Hydrochloric Acid → [2,6-dimethyl-4-(tetrahydro-2H-thiopyran-4-yloxy)phenyl]boronic acid

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Reaction Steps

To a solution of 4-(4-bromo-3,5-dimethylphenoxy)tetrahydro-2H-thiopyran (3.01 g, 10.0 mmol) in tetrahydrofuran (50 mL) was added dropwise a hexane solution (1.6 M, 6.57 mL, 10.5 mmol) of n-butyllithium at −78° C. The reaction mixture was stirred at the same temperature for 1.5 hr, and triisopropyl borate (6.92 mL, 30.0 mmol) was added. After warming to room temperature, the mixture was stirred overnight. The reaction mixture was ice-cooled, 2 M hydrochloric acid (50 mL) was added, and the mixture was stirred for 2.5 hr. The mixture was separated into the aqueous layer and the organic layer. The organic layer was washed with saturated brine and saturated aqueous sodium hydrogencarbonate while adjusting to neutral, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was washed with cold hexane to give the title compound (1.89 g, yield 71%) as colorless crystals.

Provenance & Evidence