3-ethylidene-1-(4-methoxy-benzyl)-pyrrolidine-2,5-dione

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