Comparison of crystal structures of 4-(benzo[b]thio­phen-2-yl)-5-(3,4,5-tri­meth­oxy­phen­yl)-2H-1,2,3-triazole and 4-(benzo[b]thio­phen-2-yl)-2-methyl-5-(3,4,5-tri­meth­oxy­phen­yl)-2H-1,2,3-triazole

The title compound, C(19)H(17)N(3)O(3)S (I), was prepared by a [3 + 2]cyclo­addition azide condensation reaction using sodium azide and l-proline as a Lewis base catalyst. N-Methyl­ation of compound (I) using CH(3)I gave compound (II), C(20)H(19)N(3)O(3)S. The benzo­thio­phene ring systems in (I) and (II) are almost planar, with r.m.s deviations from the mean plane = 0.0205 (14) in (I) and 0.016 (2) Å in (II). In (I) and (II), the triazole rings make dihedral angles of 32.68 (5) and 10.43 (8)°, respectively, with the mean planes of the benzo­thio­phene ring systems. The trimeth­oxy phenyl rings make dihedral angles with the benzo­thio­phene rings of 38.48 (4) in (I) and 60.43 (5)° in (II). In the crystal of (I), the mol­ecules are linked into chains by N—H⋯O hydrogen bonds with R (2) (1)(5) ring motifs. After the N-methyl­ation of structure (I), no hydrogen-bonding inter­actions were observed for structure (II). The crystal structure of (II) has a minor component of disorder that corresponds to a 180° flip of the benzo­thio­phene ring system [occupancy ratio 0.9363 (14):0.0637 (14)].