Condensation of either 4-(benzothiazol-2-yl)phenylamine 1 or 4-amino-2-(benzothiazol-2-yl)-phenol 2 with ethyl cyanoethoxyacrylate or diethyl ethoxymethylenemalonate (EMME) followed by intra molecular thermal cyclisation results in substituted quinolones which upon alkylation then base-hydrolysis yielded the target compounds 6-(benzothiazol-2-yl)-1-alkyl-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (3a,b); 7-(benzothiazol-2-yl)-1-alkyl-4-oxo-1,4-dihydro-6-alkoxyquinoline-3-carboxylic acid (4a,b). Meanwhile diazotisation of 4-(benzothiazol-2-yl)phenylamine (1) followed by reaction with malononitrile then intra molecular Friedel-Crafts acylation gave 4-amino-6-(benzothiazol-2-yl)cinnoline-3-carbonitrlie 5. The antimicrobial activity of some of the target compounds using gram-positive microbes (Staphylococcus aureus and Bacillus subtilis) and gram-negative bacteria (‘Escherichia coli and Pseudomonas aeruginosa) is carried out and 6-(benzothiazol-2-yl)-1-alkyl-4-oxo-1,4-dihydro quinoline-3-carboxylic acid (3a,b) and 7-(benzothiazol-2-yl)-1-alkyl-4-oxo-1,4-dihydro-6-alkoxyquinoline-3-carboxylic acid (4a,b) showed promising activity.
将 4-(苯并噻唑-2-基)苯胺 1 或 4-氨基-2-(苯并噻唑-2-基)-苯酚 2 与氰乙氧基丙烯酸乙酯或乙氧基甲叉丙二酸二乙酯(EMME)进行缩合,然后进行分子内热环化,可得到取代的喹诺酮类化合物,经烷基化后再进行碱水解,可得到目标化合物 6-(苯并噻唑-2-基)-1-烷基-4-氧代-1、4-二氢喹啉-3-羧酸 (3a,b);7-(苯并噻唑-2-基)-1-烷基-4-氧代-1,4-二氢-6-烷氧基喹啉-3-羧酸(4a,b)。同时,4-(苯并噻唑-2-基)苯胺(1)重氮化后与丙二腈反应,然后进行分子内弗里德尔-卡夫斯酰化反应,得到 4-氨基-6-(苯并噻唑-2-基)噌啉-3-甲腈 5。利用革兰氏阳性微生物(金黄色葡萄球菌和枯草芽孢杆菌)和革兰氏阴性菌(大肠杆菌和绿脓杆菌)对一些目标化合物进行了抗菌活性研究,并得到了 6-(苯并噻唑-2-基)-1-烷基-4-氧代-1、喹啉-3-羧酸(3a,b)和 7-(苯并噻唑-2-基)-1-烷基-4-氧代-1,4-二氢-6-烷氧基喹啉-3-羧酸(4a,b)显示出良好的活性。