Two biologically active thiophene-3-carboxamide derivatives.

The compounds 2-[[(E)-(4-methoxyphenyl)methylene]amino]-N-(3-methylphenyl)-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide, C24H24N2O2S, (I), and N-(4-methylphenyl)-2-[[(E)-(4-methylphenyl)methylene]amino]-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide, C24H24N2OS, (II), show antibacterial and antifungal activities. The m-toluidine ring in (I) and the p-toluidine ring in (II) are coplanar with their respective thiophene rings. In (I), an intermolecular C-H...O hydrogen bond is present, whereas (II) does not exhibit any significant intermolecular interactions. However, in both compounds, an intramolecular N-H.N hydrogen bond forms a pseudo-six-membered ring, thus locking the molecular conformation and eliminating conformational flexibility.