Cesium carbonate → Tert-butyl 5-chloro-4-(2-(4,4-difluorocyclohexyl)ethoxy)-2-fluorobenzoate

Temperature

0 °C

To a of solution ethyl 2-(4,4-difluorocyclohexyl)acetate (1.44 g, 7.00 mmol) in anhydrous tetrahydrofuran (23 mL) and anhydrous methanol (0.6 mL) was added lithium borohydride (4 M in tetrahydrofuran, 3.5 mL, 16.00 mmol) at 0° C. and the mixture was heated to reflux for 2 hours. The mixture was then cooled to 0° C. and quenched with methanol until gas evolution ceased. The solution was warmed to ambient temperature then poured into water (50 mL). The aqueous layer was separated and extracted with diethyl ether (3×20 mL). The combined organic layers were washed with brine; dried over anhydrous sodium sulfate, filtered and concentrated in vacuo to give the crude alcohol (0.98 g), which was dissolved in anhydrous dimethylsulfoxide (6 mL), tert-butyl 5-chloro-2,4-difluorobenzoate (1.64 g, 6.60 mmol) and cesium carbonate (4.11 g, 12.6 mmol) was added. The reaction mixture was heated at 70° C. for 2 hours and then cooled to ambient temperature and diluted with water (60 mL) and extracted with ethyl acetate (4×20 mL). The combined organic layers were washed with brine; dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography (0% to 10% ethyl acetate in hexanes) to afford the title compound (0.681 g, 29%): 1H NMR (300 MHz, CDCl3) δ 7.88 (d, J=7.7 Hz, 1H), 6.63 (d, J=12.1 Hz, 1H), 4.08 (t, J=6.6 Hz, 2H), 2.17-2.07 (m, 2H), 1.77-1.62 (m, 5H), 1.57 (s, 9H), 1.42-1.29 (m, 4H).

1. temperaturethe mixture was heated
2. temperatureto reflux for 2 hours
3. customquenched with methanol until gas evolution
4. temperatureThe solution was warmed to ambient temperature
5. additionthen poured into water (50 mL)
6. customThe aqueous layer was separated
7. extractionextracted with diethyl ether (3×20 mL)
8. washThe combined organic layers were washed with brine
9. dry with materialdried over anhydrous sodium sulfate
10. filtrationfiltered
11. concentrationconcentrated in vacuo
12. customto give the crude alcohol (0.98 g), which
13. temperatureThe reaction mixture was heated at 70° C. for 2 hours
14. temperaturecooled to ambient temperature
15. extractionextracted with ethyl acetate (4×20 mL)
16. washThe combined organic layers were washed with brine
17. dry with materialdried over anhydrous sodium sulfate
18. filtrationfiltered
19. concentrationconcentrated in vacuo
20. customThe residue was purified by column chromatography (0% to 10% ethyl acetate in hexanes)

ORD record

ord-68449667f48541c1a821455c8563875b

Source dataset

uspto-grants-2015_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08952169B2