Triethyl borate → 3-Methoxy-5,6,7,8-tetrahydronaphthalen-2-ylboronic acid

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Reaction Conditions

Reaction Steps

A 10 mL round bottom flask was charged with 3-bromo-5,6,7,8-tetrahydronaphthalen-2-yl methyl ether (560 mg, 2.32 mmol) and dried under high vacuum for 18 hours. The aryl bromide was diluted with THF (3.5 mL) and cooled to −78° C. with a dry ice/acetone bath. After 20 minutes, n-butyl lithium (2.5 M in hexane, 1.02 mL, 2.55 mmol) was added semi-drop wise. The reaction was kept at −78° C. for another hour before triethylborate (0.435 mL, 2.55 mmol) was added semi-drop wise and stirred at −78° C. for two hours. The reaction was quenched at −78° C. with 3M aq. HCl and allowed to warm to room temperature. The resulting biphasic mixture was partitioned between H2O and ethyl acetate (2×). The organics were combined and dried over Na2SO4, filtered and concentrated to give 510 mg (theoretical 478 mg) of 3-methoxy-5,6,7,8-tetrahydronaphthalen-2-ylboronic acid as an ivory solid. 1H NMR shows contamination with ˜11% of the des-bromo by product. 1H NMR (400 MHz, CDCl3) δ 7.51 (s, 1 H), 6.61 (s, 1 H), 5.73 (s, 2 H), 3.87 (s, 3 H), 2.78 (m, 2 H), 2.71 (m, 2 H), 1.79 (m, 4 H).

Provenance & Evidence