To a solution of 7-Bromo-3-(4-chloro-phenyl)-4-hydroxy-isothiazolo[5,4-c]pyridine-5-carboxylic acid ethyl ester (152.5 mg, 0.369 mmol) in THF (5.2 mL) were added Trimethylsilylacetylene (0.105 mL, 0.738 mmol), PdCl2(PPh3)2 (51.8 mg, 0.0738 mmol), CuI (28.1 mg, 0.147 mmol) and isopropylamine (0.32 mL, 2.28 mmol). The reaction mixture was refluxed for 16 h. After cooling to rt, the mixture was diluted with EtOAc (20 mL), and filtered. The filtrate was concentrated in vacuo and purified by flash chromatography on silica gel. Elution with 0-20% EtOAc/CH2Cl2, gave the desired product (60 mg) as white solid: MS (m/z) 431.1 (M+1).
