Synthesis and NMR Spectroscopic Characteristics of Novel Polysubstituted Quinolines Incorporating Furoxan Moiety

Abstract

carbaldehyde (2) were synthesized. The condensation of 1 with some nitrobenzaldehydes catalyzed by acetic acid under mild conditions gave four styrylquinolines (1a-d). The condensation of 2 with methyl phenyl ketones catalyzed by potassium hydroxide at room temperature afforded six polysubstituted α,β-unsaturated ketones (2a-f). All proton and carbon signals of obtained compounds were assigned based on analyzing the spin-spin splitting patterns and on the cross peaks in their HSQC and HMBC spectra. ROESY spectrum analysis showed that for (E)-3-(quinolin-2-yl)-1-phenylprop-2-en-1-ones Hα resonated in a weaker field as compared to Hβ.Quinolines have long attracted attention owing to their significant biological and pharmacological properties such as antimalarial, 1,2 antituberculosis, 3-5 antibacterial, 6,7 and anticancer. 8,9 Thus, quinoline ring is considered a core pharmacophore in the design of many drugs such as antimalarial chloroquine, mefloquine and primaquine, 10 antituberculosis bedaquiline, 11 and other diarylquinolines. 12 The increasing resistance against many antibiotic drugs has forced chemists to develop synthetic strategies toward novel biologically active molecules. A strategy that has attracted considerable attention in current medicinal chemistry is based on the conjugation of two biologically active molecules into one hybrid compound. In recent years several classes of quinoline based structural hybrids of various bioactive heterocycles as potential antimicrobial agents have yielded promising results in primary biological evaluation. [13][14][15][16] The