Regioselective reaction: synthesis and pharmacological study of Mannich bases containing ibuprofen moiety.

A series of 4-[(4-aryl)methylidene]amino-2-(substituted-4-ylmethyl)-5-{1-[4-(2-methylpropyl)phenyl]ethyl}-2,4-dihydro-3H-1,2,4-triazole-3-thione (6) were synthesized from an arylpropionic acid namely, ibuprofen by a three-component Mannich reaction. Aminomethylation of 4-[(4-aryl)methylidene]amino-5-{1-[4-(2-methylpropyl)phenyl] ethyl}-4H-1,2,4-triazole-3-thiol (5) with formaldehyde and a secondary amine furnished this novel series of Mannich bases (6). Both Schiff bases (5) and Mannich bases (6) were well characterized on the basis of IR, NMR, mass spectral data and elemental analysis. They were screened for their anti-inflammatory, analgesic, antibacterial and antifungal activities. Some of the Mannich bases (6) carrying morpholino and N-methylpiperazino residues were found to be promising anti-inflammatory and analgesic agents.

4-Chloro-N'-[(Z)-4-nitro-benzyl-idene]benzohydrazide monohydrate.

In the title compound, C(14)H(10)ClN(3)O(3)·H(2)O, the benzohydrazide group is not planar and the mol-ecule exists in a cis configuration with respect to the methyl-idene unit. The dihedral angle between the two substituted benzene rings is 38.7 (3)°. In the crystal structure, mol-ecules are linked by O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds into a two-dimensional network parallel to the (100) plane. The crystal structure is further stabilized by weak C-H⋯O inter-actions.

[3-(4-Chloro-phen-yl)-5-hydr-oxy-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl](3-pyrid-yl)methanone.

In the title compound, C(21)H(16)ClN(3)O(2), the dihedral angles formed by the pyrazole ring with the pyridyl, phenyl-ene and phenyl rings are 6.80 (5), 9.23 (5) and 74.96 (5)°, respectively. The phenyl and phenyl-ene rings are inclined at 80.14 (2)°. Intra-molecular O-H⋯O and C-H⋯N hydrogen bonds generate S(6) ring motifs. The crystal packing is strengthened by short inter-molecular O-H⋯N, C-H⋯O hydrogen bonds and π-π stacking inter-actions with centroid-centroid distances of 3.6247 (5)-3.7205 (5) Å, together with inter-molecular short O⋯N contacts [2.7682 (11) Å]. Mol-ecules are linked into infinite chains along [100].

Ethyl 4-(4-methoxy-phen-yl)-2-oxo-6-phenyl-cyclo-hex-3-ene-1-carboxyl-ate.

The asymmetric unit of the title compound, C(22)H(22)O(4), consists of two independent mol-ecules (A and B) which differ significantly in the orientations of ethyl carboxyl-ate groups. The phenyl ring in mol-ecule B is disordered over two orientations with occupancies of 0.55 (2) and 0.45 (2). The cyclo-hexenone ring of both mol-ecules adopts an envelope conformation. The dihedral angle between the two aromatic rings is 81.12 (7)° in mol-ecule A and 70.8 (3)° in mol-ecule B [57.5 (4)° in the minor disorder component]. The crystal structure is stabilized by weak intermolecular C-H⋯O hydrogen bonds and C-H⋯π inter-actions.

rac-2-Bromo-3-eth-oxy-1,3-bis-(4-methoxy-phen-yl)propan-1-one.

In the racemic (S,S/R,R) title compound, C(19)H(21)BrO(4), the two benzene rings are almost coplanar to each other, forming a dihedral angle of 3.58 (10)°. The crystal packing is strengthened by inter-molecular Br-O [2.9800 (16) Å] short contacts, which link the molecules into infinite one-dimensional chains along [001].

3-Benzamidomethyl-4-[(E)-2-chloro-benzyl-ideneamino]-1H-1,2,4-triazole-5(4H)-thione.

In the title compound, C(17)H(14)ClN(5)OS, the dihedral angles formed by the two benzene rings with the triazole ring are 66.88 (3) and 19.16 (3)°, and the benzene rings are inclined to each other with a dihedral angle of 78.40 (3)°. Inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into layers parallel to the (100) planes, and centrosymmetric π-π stacking inter-actions [centroid-centroid distance = 3.7717 (5) Å] are formed between benzene rings in neighbouring layers.