Crystal structures of (Z)-5-[2-(benzo[b]thiophen-2-yl)-1-(3,5-dimethoxyphenyl)ethenyl]-1H-tetrazole and (Z)-5-[2-(benzo[b]thiophen-3-yl)-1-(3,4,5-trimethoxyphenyl)ethenyl]-1H-tetrazole

Abstract

(Z)-5-[2-(Benzo[b]thiophen-2-yl)-1-(3,5-dimethoxyphenyl)ethenyl]-1H-tetrazole methanol monosolvate, C19H16N4O2S·CH3OH, (I), was prepared by the reaction of (Z)-3-(benzo[b]thiophen-2-yl)-2-(3,5-dimethoxyphenyl)acrylonitrile with tributyltin azide via a [3 + 2]cycloaddition azide condensation reaction. The structurally related compound (Z)-5-[2-(benzo[b]thiophen-3-yl)-1-(3,4,5-trimethoxyphenyl)ethenyl]-1H-tetrazole, C20H18N4O3S, (II), was prepared by the reaction of (Z)-3-(benzo[b]thiophen-3-yl)-2-(3,4,5-trimethoxyphenyl)acrylonitrile with tributyltin azide. Crystals of (I) have two molecules in the asymmetric unit (Z′ = 2), whereas crystals of (II) have Z′ = 1. The benzothiophene rings in (I) and (II) are almost planar, with r.m.s deviations from the mean plane of 0.0084 and 0.0037 Å in (I) and 0.0084 Å in (II). The tetrazole rings of (I) and (II) make dihedral angles with the mean planes of the benzothiophene rings of 88.81 (13) and 88.92 (13)° in (I), and 60.94 (6)° in (II). The dimethoxyphenyl and trimethoxyphenyl rings make dihedral angles with the benzothiophene rings of 23.91 (8) and 24.99 (8)° in (I) and 84.47 (3)° in (II). In both structures, molecules are linked into hydrogen-bonded chains. In (I), these chains involve both tetrazole and methanol, and are parallel to the b axis. In (II), molecules are linked into chains parallel to the a axis by N—H...N hydrogen bonds between adjacent tetrazole rings.

Keywords

• crystal structure
• 5-substituted-1H-tetrazoles
• tetrazole-tethered combretastatin A-4 analogs
• anticancer agents
• hydrogen bonding