Triisopropyl borate → 2-(5-borono-1H-indol-3-yl)acetic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of (5-bromo-1H-indol-3-yl)-acetic acid (1 g, 3.94 mmol) in THF (66 mL) at −78 ° C. is added tert-butyl lithium (1.7 M in pentane, 11.6 mL, 19.7 mmol) dropwise and stirred at −78° C. for 30 minutes. at −30° C. for 1 hour. Cooled down to −78° C. again and treated dropwise with triisopropyl borate (4.53 mL, 19.7 mmol). The reaction mixture is allowed to warm to room temperature during 1 hour quenched with 2 N hydrochloric acid. This mixture is extracted with ether. The extract is dried over sodium sulfate and concentrate to obtain an oil which is subjected to silica gel chromatography affording 3-carboxymethyl-1H-indol-5-yl boronic acid (185 mg, 20%) as a solid.

Provenance & Evidence