APPLICATION OF FLUOROCARBETHOXY-SUBSTITUTED PHOSPHONATE: A FACILE ENTRY TO SUBSTITUTED 2-FLUORO-3-OXOESTERS

Abstract

Diethyl(fluorocarbethoxymethyl)phosphonate 1a or diisopropyl(fluorocarbethoxymethyl)phosphonate 1b, prepared from triethyl phosphite or triisopropyl phosphite with ethyl bromofluoroacetate, react with n-butyllithium in THF to give the corresponding phosphonate carbanions [(RO)₂P(O)CFCO₂Et]⁻Li⁺ 2a (R=Et) and 2b (R=i-Pr). Addition of trimethylsilyltrifluoroacetate CF₃C(O)OSiMe₃ to a THF solution of phosphonate carbanions formed the enolate of ethyl trifluoroacetylfluoroacetate [CF₃C(O)CFCO₂Et]⁻Li⁺ 3. Subsequent protonation, alkylation or allylation of the enolate afforded substituted 2,4,4,4-tetrafluoro-3-oxoesters CF₃C(O)CFR₁CO₂Et 10

Key Words:

• fluorophosphonate
• Michaelis-Arbuzov reaction
• enolate
• alkylation
• allylation
• 3-oxoesters