Tetrahydrofuran → 2-Chloropyridine-5-boronic acid

Participants

Reaction Conditions

Reaction Steps

In a flask replaced by nitrogen, tetrahydrofuran solution (80 g) containing 5-bromo-2-chloropyridine (9.6 g, 50.0 mmol) was charged, and cooled at −78° C., and then n-hexane solution of n-butyllthium (15% by weight, 24.6 g, 57.5 mmol) was added dropwise at −78° C. Next, at −78° C., trimethoxyborane (5.7 g, 55.0 mmol) was added dropwise. After 30 minutes from adding dropwise, cooling bath was removed off, and the reaction mixture was stirred at room temperature overnight. Then, 10% by weight of hydrochloric acid (50 g) was added under ice cooling condition, and the reaction mixture was stirred for 1.5 hours, and then neutralized by adding 40% by weight of sodium hydroxide aqueous solution (15 g). Ethyl acetate (50 g) was added to the reaction mixture, and the reaction mixture was stirred for 1.0 hour, and then left to stand to separate organic layer. Organic layer was dried with anhydrous magnesium sulfate, and then condensed under reduced pressure to obtain 6-chloro-3-pyridylboronic acid (6.9 g, 44.0 mmol).

Provenance & Evidence