Addition of trifluoromethyltrimethylsilane to acyl phosphonates: synthesis of TMS-protected 1-alkyl-1-trifluoromethyl-1-hydroxyphosphonates and 1-aryldifluoroethenyl phosphates.
Addition reactions of nucleophilic CF3TMS to acyl phosphonates were investigated. Various acyl phosphonates reacted readily with CF3TMS in the presence of K2CO3 in DMF at rt to give 1-alkyl-2,2,2-trifluoro-1-trimethylsilyloxyethylphosphonate in 70-90% yields. When benzoyl phosphonates were used as starting material, after addition of CF3, the formed alcoholate undergoes phosphonate-phosphate rearrangement to form the acyl anion, followed by elimination of F- to give 1-aryldifluoroethenyl phosphates in 87-97% yields. As a representative example, vinylphosphate 6a was converted into 2,2-difluoro-1-phenylethanone 7 with 6 N HCl/EtOH/reflux or CAN/NaOH/MeOH/0 degrees C in 82-90% yields.
Demir
Ayhan S
AS
Department of Chemistry, Middle East Technical University, 06531 Ankara, Turkey. asdemir@metu.edu.tr
Eymur
Serkan
S
D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D015394:Molecular Structure; D063065:Organophosphonates / Q000138:chemical synthesis* / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D013237:Stereoisomerism
D006845:Hydrocarbons, Fluorinated; D063065:Organophosphonates; D012821:Silanes; C509472:trimethyl(trifluoromethyl)silane