Spirally twisted imidazolium iminyl ylide structures from 1,2-rearrangements in reactions of imidazolium dicyanomethanide 1,3-dipoles with maleic anhydride: new perspectives on the Boekelheide-Fedoruk ring expansions

The reactions of 1-substituted-imidazolium-3-dicyanomethanides with maleic anhydride gave new ylide products from a Michael reaction and 1,2-rearrangements. These experiments, combined with theoretical calculations, provide an interesting new perspective on the Boekelheide-Fedoruk ring expansions.