Two biologically active thiophene-3-carboxamide derivatives.

The two title compounds, 2-([(1Z)-[4-(dimethylamino)phenyl]methylene]amino)-4,5-dimethyl-N-(2-methylphenyl)thiophene-3-carboxamide, C(23)H(25)N(3)OS, (I), and 2-([(1E)-[4-(dimethylamino)phenyl]methylene]amino)-N-(4-methylphenyl)-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide,C(25)H(27)N(3)OS, (II), show antibacterial and antifungal activities. The asymmetric unit of (II) contains two crystallographically independent molecules. The o-toluidine ring in (I) lies gauche with respect to the thiophene ring. In (II), the p-toluidine ring is coplanar with the thiophene ring in one molecule, but is tilted from it in the other molecule. Neither structure exhibits any significant intermolecular interactions, but in both, an intramolecular N-H.N hydrogen bond forms a pseudo-six-membered ring, thus locking the molecular conformation and removing conformational flexibility.