The preferred conformations of three N-ethoxycarbonyl derivatives of r-2,c-7-diphenylhexahydro-1,4-diazepin-5-ones 9-11 have been studied using NMR spectral techniques. The N(1),N(4)-bis(ethoxycarbonyl)-r-2,c-7-diphenylhexahydro-1,4-diazepin-5-ones 9 and 10 were found to prefer flattened boat conformations with fast equilibrium between two N-CO rotamers while 4-(ethoxycarbonyl)-t-3-isopropyl-r-2,c-7-diphenylhexahydro-1,4-diazepin-5-one (11) was found to prefer a chair conformation with the N-COOEt group locked in one rotameric state. Dynamic (1)H NMR studies have been carried out on the N(1),N(4)-bis(ethoxycarbonyl) derivatives 9 and 10, and the barriers for the N-CO rotation were found to be 49.9 and 58.0 kJ mol(-1), respectively. These barriers are much lower than those observed for N-nitroso- and N-formyl-r-2,c-7-diphenylhexahydro-1,4-diazepin-5-ones (90.0 and 84.4 kJ mol(-1), respectively), indicating a fast equilibrium in 9 and 10 at room temperature.

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Synthesis and Antimicrobial Activity of Novel 1,5-Benzodiazepines. -The title compounds (III) are obtained by CdCl2-catalyzed reaction of acetoacetanilides with o-phenylenediamine under conventional heating as well as microwave irradiation conditions. The antimicrobial screening of the compounds shows that compound (IIId) exhibits excellent activity against S. aureus and compound (IIIe) is active against C. albicans. -(ILANGO, S. S.; REMYA, P. U.; PONNUSWAMY*, S.; Indian J.

In the title compound, C14H19ClN2O, the diazepine ring adopts a boat conformation. The Cl atom of the chloro­acetyl group is trans to the N atom of the diazepine ring. In the crystal, the mol­ecules form chains running along the diagonal of the ac plane through N—H⋯O hydrogen bonds.

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