A solution of N′-[4-(3-isopropyl-[1,2,4]oxadiazol-5-yl)-cis-cyclohexyl]-hydrazinecarboxylic acid tert-butyl ester (Intermediate 13; 309 mg, 2.03 mmol) in tetrahydrofuran (3 mL) was added to a cooled (0° C.) solution of 4,6-dichloro-pyrimidine-5-carbaldehyde (Intermediate 16; 169 mg, 0.95 mmol) and diisopropylethylamine (337 μL, 1.9 mmol) in tetrahydrofuran (2 mL), and the mixture was stirred at 0° C. for 30 min and then at room temperature for 5 h. The mixture was filtered, and the filtrate was washed with brine. The aqueous layer was extracted with methyl tert-butyl ether and the organic extracts were combined, washed with brine, dried (sodium sulfate), filtered, evaporated, and held under high vacuum. Toluene (10 mL) was added and the mixture was held at 110° C. overnight. The solvent was evaporated and the residue was purified on a Supelco 23 g column, eluting with 0-3% methanol/dichloromethane to give 4-chloro-1-[4-(3-isopropyl-[1,2,4]oxadiazol-5-yl)-cis-cyclohexyl]-1H-pyrazolo[3,4-d]pyrimidine (211 mg, 64%).
