Halothane → 1,1,1-Trifluoro-2-bromo-2-chloro-5-methyl-4-hexen-3-ol

Temperature

-78 °C

Sodium t-butoxide (1.39 g of a 42% solution in dry dimethyl formamide was added dropwise over a period of 5 minutes to a stirred mixture of 1-bromo-1-chloro-2,2,2-trifluoroethane (0.535 ml), 3-methylbut-1-en-1-al (0.538 ml) and dry tetrahydrofuran (10 ml) maintained at a temperature of -78° C. by external cooling under a nitrogen atmosphere. The mixture was then stirred for a further 40 minutes at the temperature after which the external cooling was removed and the reaction quenched by the dropwise addition of saturated aqueous ammonium chloride solution. The mixture was then partitioned between water and diisopropyl ether and the aqueous phase separated, washed with diisopropyl ether (3×25 ml), and the washings combined with the organic phase. The organic phase was washed with brine and dried over anhydrous sodium sulphate and concentrated by evaporation under reduced pressure. After purification by a procedure similar to that set out in the previous Example there was obtained 5-bromo-5-chloro-4-hydroxy-2-methyl-6,6,6-trifluorohex-2-ene (1.39 g), identified by nuclear magnetic resonance and infra-red spectroscopy.

1. temperatureby external cooling under a nitrogen atmosphere
2. temperatureexternal cooling
3. customwas removed
4. customthe reaction quenched by the dropwise addition of saturated aqueous ammonium chloride solution
5. customThe mixture was then partitioned between water and diisopropyl ether
6. customthe aqueous phase separated
7. washwashed with diisopropyl ether (3×25 ml)
8. washThe organic phase was washed with brine
9. dry with materialdried over anhydrous sodium sulphate
10. concentrationconcentrated by evaporation under reduced pressure
11. customAfter purification by a procedure similar to

ORD record

ord-e8deb101489c4e02b8ab82ed05f8e3e0

Source dataset

uspto-grants-1998_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05731475