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