3-Cyclopentene-1,1-dicarboxylic acid,3,3'-(1E)-1,2-ethenediylbis[4-[(1E)-2-[4,4-bis[(1-methylethoxy)carbonyl]-2-(2-methyl-1-propen-1-yl)-1-cyclopenten-1-yl]ethenyl]-,1,1,1',1'-tetrakis(1-methylethyl) ester