(Z)-5-(3,4,5-Tri-meth-oxy-styr-yl)-2,3-di-hydro-thieno[3,4-b][1,4]dioxine

In the title compound, C17H18O5S, an analogue of the potent anti-cancer agent combretastatin A-4, the alkene C=C bond has a cis conformation and the C-C=C-C torsion angle is 9.0 (3)°. The dihedral angle between the benzene and thio-phene rings is 54.07 (4)°. The dioxene ring adopts a half-chair conformation, with the C atoms of the methyl-ene groups displaced by -0.325 (2) and 0.341 (3) Å from the plane of the other atoms. The C atoms of the two meta-meth-oxy groups are close to being coplanar with their attached benzene ring [displacements = -0.025 (2) and -0.196 (2) Å], whereas the C atom of the para-meth-oxy group is significantly displaced [by -1.107 (2) Å]. In the crystal, C-H⋯O hydrogen bonds link the mol-ecules into [0-11] chains, which feature two different types of R 2 (2)(6) loops.