Hydrochloric Acid → (4-Isobutylphenyl)boronic acid

To a suspension of 0.68 g (28.15 mmol) of magnesium turnings in 50 mL of tetrahydrofuran under argon, a crystal of iodine was added and a solution of 4-bromo-isobutylbenzene (6.0 g, 28.15 mmol) in 25 mL of tetrahydrofuran was added at such a rate that a gentle reflux was maintained. The mixture was refluxed for an additional 1 hour, cooled to room temperature and added in portions over 15 min to a solution of trimethylborate (2.93 g, 28.15 mmol) in 50 mL of ether at -78° C. under argon. After 30 min at -78° C., the solution was warmed to room temperature, stirred for 90 minutes and 10% aqueous hydrochloric acid (100 mL) was added. After 10 minutes, the solution was extracted with ether (3×100 mL) and the combined ether extracts were extracted with 1M sodium hydroxide (3×100 mL). The aqueous extracts were acidified with dilute hydrochloric acid to pH 2 and extracted with ether (3×100 mL). The combined ether extracts were washed once with water (100 mL), dried and evaporated to afford 3.5 g of a white solid. Crystallization from ether/hexanes provided 2.3 g (46%) of compound A as a white solid in two crops, m.p. 134°-135° C.

1. temperaturea gentle reflux
2. temperaturewas maintained
3. temperatureThe mixture was refluxed for an additional 1 hour
4. temperaturethe solution was warmed to room temperature
5. waitAfter 10 minutes
6. extractionthe solution was extracted with ether (3×100 mL)
7. extractionthe combined ether extracts were extracted with 1M sodium hydroxide (3×100 mL)
8. extractionextracted with ether (3×100 mL)
9. washThe combined ether extracts were washed once with water (100 mL)
10. customdried
11. customevaporated

ORD record

ord-8c273848f05d484cb88e94b9e7ae1b87

Source dataset

uspto-grants-1996_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05514696