No abstract

The title compound, C 13 H 15 N 3 O 7 , crystallizes as two independent molecules which differ in their conformation. Intermolecular hydrogen bonding between the amide and carboxylic acid groups as NÐHÁ Á ÁO C interactions results in the formation of one-dimensional chains with NÁ Á ÁO distances of 2.967 (6) and 3.019 (6) A Ê. Neighbouring chains are linked by C OÁ Á ÁHÐO interactions to form a twodimensional network, with OÁ Á ÁO distances of 2.675 (6) and 2.778 (6) A Ê. Comment The study of biologically important molecules continues to be of primary importance in medicinal chemistry. Processes such as blood coagulation, hormone processing, viral replication and cancer-cell invasion are critically dependent on protease enzymes which are attractive target molecules in the design of speci®c and selective drugs. Important protease inhibitors are usually based on modi®ed amino acids incorporating structural features which determine normal enzyme-substrate recognition processes. Structure-based drug design strategies to identify interactions between a potential inhibitor and target receptor require accurate inhibitor structures. We are Experimental N-3,5-Dinitrobenzoyl-l-leucine was synthesized by the reaction of 3,5-dinitrobenzoyl chloride with the parent l-leucine. Recrystallization from ethanol/water afforded colourless plate-like crystals suitable for X-ray analysis [m.p. 451±453 K (uncorrected); literature