p-Bromochlorobenzene → Tert-butyl 4-(4-chlorophenyl)-4-hydroxy-3-methylpiperidine-1-carboxylate

Temperature

-78 °C

A solution of 1-bromo-4-chlorobenzene (9.24 g, 48.2 mmol) in anhydrous THF (100 mL) was cooled to −78° C. and treated dropwise with 1.6 M n-butyllithium in hexanes (28.7 mL, 46.0 mmol). The mixture was stirred at −78° C. for 45 minutes, during which time a precipitate was observed, then the slurry was treated dropwise with a solution of tert-butyl 3-methyl-4-oxopiperidine-1-carboxylate (4.9 g, 22.98 mmol) in anhydrous THF (50 mL). The reaction was stirred at −78° C. for 2 hours, then allowed to slowly warm to −20° C. and quenched with saturated ammonium chloride. The layers were separated, and the organic phase was concentrated in vacuo. The aqueous phase was extracted once with ethyl acetate (300 mL), and the organic phase was combined with the residue from the original organic phase. The mixture was washed 3× with water, and once with brine, then dried over sodium sulfate and concentrated in vacuo. The residue was digested in boiling hexanes (100 mL) for 1 hour, then the mixture was cooled to room temperature. The solids were collected by filtration, rinsed with a small amount of hot hexanes, and dried under vacuum to yield the title compound (6.25 g, 19.18 mmol, 83% yield) as a white powder. MS (ESI+)=252.2 (M−tert-BuO)+.

1. stirringThe reaction was stirred at −78° C. for 2 hours
2. temperatureto slowly warm to −20° C.
3. customquenched with saturated ammonium chloride
4. customThe layers were separated
5. concentrationthe organic phase was concentrated in vacuo
6. extractionThe aqueous phase was extracted once with ethyl acetate (300 mL)
7. washThe mixture was washed 3× with water
8. dry with materialonce with brine, then dried over sodium sulfate
9. concentrationconcentrated in vacuo
10. customfor 1 hour
11. temperaturethe mixture was cooled to room temperature
12. filtrationThe solids were collected by filtration
13. washrinsed with a small amount of hot hexanes
14. customdried under vacuum

ORD record

ord-4f63968c1093414e95a2fb7cfb2fb50c

Source dataset

uspto-grants-2013_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08501782B2