Abstract The title isoimides rearrange upon heating to the corresponding imides through a [1, 3] O⇀ N aroyl transfer. The reaction is slightly accelarated by electron withdrawing substituents in the migrating moiety and retarded by electron donating as it is suggested by the positive (+ 0.5) Hammett ϱ value. The mechanism operating is either a rate determining nucleophilic attack by the nitrogen lone pair on the carbonyl carbon or a sigmatropic [π2s+ ...
