Efficient electrophilic fluorination of β-dicarbonyl compounds with the selectfluor reagent F-TEDA-BF 4 {1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)}

1,3-Dicarbonyl compounds (acyclic and cyclic 1,3-diketones, β-ketoesters, β-ketoamides) are converted efficiently to 2-monofluoro derivatives, and thence to 2,2-difluoro derivatives, with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate).