17O-labeling studies on the reaction of 4-benzoyl-5-phenylfuran-2,3-dione with carbodiimides☆☆☆

Abstract The reactions of 4-benzoyl-5-phenyl-furan-2,3-dione 1 with isopropyl-phenylcarbodiimide as well as dimethylcarbodiimide are investigated with aid of 17 O-labeling experiments. From comparing the distribution of the label within starting materials and products, an unusual furandione rearrangement is disclosed. This rearrangement can be regarded as a peculiar variation of the well known nucleophilic substitution at a vinylic carbon.