Trimethyl borate → [2-Borono-4-(trifluoromethyl)phenoxy]-acetic acid

Temperature

-40 °C

A solution of sec-butyllithium (66 ml, 1.4M in cyclohexane) was added dropwise over 10 min to a stirred solution of the product from step (iii) (9.44 g) in THF (100 ml) at −78° C. After 3 h the mixture was warmed to −40° C. for 5 min, then cooled to −78° C. Trimethylborate (14.1 ml) was added, then after 10 min the reaction quenched with 2M hydrochloric acid. The mixture was warmed to RT and the organic phase separated. The aqueous layer was extracted with ethylacetate, the organics combined and evaporated under reduced pressure. The residue was dissolved in methanol (500 ml) then bondelut-NH2 resin(180 g) added and the mixture swirled for 0.5 h then filtered. The resin was washed with 10% acetic acid/methanol, the washings then evaporated under reduced pressure and dried under high vacuum. The residue was dissolved in methanol (50 ml), tetrahydrofuran (50 ml) and saturated aqueous sodium hydroxide solution (2 ml), left for 30 min then 2M hydrochloric acid (50 ml) added and the organics evaporated under reduced pressure. The residual aqueous layer was extracted with ethylacetate, the organics separated, dried and evaporated under reduced pressure, yield 5.05 g.

1. temperaturecooled to −78° C
2. customafter 10 min the reaction quenched with 2M hydrochloric acid
3. temperatureThe mixture was warmed to RT
4. customthe organic phase separated
5. extractionThe aqueous layer was extracted with ethylacetate
6. customevaporated under reduced pressure
7. dissolutionThe residue was dissolved in methanol (500 ml)
8. additionbondelut-NH2 resin(180 g) added
9. filtrationthen filtered
10. washThe resin was washed with 10% acetic acid/methanol
11. customthe washings then evaporated under reduced pressure
12. customdried under high vacuum
13. dissolutionThe residue was dissolved in methanol (50 ml)
14. waittetrahydrofuran (50 ml) and saturated aqueous sodium hydroxide solution (2 ml), left for 30 min
15. addition2M hydrochloric acid (50 ml) added
16. customthe organics evaporated under reduced pressure
17. extractionThe residual aqueous layer was extracted with ethylacetate
18. customthe organics separated, dried
19. customevaporated under reduced pressure, yield 5.05 g

ORD record

ord-110c3cd14f7b4ac79ddafe7b8bdc086f

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08158820B2