5-{Allyloxycarbonyl-[3-eth-(E)-ylidene-4-methyl-5-oxo-pyrrolidin-(2E)-ylidene]-methyl}-3-(2-methoxycarbonyl-ethyl)-4-methyl-1H-pyrrole-2-carboxylic acid tert-butyl ester

5-{Benzyloxycarbonyl-[3-eth-(E)-ylidene-4-methyl-5-oxo-pyrrolidin-(2Z)-ylidene]-methyl}-3-(2-methoxycarbonyl-ethyl)-4-methyl-1H-pyrrole-2-carboxylic acid tert-butyl ester

5-[carboxy-(3-ethylidene-4-methyl-5-oxo-pyrrolidin-2-ylidene)-methyl]-3-(2-methoxycarbonyl-ethyl)-4-methyl-pyrrole-2-carboxylic acid tert-butyl ester