In xylene (10 ml), 2-bromo-6-chlorobenzothiazole (760 mg, 3.06 mmol), methyl 4-amino-3-chlorophenylacetate (610 mg, 3.06 mmol), and pyridinium•p-toluenesulfonate (PPTS) (230 mg, 0.92 mmol) were heated under reflux for 1 hour. After cooling, the reaction mixture was distilled under reduced pressure to remove the solvent. The residue was purified by chromatography on a silica gel column, whereby from n-hexane/ethyl acetate (6:1, v/v) eluate fractions, methyl (4-(6-chloro-2-benzothiazolyl)amino-3-chlorophenyl)acetate (271 mg, 24%) was obtained as a pale yellow solid.
