Hypervalent-Iodine-Mediated Ring-Contraction Monofluorination Affording Monofluorinated Five-Membered Ring-Fused Oxazolines.

The first ring-contraction monofluorination reaction mediated by a hypervalent iodine reagent is reported, and the use of the reaction for the synthesis of monofluorinated five-membered ring-fused oxazolines is described. By means of this reaction, a fluorine atom can be selectively introduced either on the five-membered ring or external to it, depending on whether or not the substrate has C-4 alkyl substituents. The reaction was used for the further conversion of probenecid and isoxepac.