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
