An ice-bath cooled solution of 6-bromo-1,2-benzisoxazol-3 (2H)-one (Intermediate 24) (0.05 g) and dry pyridine (0.05 ml) in dry dichloromethane (4 ml) was stirred under nitrogen and treated with triflic anhydride (60 μL). The solution was stirred at room temp. for 4 h, diluted with cyclohexane then applied to a Varian Bond-Elut SPE cartridge (silica, 1 g) and eluted with dichloromethane to give a yellow oil. The oil was dissolved in acetonitrile (2 ml) treated with 1,1-dimethylethyl 1-piperazinecarboxylate (0.04 g) and diisopropylethylamine (0.05 ml) then stirred at 70° under nitrogen for 20 h. The cooled reaction mixture was purified on a Varian Bond-Elut SPE cartridge (silica, 5 g) using dichloromethane:methanol to give the title compound as a white solid (0.016 g).
