A new acid-catalyzed rearrangement of oxiranes for the syntheses of biologically important pharmaceutical molecules with anthranilic acid and oxalamide moieties has been discovered.

The novel rearrangement of oxirane carboxamide derivatives proceeds through an one‐pot three‐step cascade sequence involving the classical Meinwald rearrangement with the formation of ketone bearing an active α‐methylene group, a transformation of the carbonyl group to the carboxylic functionality and finally a migration of the active α‐methylene group to the nitrogen atom of the reduced nitro group.