Trimethyl borate → 1-Methyl-3-(trifluoroMethyl)pyrazole-5-boronic acid

Temperatur

-78 °C

To a stirred solution of 1-methyl-3-(trifluoromethyl)-1H-pyrazole (1.89 g, 12.6 mmol) in anhydrous tetrahydrofuran (20 mL) under nitrogen cooled to −78° C. was added n-butyllithium (8.3 mL, 1.6 M solution in hexanes, 13.2 mmol) slowly over 5 minutes. The resulting yellow solution was stirred at −78° C. for 1 hour and trimethyl borate (1.56 mL, 13.9 mmol) was then added slowly. The reaction flask was covered in foil and allowed to warm to room temperature for 16 hours. The white solution was quenched with aqueous 1 M hydrogen chloride solution (10 mL) and stirred at room temperature for 1.5 hours. The mixture was extracted with ethyl acetate (2×30 mL), dried with anhydrous magnesium sulphate and evaporated in vacuo to give an off-white foam (2.11 g). The foam was triturated with dichloromethane, filtered and dried in vacuo to afford the title compound as a white solid (1.57 g, 64%).

1. temperatureto warm to room temperature for 16 hours
2. customThe white solution was quenched with aqueous 1 M hydrogen chloride solution (10 mL)
3. stirringstirred at room temperature for 1.5 hours
4. extractionThe mixture was extracted with ethyl acetate (2×30 mL)
5. dry with materialdried with anhydrous magnesium sulphate
6. customevaporated in vacuo

ORD-Eintrag

ord-90f082b8dd944f97a80ceccf80c09ca3

Quelldatensatz

uspto-grants-2015_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US09096500B2