Pyridinium chloride → 7-Methylbenzo[d]isothiazol-4-ol

Participants

Reaction Steps

A solution of 7-bromo-4-methoxy-benzo[d]isothiazole (460 mg, 1.88 mmol), K2CO3 (780 mg, 5.64 mmol), and Pd(PPh3)4 (217 mg, 0.188 mmol) in 1,4-dioxane (5 mL) was added trimethylboroxine (290 μL, 2.07 mmol) and the solution was heated to 110° C. for 18 h. The reaction was cooled to rt and diluted with water and dichloromethane. The organic phase was separated and the aqueous phase was extracted with 2×30 mL dichloromethane. The combined organic phases were dried (MgSO4) and concentrated in vacuo. The residue was purified by flash chromatography eluting silica gel with EtOAc:hexane [0:100 to 1:10] to yield 4-methoxy-7-methyl-benzo[d]isothiazole (88 mg, 26%). A method similar to that described for the preparation of benzo[d]isothiazol-4-ol (above) using 4-methoxy-7-methyl-benzo[d]isothiazole (88 mg, 0.491 mmol) and pyridine hydrochloride (567 mg, 5 mol) gave the title compound (30 mg, 37%): δH (300 MHz, CDCl3): 8.99 (1H, s), 7.15 (1H, d, J=7.5 Hz), 6.70 (1H, d, J=7.5 Hz), 2.45 (3H, s).

Provenance & Evidence