Lithium borohydride → HCID 9921628, compound

Temperature

-15 °C

Lithium borohydride (5.3 g, 0.24 mol) was suspended in THF (200 mL) under a nitrogen atmosphere and cooled to −15° C. with stirring. Methyl (2R)-3-(dibenzylamino)-2-fluoropropanoate (56.6 g, 0.19 mol) was suspended in THF (250 mL) and added dropwise to the mixture over 1 h; the internal temperature was maintained below −10° C. during the addition. On completion of addition, the reaction mixture was allowed to warm to room temperature and stirred at this temperature for 17 h. The reaction mixture was cooled to 0° C. and cautiously quenched with a saturated aqueous solution of ammonium chloride (300 mL). The reaction mixture was extracted with ethyl acetate (2×200 mL) and the organic phase was concentrated under reduced pressure. The crude residue was dissolved in 2 N hydrochloric acid (200 mL, pH=2 approx.) and the aqueous phase was washed with ether (2×200 mL). The aqueous phase was basified (pH=10 approx.) with 80% ammonium hydroxide in brine, extracted with ethyl acetate (3×200 mL), dried over anhydrous sodium sulfate (10 g), filtered and concentrated under reduced pressure to afford (2R)-3-(dibenzylamino)-2-fluoro-1-propanol (48 g, 93%) as a yellow oil.

1. additionadded dropwise to the mixture over 1 h
2. temperaturethe internal temperature was maintained below −10° C. during the addition
3. additionOn completion of addition
4. temperatureto warm to room temperature
5. stirringstirred at this temperature for 17 h
6. temperatureThe reaction mixture was cooled to 0° C.
7. customcautiously quenched with a saturated aqueous solution of ammonium chloride (300 mL)
8. extractionThe reaction mixture was extracted with ethyl acetate (2×200 mL)
9. concentrationthe organic phase was concentrated under reduced pressure
10. dissolutionThe crude residue was dissolved in 2 N hydrochloric acid (200 mL, pH=2 approx.)
11. washthe aqueous phase was washed with ether (2×200 mL)
12. extractionextracted with ethyl acetate (3×200 mL)
13. dry with materialdried over anhydrous sodium sulfate (10 g)
14. filtrationfiltered
15. concentrationconcentrated under reduced pressure

ORD record

ord-6b11f1466f1a4a939919abe1a7fa94e2

Source dataset

uspto-grants-2005_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06841698B2