Triethyl borate → (6-Ethylpyridin-3-yl)boronic acid

Temperature

-78 °C

Into a 500-mL 3-necked round-bottom flask (1 atm) purged and maintained with an inert atmosphere of nitrogen, was placed 5-bromo-2-ethylpyridine (3 g, 16.12 mmol, 1.00 equiv) and tetrahydrofuran (200 mL). To the resulting mixture was then added n-BuLi (8.4 mL, 2.5 M) dropwise with stirring at −78° C. The resulting solution was stirred for 30 min at −78° C. in an ethanol/N2 bath. To the resulting mixture was then added triethyl borate (4.7 g, 32.19 mmol, 2.00 equiv) dropwise with stirring at −78° C. The resulting solution was allowed to react, with stirring, overnight at room temperature. The reaction was then quenched by the addition of methanol (20 mL) and water (0.5 mL). The resulting mixture was then concentrated under vacuum. The resulting solution was diluted with methanol (10 mL). The resulting residue (10 mL) was purified by Flash-Prep-HPLC (reversed column) with the following conditions (IntelFlash-1): Column, C18 silica gel; mobile phase, A:water with trifluoroacetic acid (0.05%); B: MeCN=1/100 increasing to A:water with trifluoroacetic acid (0.05%); B: MeCN=20/100 within 25 min; Detector, UV 254 nm to yield of (6-ethylpyridin-3-yl)boronic acid as a white solid.

1. customInto a 500-mL 3-necked round-bottom flask (1 atm) purged
2. temperaturemaintained with an inert atmosphere of nitrogen
3. customto react
4. stirringwith stirring, overnight at room temperature
5. customThe reaction was then quenched by the addition of methanol (20 mL) and water (0.5 mL)
6. concentrationThe resulting mixture was then concentrated under vacuum
7. additionThe resulting solution was diluted with methanol (10 mL)
8. customThe resulting residue (10 mL) was purified by Flash-Prep-HPLC (reversed column) with the following conditions (IntelFlash-1)
9. waitB: MeCN=20/100 within 25 min

ORD record

ord-a3bfc359e6774747908a5c2ee8d35cac

Source dataset

uspto-grants-2014_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08912227B1