(Diethylamino)sulfur trifluoride → 1,4-Dibenzyl-2-(fluoromethyl)piperazine

Temperature

-78 °C

(1,4-Dibenzylpiperazin-2-yl)methanol (15 g, 50.5 mmol) in DCM (50 mL) was added dropwise to a stirred solution of DAST (7.42 mL, 60.6 mmol) in DCM (150 mL) cooled to −78° C. The reaction mixture was maintained below −30° C. for 24 h before warming to room temperature and stirring for an additional 20 h. The reaction was quenched by the addition of water (100 mL). The organic phase was separated, the aqueous basified with NaOH (aq.) to pH 10 and extracted with DCM (3×75 mL). The combined organics were washed with water (2×100 mL), brine (2×100 mL), dried (Na2SO4) and concentrated under reduced pressure. The resultant oil was purified by chromatography on silica gel with EtOAc:heptane (1:9, v/v) as eluent to afford 1,4-dibenzyl-2-fluoromethylpiperazine (6.0 g, 20.1 mmol, 40%). A biproduct of the reaction was also isolated, 1,4-dibenzyl-6-fluoroperhydro-1,4-diazepine (1.0 g, 3.35 mmol, 7%).

1. temperatureThe reaction mixture was maintained below −30° C. for 24 h
2. temperaturebefore warming to room temperature
3. customThe reaction was quenched by the addition of water (100 mL)
4. customThe organic phase was separated
5. extractionextracted with DCM (3×75 mL)
6. washThe combined organics were washed with water (2×100 mL), brine (2×100 mL)
7. dry with materialdried (Na2SO4)
8. concentrationconcentrated under reduced pressure
9. customThe resultant oil was purified by chromatography on silica gel with EtOAc:heptane (1:9, v/v) as eluent

ORD record

ord-c074c48f39ec4938a83c1f9a55474c83

Source dataset

uspto-grants-2010_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07820649B2