A mixture of 2-chloro-5-fluoro-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyrimidin-4-amine hydrochloride (246 mg, 0.760 mmol, 1 equiv), 3-cyclopropyl-4-fluoro-5-(1H-tetrazol-1-yl)benzenamine (200 mg, 0.912 mmol, 1.2 equiv), and PTSA monohydrate (116 mg, 0.608 mmol, 0.8 equiv) in IPA (8 mL) were heated to 70° C. for 3 days. LCMS indicated 2-4% of the cleaved tetrazole product. After cooling to ambient temperature, the crude mixture was quenched with 2M NH3/MeOH followed by concentrating to dryness and repeating twice. The crude product was purified by flash chromatography and eluted with DCM:2M NH3/MeOH=100:0 to 96:4 using 1% 2M NH3/MeOH increments to provide the desired product which was recrystallized with IPA/hexane to give desired compound (154 mg, 43%) as a solid.
