Potassium Phosphate, Tribasic → 6-(4-Hydroxy-2-methylphenyl)benzo[d]isothiazole-3-carboxylic acid

Participants

Reaction Steps

To a degassed solution of 6-Bromo-benzo[d]isothiazole-3-carboxylic acid (0.42 g, 1.54 mmol), 3-Methyl-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl-phenol (0.54, 2.31 mmol), 2-Dicyclohexylphosphino-2′,6′-dimethoxy-1,1′-biphenyl (0.064 g, 0.154 mmol), and potassium phosphate (0.71 g, 3.1 mmol) in dioxane (8 mL) and water (4 mL) is added Pd(OAc)2 (6.5 mg, 0.03 mmol). The reaction is degassed again and heated to 80 degrees for 18 h. The reaction is cooled to room temperature and concentrated. The residue is diluted with EtOAc and 1N HCl. The layers are separated and concentrated. The crude material is diluted with 20 mL of MeOH and 2 mL H2SO4 and heated to reflux for 2 h. The reaction mixture is concentrated onto silica and purified by flash chromatography (20-50% EtOAc in Hexanes) to yield the title compound (0.12 g, 26%). ES/MS m/e 300.0 (M+1).

Provenance & Evidence