Hydrochloric Acid → (6-Methoxy-1-benzothiophen-2-yl)boronic acid

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Reaction Conditions

Reaction Steps

To a solution of 6-methoxybenzo[b]thiophene (18.13 g, 0.111 mol) in 150 mL of anhydrous tetrahydrofuran (THF) at -60° C. was added n-butyllithium (76.2 mL, 0.122 mol, 1.6 M solution in hexanes), dropwise via syringe. After stirring for 30 minutes, triisopropyl borate (28.2 mL, 0.122 mol) was introduced via syringe. The resulting mixture was allowed to gradually warm to 0° C. and then distributed between 1N hydrochloric acid and ethyl acetate (300 mL each). The layers were separated, and the organic layer was dried over sodium sulfate. Concentration in vacuo produced a white solid that was triturated from ethyl ether hexanes. Filtration provided 16.4 g (71%) of 6-methoxybenzo[b]thiophene-2-boronic acid as a white solid. mp 200° C. (dec). 1H NMR (DMSO-d6) d 7.83 (s, 1H), 7.78 (d, J=8.6 Hz, 1H), 7.51 (d, J=2.0 Hz, 1H), 6.97 (dd, J=8.6, 2.0 Hz, 1H), 3.82 (s, 3H). FD mass spec: 208.

Provenance & Evidence