Triisopropyl borate → {3-[Bis(4-methoxybenzyl)amino]-4-chlorophenyl}boronic acid

Participants

Reaction Conditions

Reaction Steps

Under argon and at −78° C., 6.1 ml (15.25 mmol) of a 2.5 M solution of n-butyllithium in hexane were slowly added dropwise to a solution of 5.2 g (11.64 mmol) of 5-bromo-2-chloro-N,N-bis(4-methoxybenzyl)aniline in 100 ml of THF/diethyl ether (1:1). The reaction solution was stirred at −78° C. for 60 min, and 4.3 ml (18.62 mmol) of triisopropyl borate were then added slowly. The reaction solution was then stirred at −78° C. for another 15 min, then slowly warmed to room temperature and stirred at this temperature for another 3 h. 150 ml of ice-water were then metered in. The organic phase was separated off, and the aqueous phase was then extracted three more times with ethyl acetate. The combined organic phases were dried over sodium sulphate. After filtration, the solvent was removed under reduced pressure. The crude product was purified chromatographically on silica gel (mobile phase: initially cyclohexane/ethyl acetate 10:1→9:1→4:1, then dichloromethane/methanol 95:5). This gave 2.54 g (6.17 mmol, 53% of theory) of the title compound.

Provenance & Evidence