The stilbene derivative 1,2,3-trimethoxy-4-[(E)-2-phenylvinyl]benzene, C(17)H(18)O(3), (I), and its homocoupling co-product (E,E)-1,4-bis(2,3,4-trimethoxyphenyl)buta-1,3-diene, C(22)H(26)O(6), (II), both have double bonds in trans conformations in their conjugated linkages. In the structure of stilbene (I), the aromatic rings deviate significantly from coplanarity, in contrast with coproduct (II), the core of which is rigorously planar. The deviation in stilbene (I) seems to be driven by intermolecular electrostatic interactions. Diene (II) sits on a crystallographic inversion centre, which bisects the conjugated linkage.