There are two molecules per asymmetric unit and the two ester groups have different orientations m each of them; the C=C-C=O torsion angles are 1.9 and 2.4(6)degrees for the groups remote from and 91.7 and -91.4(5)degrees for the groups adjacent to the 9-Me substituents. The remote ester groups are therefore fully conjugated with the C=C double bond [cos2(angle) = 1.0] and the adjacent groups non-conjugated [cos2(angle) = 0], presumably as a result of steric effects as in the 9-chloro derivative.