2-Chlorophenylboronic acid, pinacol ester

95-51-2

73183-34-3

870195-94-1

1. o-Chloroaniline (10 mmol) was dissolved in a mixture of 5 mL of distilled water and 3-4 mL of 50% tetrafluoroboric acid. 2. After cooling the reaction mixture to 0°C in an ice bath, sodium nitrite solution (0.69 g dissolved in 2 mL of distilled water) was added slowly and dropwise over 5 min. 3. The resulting mixture was stirred for 1 h. The precipitate was collected by filtration and redissolved in a minimal amount of acetone. 4. add diethyl ether to the solution until the disodium tetrafluoroborate precipitate precipitates, filter the precipitate, wash several times with diethyl ether and dry under vacuum. 5. Heterodinium salt (1.5 mmol), bis(pinacolato)diborane (1 mmol), and triphenylphosphine (2.0 equiv.) are weighed in a 25 mL Schlenk round bottom flask under nitrogen protection. 6. 3 mL of acetonitrile was added via syringe and the resulting solution was stirred at room temperature. 7. The reaction progress was monitored by GC-MS. 8. Upon completion of the reaction, the solution was filtered through a short silica gel column and the column was washed with ethyl acetate. 9. The filtrate was concentrated under pressure to obtain the crude product, which was subsequently purified by fast column chromatography on silica gel to obtain the final product 2-(2-chlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane.