Trimethyl borate → (6-Methoxypyridin-3-yl)boronic acid

Temperature

-75.0999984741211 °C

5-Bromo-2-methoxypyridine (152 g) was dissolved in tetrahydrofuran anhydride (1520 mL) under stirring in nitrogen atmosphere, followed by cooling to −75.1° C. as bulk temperature. Under cooling and stirring, 380 mL of a 2.46 mol/L butyl lithium solution was added dropwise thereinto, followed by the dropwise addition of 192 mL of trimethoxyborane. The cooling bath was removed 30 minutes after completion of the dropwise addition, and the mixture was stirred at room temperature overnight. On the next day, 1.5 L of a 2 mol/L aqueous solution of hydrochloric acid was added thereto, followed by stirring for 1.5 hours. Then, it was neutralized with 460 mL of a 5 mol/L aqueous solution of sodium hydroxide. It was then extracted with 1 L of ethyl acetate, and the resulting aqueous layer was extracted again with 1 L of ethyl acetate. The combined organic layer was washed twice with 1 L of 10% saline water, dried over anhydrous magnesium sulfate, and then evaporated, to give 105 g (88%) of the title compound as a slightly yellowish white solid.

1. temperatureUnder cooling
2. stirringstirring
3. customThe cooling bath was removed 30 minutes
4. additionafter completion of the dropwise addition
5. stirringthe mixture was stirred at room temperature overnight
6. additionOn the next day, 1.5 L of a 2 mol/L aqueous solution of hydrochloric acid was added
7. stirringby stirring for 1.5 hours
8. extractionIt was then extracted with 1 L of ethyl acetate
9. extractionthe resulting aqueous layer was extracted again with 1 L of ethyl acetate
10. washThe combined organic layer was washed twice with 1 L of 10% saline water
11. dry with materialdried over anhydrous magnesium sulfate
12. customevaporated

ORD record

ord-b8322f272c604ceeb5a72a69aebb39e0

Source dataset

uspto-grants-2011_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07939549B2