1-Chloro-5-(5-{3-chloro-4-[(1-methylethyl)oxy]phenyl}-1,2,4-oxadiazol-3-yl)isoquinoline (D7; 200 mg, 0.5 mmol), di-isopropylethylamine (0.873 ml, 1.0 mmol) and 1,1-dimethylethyl β-alaninate (726 mg, 5 mmol; available e.g. from Novabiochem) were placed into a 20 ml microwave vial, and N-methyl-2-pyrrolidinone (NMP, 8 ml) was added. The mixture was heated under microwave irradiation at 180° C. for one hour, diluted with methanol and chromatographed over an SCX cation exchange column (Biotage), which was washed with methanol and dichloromethane and eluted with methanolic ammonia. Washings and eluate from the SCX column were re-combined and evaporated in vacuo until only NMP remained. Water (20 ml) was added to the reaction mixture and a solid precipitate formed. The precipitate was collected by filtration and azeotroped twice with toluene. The solid was dissolved in dichloromethane (5 ml) and chromatographed on a silica column, eluting with dichloromethane to yield the title compound (38 mg) as a pale yellow solid.
