Pinacol → 5-Pentylthiophene-2-boronic acid pinacol ester

Participants

Reaction Conditions

Reaction Steps

To a cooled (−78° C.) mixture of 2-n-pentylthiophene (5.0 g, 32.1 mmol) and pinacol (11.5 g, 97.23 mmol) in anhydrous THF (60 mL) was added dropwise to a solution of n-BuLi (22.3 mL, 35.6 mmol) in hexane. The mixture was stirred at −78° C. for 10 minute. The reaction mixture was then brought to 0° C. and stirred for 1 h before cooling to −78° C. before the addition of triisopropyl borate (7.3 g, 38.9 mmol) in THF (24 mL) using a dropping funnel. The mixture was slowly brought to room temperature while stirring overnight. The crude product was purified by flash chromatography (silica gel. eluent: hexane/EA) 10:1) to afford a reddish brown liquid 7.35 g (81.0%).

Provenance & Evidence