FURTHER STUDIES ON THE SYNTHESIS OF α-FLUORO CARBONYL COMPOUNDS

Article abstract of DOI:10.1016/S0022-1139(00)80895-7

The trimethylsilyl enol ethers of cycloalkanones and acid esters are converted in high yields (70-90percent) to the corresponding α-fluoro carbonyl derivative using XeF2 in CH2Cl2.Non-cyclic α-hydroxy ketones such as ethyl mandelate are efficiently transformed to the α-fluoro product by DAST and by Ishikawa's reagent.Nucleophilic displacement of halogen by fluoride failed in cyclic systems, giving instead, α,β-unsaturated ketones in DMF or CH3CN (18-crown-6) and 1,2-diones in DMSO, with KF acting as a base.Attempts at DMSO oxidation of I(Br)F adducts failed to give the α-fluoro ketones, but resulted in dehydrohalogenation to the trans-vinyl fluorides.