Triisopropyl borate → (4-Cyano-3-methylphenyl)boronic acid

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Reaction Steps

10.21 ml of n-butyllithium solution (1.6M in hexane) are added dropwise to a solution of 3.00 g of 4-bromo-2-methylbenzonitrile in 50 ml of dry tetrahydrofuran at −78° C. after stirring at this temperature for 30 minutes, 4.22 ml of triisopropyl borate are added, and then the mixture is stirred at −78° C. for a further 45 minutes. 30 ml of 1N are added to the reaction mixture. The phases are separated and the aqueeous phase is extracted three more times with 100 ml of diethyl ether/tetrahydrofuran (1,1) each time. The combined organic phases are dried with sodium sulphate, filtered and concentrated to 4 ml in vacuo. The remaining oil is mixed with 100 ml of pentane, and the precipitate which has separated out is filtered off with suction and washed twice with penteane. Drying under high vacuum results in 1.82 g of the title compound as a white solid. Rt. 2.93.

Provenance & Evidence