFN6O3 (M+H)+: m/z=505.2; Found: 505.2.
