Hydrochloric Acid → 2-(2,3-Difluoro-4-trimethylsilylphenyl)-5,5-dimethyl-1,3,2-dioxaborinane

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Reaction Steps

625 ml (1 mol) of 1.6 M BuLi are added dropwise at −78° C. to a solution of 169 g (910 mmol) of 1,2-difluoro-3-trimethylsilylbenzene (5) in 1.4 l of dry tetrahydrofuran. After 15 minutes, 276 ml (1.2 mol) of triisopropyl borate are added dropwise. The mixture is allowed to warm to room temperature overnight 200 ml of water, 200 ml of methyl tert-butyl ether and 100 ml of conc. HCl are subsequently added. The organic phase is washed with water (2×100 ml) and sat. NaCl (1×100 ml) and dried using magnesium sulfate, and the solvent is removed under reduced pressure. The oily residue is dissolved in 270 ml of THF, and 94 g (910 mmol) of neopentyl glycol and 455 g of magnesium sulfate are added. After the mixture has been stirred for 1 hour, the solvent is removed under reduced pressure, and petroleum ether (273 ml) is added to the oily residue. Precipitated neopentyl glycol is removed by filtration. 251 g (87%) of 6 crystallise from the filtrate at −25° C.

Provenance & Evidence