Synthesis of New Coumarin Derivatives as Antibacterial Agents

3-[(2'-Substituted benzylidene amino thiazol-4'-yl) amino] coumarins (5a-5d) and 3-[(2'-Substitutd benzylidine amino oxazole-4'-yl) amino coumarins (8a-8d) were prepared by the reaction with compounds 4 and 7 respectively with various substituted aldehydes in the presence of glacial acetic acid. All the synthesized compounds 120 have been screened for their antibacterial and antifungal activities and compared with reference drugs ciprofloxacin, gattifloxocin, luconazole. Key wordsCoumarins, thiazole, oxazole, azetidinone, antibacterial and antifungal activities. Introduction Coumarin derivatives are important source of heterocyclic compounds of pharmocological interest, as they shown a wide spectrum of biological activity viz antibacterial antifungal, herbicidal and antitumour activities. Furthermore it has been reported by different scientists that coumarin derivatives incorporating thiazole, azetidinone 8 and oxazole ring were also found to possess interesting antibacterial and antifngal activities. In the light of these observation several new coumarin derivatives possessing thiazole, oxazole and -lactum ring will be synthesized with the hope to possess better antibacterial agents. Compound 9c 3-[2{4-methoxy phenyl-3"-chloro 4"-oxoazetidin-1"-yl) oxazol-4'-yl} amino] coumarin was found to be most potent antibacterial compound against E. coli and K. pneumoniae and compound 9d was found to be most potent antifungal agents against C. albicans. The structure of all the compound were established on the bases of IR and H NMR. Material & Methods The melting points of the compounds were determined in open glass capillaries with the help of thermonic melting point apparatus and are uncorrected. The homogeneity of all the newly synthesized compounds was routinely checked by thin layer chromatography (TLC) on silica gel G plates. The IR spectra were recorded on a Beckman Acuulab-10. Spectrometer (ν max in cm) and the H NMR spectra were recorded by Brucker DPX-300MHz using CDCl3 as solvent. Synthesis of 3-Acetylamino-coumarin (1) It was prepared according to the method by Tripathy and Mukerjee. To the suspension of aceturic acid (0.005 mol) in dry benzene (25 mL) containing triethylamine (0.0125 mol), benzenesulphonyl chloride (0.005 mol) was added and the mixture was shaken at room temperature untill the aceturic acid crystal disappeared and triethylamine salt separated out which were filtered and washed with benzene (10 mL). To the benzene filtrate salicyladehyde (0.005 mol) was added. The mixture refluxed for 2 h. After refluxing the solution was concentrated upto dryness and the residue obtained was treated with a groups ethanol and filtered. The separated solid was recrytallized from aqueous ethanol. Physical and analytical data are given in table-1. Ashok Kumar et al /Int.J. ChemTech Res.2010,2(3) 1746 Table-I Physical and analytical data of compounds 1 to 20