Triisopropyl borate → (5-Methyl-1-benzofuran-2-yl)boronic acid

Temperature

-10 °C

n-Butyl lithium (35.16 ml) was added dropwise to a stirred solution of THEDA (9.58 ml) and 5-methylbenzofuran (8.22 g) in ether (250 ml) maintaining the temperature below -60° C. throughout. The solution was warmed to about -10° C. over 45 minutes and stirred at this temperature for 30 minutes. A precipitate formed on warning. The suspension was cooled and triisopropylborate (43 ml) was added, maintaining the temperature below -60° C. The solution was warmed gradually to room temperature before quenching with 2N HCl (70 ml). The mixture was extracted with ether (3×50 ml) and the combined organic extracts washed with 2N HCl (4×30 ml), water (2×30 ml) and dried before evaporation to give the title compound as an orange solid (12.75 g).

1. temperaturemaintaining the temperature below -60° C. throughout
2. customA precipitate formed on warning
3. temperatureThe suspension was cooled
4. temperaturemaintaining the temperature below -60° C
5. temperatureThe solution was warmed gradually to room temperature
6. custombefore quenching with 2N HCl (70 ml)
7. extractionThe mixture was extracted with ether (3×50 ml)
8. washthe combined organic extracts washed with 2N HCl (4×30 ml), water (2×30 ml)
9. customdried before evaporation

ORD record

ord-b26d0fcca28a42ee84273a20909565ea

Source dataset

uspto-grants-1994_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05310927