Crystal structure of ethyl 6-methyl-4-oxo-1,4-dihydroquinoline-3- carboxylate, C13H13NO3

Abstract

(Equation presentation)(Table presentation) Source of material Diethyl{[(4-methylphenyl)amino]methylidene}propanedioate (1.0 g, 0.003 mol) and Dowtherm (10 mL) were heated to 250 C for 5 h. The reactionmixture was then cooled to 25 C and stirred in n-hexane (10 mL) for 10 min. The solid product obtained was filtered, dried and recrystallized from ethanol. Single crystals suitable for the X-ray diffraction study were grown by slow evaporation of a diluted ethanol solution of the compound at room temperature, yield: 0.79 g (95.1 %) [8]. Discussion Heterocyclic derivatives attract the interest ofmedicinal chemists because of their varied biological activities such as their anti-microbial [1] or analgesic [2] properties. Particularily intriguing are quinoline and its derivatives as these have already found application as anticancer [3], antiviral [4] and antimalarial [5] agents. In view of the biological importance as well as possible pharmacological applications, the title compound was synthesized to study its crystal structure. Although the title compound could be present in an aromatic form spanning the whole core of themolecule (i.e. as ethyl 4-hydroxy-6-methylquinoline-3-carboxylate), a tautomer featuring only an aromatic system on the non-heterocyclic ring is observed in the solid state. The least-squares planes defined by the respective intracyclic atoms of each of the two sixmembered rings enclose an angle of just 1.41(11) . The leastsquares plane defined by all non-hydrogen atoms of the aza-naphthalene core is essentially flat (r.m.s. of all fitted atoms = 0.015 ) with the carbon atom bearing the ester substituent deviatingmost from the plane (by 0.026(2) ). The hydrogen atom of the secondary amine group forms a hydrogen bond to the two doublebonded oxygen atom of the ester group. In terms of graph-set analysis [6, 7], the descriptor for the N-H Otype hydrogen bond necessitates a C1 1(6). In total, the molecules are connected to chains along the b direction. (Table presentation).