Hydrochloric Acid → 4-(5,5-Dimethyl-1,3,2-dioxaborinan-2-yl)-2-methylbenzonitrile

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Reaction Conditions

Reaction Steps

A solution of 4-bromo-2-methylbenzonitrile (1.0 g) in tetrahydrofuran (16 mL) was cooled to an external temperature of −78° C. in a nitrogen atmosphere, and a solution of n-butyllithium in hexane (1.57 M, 3.5 mL) was added dropwise. After stirring at −78° C. for 40 minutes, triisopropyl borate (1.5 mL) was added dropwise and the mixture was stirred at room temperature for 1.5 hours. 1 M hydrochloric acid (10 mL) was added to the reaction solution, followed by extraction with diethyl ether. The organic layer was washed with water and brine, dried over sodium sulfate and filtered. The solvent was then evaporated under reduced pressure. The residue was dissolved in toluene (4 mL) and tetrahydrofuran (3 mL), and 2,2-dimethyl-1,3-propanediol (531 mg) and anhydrous magnesium sulfate (catalytic amount) were added, after which the mixture was stirred at room temperature for five minutes. The insoluble matter in the reaction solution was filtered off, and then the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=50:1→20:1) to give the title compound as a colorless solid (778 mg, 67%).

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