Synthesis and Spectral Study of Novel Benzopyrone and Quinolinone Derivatives

Abstract

A series of novel benzopyrones and quinolinone derivatives were prepared using the readily obtainable 6-nitrobenzo-2-pyron-3-carboxylate through the reaction with nitrogen nucleophilic reagents such as cyclohexyl amine, p-aminoacetophenone, diamines, hydrazine hydrate, thiosemicarbazide, anthranilic acid and carbon nucleophile as malononitrile. The IR, 1 H NMR and mass spectra of the new synthesised compounds were discussed.The coumarin nucleus is widely available from plants and is an important class of oxygen heterocycle. 1-3 The useful medical properties associated with these naturally occurring coumarins have lead to the investigation of several synthetic analogues. A large number of compounds containing coumarin have been investigated because of their anti-inflammatory 4 , antibacterial 5 , vasorelaxant 6 , antihepatitis-C virus agent 7 and antiproliferative activities 8 . In view of this, and as continuation of our effort 9-15 to identify new, potent, selective and less toxic antimicrobial agents, we aimed to synthesise a new coumarin derivative that exhibits high therapeutic activity. Results and discussionNitration of 3-carboethoxy coumarin in HNO 3 /AcOH mixture afforded 3-carboethoxy-6-nitrocoumarin 1 as the sole product (one spot in the TLC). The structure of 1 was characterised by its analytical and spectroscopic data (IR, 1 H NMR, MS). Thus, the IR spectrum of 1 showed sharp bands at 1736 cm −1 (ν C=O of α,β-unsaturated δ-lactone), 1706 cm −1 (ν C=O of ester group). However, 1 H NMR spectrum of 1 in CDCl 3 showed the following absorptions from low to high field: δ (ppm) 7.89-7.2 (m, 4H arom. + olefinic C 4 -H), 4.2 (q, 2H, CH 2 CH 3 , J = 6.7 Hz) and 1.2 (t, 3H, CH 2 CH 3 , J = 6.7 Hz).