2-Methylthiophene → (5-Methylthiophen-2-yl)boronic acid

Temperature

0 °C

n-BuLi (2.38 M, 16 ml) was slowly added to a solution of 2-methyl thiophene (3.0 g, 31 mmol) in THF (20 ml) at −78° C. The solution was kept at −78° C. For 10 min. then warmed to 0° C. for an additional 0.5 hr. The solution was then transferred by steel canula under nitrogen into a vessel containing triisopropylborate (6.3 g, 33 mmol) in ether (15 ml) at −78° C. The resulting milky white solution was stirred at −78° C. for 20 min. then at room temperature for 2 hours. The reaction was quenched by the addition of 10% aqueous HCl (5.0 ml) and the solution was extracted into ether. The combined ether extracts were extracted with 10 M NaOH (2×30 ml), the aqueous extracts were acidified with dilute HCl to pH 2 and extracted into ether (3×25 ml). The combined ether extracts were washed once with water (10 ml), once with brine (10 ml) and dried and evaporated to give 3.91 g 2-methylthiophene-5-boronic acid as a light brown solid. This was used in the next step with no further purification.

1. customwas kept at −78° C
2. waitat room temperature for 2 hours
3. customThe reaction was quenched by the addition of 10% aqueous HCl (5.0 ml)
4. extractionthe solution was extracted into ether
5. extractionThe combined ether extracts were extracted with 10 M NaOH (2×30 ml)
6. extractionextracted into ether (3×25 ml)
7. washThe combined ether extracts were washed once with water (10 ml), once with brine (10 ml)
8. customdried
9. customevaporated

ORD record

ord-b82f839b25574a9684ba52a63c3827b1

Source dataset

uspto-grants-2003_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06613804B2