Use of transesterified 1,3-diketoesters in the synthesis of trisubstituted pyrazoles and their biological screening
作者:N. J. Siddiqui、M. Idrees、N. T. Khati、M. G. Dhonde
DOI:10.4314/bcse.v27i1.9
日期:——
Starting from 2-acetylbenzofuran derivatives 1a-d, methyl/ethyl 4-substituted/unsubstituted benzofuran-2-yl)-2,4-dioxobutanoate 2a-d and 3a-d have been synthesized by Claisen’s condensation reaction with diethyloxalate. The transesterified product, 1,3-diketoester 2a-d on condensation with phenyl hydrazine undergo cyclization to afford the corresponding methyl 5-(substituted/unsubstituted benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carboxylate 4a-d, which upon further condensation with hydrazine hydrate yielded 5-(substituted/unsubstituted benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazide 5a-d. The structures of the newly synthesized compounds 2a-d, 3a-d, 4a-d and 5a-d were characterized by their elemental analysis and spectral studies such as IR, 1H NMR, 13C NMR and MS. All the synthesized compounds were screened for their antimicrobial activity. Most of the synthesized compounds showed high sensitivity against the selected bacteria and fungi at various concentrations.
从2-乙酰苯并呋喃衍生物1a-d出发,通过与二乙氧基草酸酯的克莱森缩合反应合成了甲基/乙基4-取代/未取代苯并呋喃-2-基)-2,4-二氧代丁酸酯2a-d和3a-d。转酯化产物1,3-二酮酯2a-d与苯肼缩合后发生环化,得到相应的甲基5-(取代/未取代苯并呋喃-2-基)-1-苯基-1H-吡唑-3-羧酸酯4a-d,进一步与水合肼缩合得到5-(取代/未取代苯并呋喃-2-基)-1-苯基-1H-吡唑-3-羟肼酸酯5a-d。这些新合成的化合物2a-d、3a-d、4a-d和5a-d的结构通过元素分析和红外光谱、1H NMR、13C NMR和质谱等光谱研究进行了表征。所有合成的化合物均进行了抗微生物活性筛选。大多数合成的化合物在不同浓度下对选定的细菌和真菌表现出较强的敏感性。