Diisopropylamine → 1-(5-Bromo-2-fluorophenyl)-2,2-difluoroethanone

Temperature

-10 °C

A solution of diisopropylamine (12.7 g, 17.9 ml, 126 mmol) in tetrahydrofuran (375 ml) was cooled to −78° C. and n-butyllithium (1.6 M in hexane) (78.6 ml, 126 mmol) was added dropwise. After stirring for 10 minutes commercially available 1-bromo-4-fluorobenzene {CAS[460-00-4]} (20 g, 12.4 ml, 114 mmol) was added dropwise at max. −60° C. Stirring was continued at −70° C. for 2.5 hours. Then ethyl difluoroacetate (17.0 g, 13.7 ml, 137 mmol) was added dropwise. The mixture was warmed to −10° C. and then quenched by pouring the mixture onto 1 M hydrochloric acid. The mixture was extracted twice with ethyl acetate, dried over sodium sulphate, filtered and evaporated to give a yellow liquid (34 g; 118%). The residue was purified by chromatography on 200 g silica gel with a 3:1-mixture of cyclohexane and ethyl acetate as the eluent to give 1-(5-bromo-2-fluorophenyl)-2,2-difluoroethanone (26.5 g, 91.6% yield) as a yellow liquid. MS (EI): m/z=252.0 [M]+ and 254.0 [M+2]+.

1. additionwas added dropwise at max
2. custom−60° C
3. customquenched
4. additionby pouring the mixture onto 1 M hydrochloric acid
5. extractionThe mixture was extracted twice with ethyl acetate
6. dry with materialdried over sodium sulphate
7. filtrationfiltered
8. customevaporated
9. customto give a yellow liquid (34 g; 118%)
10. customThe residue was purified by chromatography on 200 g silica gel with a 3

ORD record

ord-9e6af7e588dc475193c4ec3b8d7a3922

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08785436B2