A mixture of 3-hydroxy-2-methylpyridine (Aldrich Chemical Company, Inc., Milwaukee, Wis., USA; 1.25 mg, 0.011 mmol), 4-chloro-1-[1-(3-isopropyl-[1,2,4]oxadiazol-5-yl)-piperidin-4-yl]-1H-pyrazolo[3,4-d]pyrimidine (Intermediate 22; 4 mg, 0.012 mmol) and potassium carbonate (3 mg, 0.022 mmol) in DMF (0.5 mL) was heated in a microwave at 160° C. for 10 min, but TLC showed no reaction. Potassium carbonate (3 mg, 0.022 mmol) and DMF (0.1 mL) were added and the reaction mixture was heated in a microwave at 180° C. for 15 min. The solvent was evaporated and water was added. The mixture was extracted with ethyl acetate and the extracts were dried, held under high vacuum, and purified by HPLC to give 1-[1-(3-Isopropyl-[1,2,4]oxadiazol-5-yl)-piperidin-4-yl]-4-(2-methyl-pyridin-3-yloxy)-1H-pyrazolo[3,4-d]pyrimidine (1.8 mg, 39%).
