SiliaBond Carbonate (Silicycle, Quebec City, Canada; 0.69 mmol/g loading; 395 mg, 0.27 mmol) was added to a mixture of [1-(3-isopropyl-[1,2,4]oxadiazol-5-yl)-piperidin-4-yl]-hydrazine trifluoroacetic acid salt (from Step 4; 185 mg, 0.55 mmol) and 4,6-dichloro-pyrimidine-5-carbaldehyde (Intermediate 16; 81 mg, 0.45 mmol) in anhydrous acetonitrile (3 mL). The reaction mixture was heated in a Biotage Optimizer microwave at 140° C. for 5 min. The resin was filtered off and washed with acetonitrile. The solvent was evaporated and the residue was purified on a silica column (ISCO 12 g) eluting with 0-3% methanol/dichloromethane to give 4-chloro-1-[1-(3-isopropyl-[1,2,4]oxadiazol-5-yl)-piperidin-4-yl]-1H-pyrazolo[3,4-d]pyrimidine (31 mg, 20%). Mass spectrum (ES) MH+=348.
