Chemoselective Mono- and Difluorination of 1,3-Dicarbonyl Compounds

By
altering the amount of Selectfluor, the highly selective mono-
and difluorination of 1,3-dicarbonyl compounds has been achieved,
affording a variety of 2-fluoro- and 2,2-difluoro-1,3-dicarbonyl compounds
in good to excellent yields. The reaction can be readily performed
in aqueous media without any catalyst and base, which features practical
and convenient fluorination. Importantly, a gram-scale reaction, transformation
of 2-fluoro-1,3-diphenylpropane-1,3-dione to 4-fluoro-1,3,5-triphenyl-1H-pyrazole, and chlorination and bromination of 1,3-dicarbonyl
compounds are realized to further exhibit its synthetic utility.