Synthesis And Antibacterial Activities Of Pyrazole Amide Derivatives Bearing Indole Moiety

Heterocyclic compounds due to its good selectivity, high activity, less dosage, low toxicity and the physiological and biochemical reaction of the specific characteristics of pest become to an active research area. Heterocyclic compounds of pyrrole, pyrimidine, pyridine, imidazole, pyrazole and benzimidazole and indoles other a few compounds emerge out of some new landmark potions, and amide compounds because its has the characteristics of high efficiency, low toxicity, broad-spectrum favored by researchers, has become one of hotspots in the field of pesticide.In search of highly active and low toxic antibacterial agent, pyrazole and amide moieties were introduced into indole molecule using the method of biological principle, and synthesize a series of indole derivatives. The main work was summarized as follows:1. Indole as starting materials generate 3-acetyl indole by the Vilsmeier reaction and followed the condensation with diethyl oxalate, cyclization with hydrazine hydrate and hydrolysis to obtain the indole pyrazole formic acid. Finally, in the presence of condensing agent four series of indole pyrazole amide derivatives were synthesized. The structures of target compounds are shown as follows:2. All the target compounds were confirmed by 1H NMR, IR and elemental analysis. Different methods were used on the substitution of small molecule compounds, which optimized the synthetic condition for intermediates and target compounds and improved the synthesis yield. The synthetic methods of the target compounds were discussed and some experimental post-treatment were simplified, which makes the reaction economical and environmentally friendly. The characteristic absorption peaks of the target compounds were analyzed and discussed in details.3. In this paper, the antibacterial activities of the series of compounds against Escherichia coli and Staphylococcus aureus were tested by the colony counting method. Results showed that all the target compounds exhibited some antibacterial activities against Escherichia coli, the ratio of antibacterial activities was over 50% when the concentration is 80 μg/mL, the target compoundsⅠe,Ⅰi,Ⅰj, Ⅱb, Ⅱd and Ⅳc exhibited good activities against Escherichia coli with IC50 values of 6.22 μg/mL, 33.08 μg/mL, 7.65μg/mL, 24.22μg/mL and 21.87 μg/mL, which were significantly higher than that of levofloxacin hydrochloride. All the target compounds exhibited some antibacterial activities against Staphylococcus aureus, the ratio of antibacterial activities is over 40% when the concentration is 80 μg/mL, the target compoundsⅠi andⅡe exhibited good activities against Staphylococcus aureus with IC50 values of 21.55 and 28.05 μg/mL, which were significantly higher than that of levofloxacin hydrochloride.