Trifluoroacetic acid → Ethyl (E)-4,4-difluoropent-2-enoate

Ethyl 4,4-difluoro-3-hydroxy-pentanoate (3.39 g, 0.0186 mol) was dissolved in THF (20 ml). Diphenyl-2-pyridylphosphin (7.37 g, 0.028 mol) was added followed after five minutes by di-tertbutylazodicarboxylate (2.83 g, 0.028 mol). The mixture was stirred for one hour at room temperature and left standing overnight. The mixture was acidified with trifluoroacetic acid (2 ml) and stirred for one hour at room temperature. The solvent was removed under reduced pressure and the residue partitioned between ethyl acetate and 4N HCl. The phases were separated, the organic phase was washed with 1M HCl (4×), dried over magnesium sulfate and evaporated to dryness. After distillation at 2 mbar 5.99 g were obtained which still contained some solvent but were used directly in the next step.

1. waitleft
2. waitstanding overnight
3. stirringstirred for one hour at room temperature
4. customThe solvent was removed under reduced pressure
5. customthe residue partitioned between ethyl acetate and 4N HCl
6. customThe phases were separated
7. washthe organic phase was washed with 1M HCl (4×)
8. dry with materialdried over magnesium sulfate
9. customevaporated to dryness
10. distillationAfter distillation at 2 mbar 5.99 g
11. customwere obtained which

ORD record

ord-e363edf0b495443188c45d13131d9031

Source dataset

uspto-grants-2016_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09260441B2