Dimethoxycarbene, generated at 110 degrees C by thermolysis of imethox
y-5,5-dimethyl-Delta(3)-1,3,4-oxadiazoline, displaces fluoride from ar
omatic rings that are activated with electron-withdrawing groups. Inte
rmolecular substitution on Sanger's reagent and on hexafluorobenzene a
re reported together with intramolecular substitution by a dioxycarben
e with a tethered aryl group.