3-(2-allyloxycarbonyl-ethyl)-5-[allyloxycarbonyl-(3-ethylidene-5-oxo-pyrrolidin-2-ylidene)-methyl]-4-methyl-1H-pyrrole-2-carboxylic acid tert-butyl ester

3-{5-[allyloxycarbonyl-(3-ethylidene-5-oxo-pyrrolidin-2-ylidene)-methyl]-2-formyl-4-methyl-1H-pyrrol-3-yl}-propionic acid allyl ester

3-{5-[allyloxycarbonyl-(4-ethyl-3-ethylidene-5-oxo-pyrrolidin-2-ylidene)-methyl]-2-formyl-4-methyl-1H-pyrrol-3-yl}-propionic acid allyl ester

4-ethylidene-5-thioxo-pyrrolidin-2-one