Hydrochloric Acid → 2-Formyl-3-thiopheneboronic acid

Participants

Reaction Steps

A 1.1 N solution of n-butyllithium in hexane (28 ml). was added dropwise (10 mins) to a solution of 2-(3-bromo-2-thienyl)-1,3-dioxalane (3) (6.6 g, 28.1 mmol) in anhydrous ether (30 ml) at −70° C. After stirring for 10 mins, butyl borate (9.1 ml, 33.7 mmol) in anhydrous ether (20 ml) was added in a single portion. The reaction mixture was stirred for 4 hrs at −70° C. and then left to return to room temperature. 1 N hydrochloric acid (20 ml) was added, and the mixture was left for 1 hr with stirring. The aqueous phase was extracted with ether and the combined ether phases were washed with a solution of sodium bicarbonate, dried (Na2SO4), and evaporated under reduced pressure to give the intermediate (4) (2.2 g, 14.1 mmol, 50% yield) as a brown solid.

Provenance & Evidence