Abstract Acid catalyzed double rearrangement of the ethyl 6-oxa-2, 2, 4, 4-tetramethyl-1- azabicyclo [3, 1, 0] hexane-3-carboxylate leading to ethyl 1, 2, 4, 5-tetramethyl-pyrrole-3- carboxylate is proposed on the basis of identification of the intermediate ethyl 5-hydroxy-1, 2, 4, 4-tetramethylpyrroline-3-carboxylate.
