Comparison of crystal structures of 4-(benzo[b]thio-phen-2-yl)-5-(3,4,5-tri-meth-oxy-phen-yl)-2H-1,2,3-triazole and 4-(benzo[b]thio-phen-2-yl)-2-methyl-5-(3,4,5-tri-meth-oxy-phen-yl)-2H-1,2,3-triazole

Crystal structure and Hirshfeld surface analysis of 1-(2-fluoro-phen-yl)-1H-tetra-zole-5(4H)-thione

In the crystal of the title compound, C7H5FN4S, the mol-ecules are non-planar, with dihedral angle formed by least-squares planes of tetra-zole and benzene rings of 59.94 (8) °. The crystal packing is formed by N-H⋯S hydrogen bonds, which link the mol-ecules into centrosymmetric dimers with an R 2 2(8) ring motif, and by the offset face-to-face π-π stacking inter-actions between the benzene rings, which join the dimers into layers parallel to (100). The Hirshfeld surface analysis shows that the most important contributions to the surface contacts are from N⋯H/H⋯N (21.9%), S⋯H/H⋯S (21.1%), H⋯H (14.6%), F⋯H/H⋯F (11.8%) and C⋯H/H⋯C (9.5%) inter-actions.

Crystal structures of (Z)-5-[2-(benzo[b]thio-phen-2-yl)-1-(3,5-di-meth-oxy-phen-yl)ethen-yl]-1H-tetra-zole and (Z)-5-[2-(benzo[b]thio-phen-3-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)ethen-yl]-1H-tetra-zole

(Z)-5-[2-(Benzo[b]thio-phen-2-yl)-1-(3,5-di-meth-oxy-phen-yl)ethen-yl]-1H-tetrazole methanol monosolvate, C19H16N4O2S·CH3OH, (I), was prepared by the reaction of (Z)-3-(benzo[b]thio-phen-2-yl)-2-(3,5-di-meth-oxy-phen-yl)acrylo-nitrile with tri-butyl-tin azide via a [3 + 2]cyclo-addition azide condensation reaction. The structurally related compound (Z)-5-[2-(benzo[b]thio-phen-3-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)ethen-yl]-1H-tetra-zole, C20H18N4O3S, (II), was prepared by the reaction of (Z)-3-(benzo[b]thio-phen-3-yl)-2-(3,4,5-tri-meth-oxy-phen-yl)acrylo-nitrile with tri-butyl-tin azide. Crystals of (I) have two mol-ecules in the asymmetric unit (Z' = 2), whereas crystals of (II) have Z' = 1. The benzo-thio-phene 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 tetra-zole rings of (I) and (II) make dihedral angles with the mean planes of the benzo-thio-phene rings of 88.81 (13) and 88.92 (13)° in (I), and 60.94 (6)° in (II). The di-meth-oxy-phenyl and tri-meth-oxy-phenyl rings make dihedral angles with the benzo-thio-phene rings of 23.91 (8) and 24.99 (8)° in (I) and 84.47 (3)° in (II). In both structures, mol-ecules are linked into hydrogen-bonded chains. In (I), these chains involve both tetra-zole and methanol, and are parallel to the b axis. In (II), mol-ecules are linked into chains parallel to the a axis by N-H⋯N hydrogen bonds between adjacent tetra-zole rings.

Synthesis and biological evaluation of novel 4,5-disubstituted 2H-1,2,3-triazoles as cis-constrained analogues of combretastatin A-4

A series of combretastatin A-4 (CA-4) analogues have been prepared from (Z)-substituted diarylacrylonitriles (1a-1p) obtained in a two-step synthesis from appropriate arylaldehydes and acrylonitriles. The resulting 4,5-disubstituted 2H-1,2,3-triazoles were evaluated for their anti-cancer activities against a panel of 60 human cancer cell lines. The diarylacrylonitrile analogue 2l exhibited the most potent anti-cancer activity in the screening studies, with GI₅₀ values of <10 nM against almost all the cell lines in the human cancer cell panel and TGI values of <10 nM against cancer cell lines SF-539, MDA-MB-435, OVCAR-3 and A498. Furthermore, in silico docking studies of compounds 2l, 2e and 2h within the active site of tubulin were carried out in order to rationalize the mechanism of the anti-cancer properties of these compounds. From the in silico studies, compound 2e was predicted to have better affinity for the colchicine binding site on tubulin compared to compounds 2l and 2h. Analogue 2e was also evaluated for its anti-cancer activity by colony formation assay against 9LSF rat gliosarcoma cells and afforded an LD₅₀ of 7.5 nM. A cell cycle redistribution assay using analogue 2e was conducted to further understand the mechanism of action of these CA-4 analogues. From this study, analogues 2e and 2l were the most potent anti-cancer agents in this structural class, and were considered lead compounds for further development as anti-cancer drugs.

Synthesis and anti-cancer screening of novel heterocyclic-(2H)-1,2,3-triazoles as potential anti-cancer agents

trans-Cyanocombretastatin A-4 (trans-CA-4) analogues have been structurally modified to afford their more stable CA-4-(2H)-1,2,3-triazole analogues. Fifteen novel, stable 4-heteroaryl-5-aryl-(2H)-1,2,3-triazole CA-4 analogues (8a-i, 9 and 11a-e) were evaluated for anti-cancer activity against a panel of 60 human cancer cell lines. These analogues displayed potent cytotoxic activity against both hematological and solid tumor cell lines with GI50 values in the low nanomolar range. The most potent compound, 8a, was a benzothiophen-2-yl analogue that incorporated a 3,4,5-trimethoxyphenyl moiety connected to the (2H)-1,2,3-triazole ring system. Compound 8a exhibited GI50 values of <10 nM against 80% of the cancer cell lines in the panel. Three triazole analogues, 8a, 8b and 8g, showed particularly potent growth inhibition against the triple negative Hs578T breast cancer cell line with GI50 values of 10.3 nM, 66.5 nM and 20.3 nM, respectively. Molecular docking studies suggest that these compounds bind to the same hydrophobic pocket at the interface of α- and β-tubulin that is occupied by colchicine and cis-CA-4, and are stabilized by Van der Waals' interactions with surrounding amino acid residues. Compound 8a was found to inhibit tubulin polymerization in vitro with an IC50 value of 1.7 µM. The potent cytotoxicity of these novel compounds and their inhibition of tubulin dynamics make these triazole analogues promising candidates for development as anti-cancer drugs.