Synthesis of biologically active 1'-(2-oxo-2H-benzopyran-6-yl)- 5'-hydroxy-2'-methylindole-3'-amido-2"-phenyl-thiazolidene-4"-ones

6-Aminocoumarins on refluxing with ethyl acetoacetate in 1,2-dichloroethane gave two products: 3'-(2-oxo-2H-benzopyran-6-yl-amino)-but-2'-enoic acid ethyl ester 2a-c and N-(-2-oxo-2H-benzopyran-6-yl)-3'-oxo-butyramide 3a-c. Compounds 2a-c on treatment with 1,4-benzoquinone in N2-atmosphere yielded 1'-( 2-oxo-2H-benzopyran-6-yl)-5'-hydroxy-2'-methyl-3'-carbethoxyindoles 4a-c, which on further treatment with hydrazine hydrate gave 1'-(2-oxo-2H-benzopyran-6-yl)-5'-hydroxy-2'-methylindole-3'-acid hydrazides 5a-c. These acid hydrazides were treated with benzaldehyde to give 1'-(2-oxo-2H-benzopyran-6-yl)-5'-hydroxy-2'-methylindole-3'-benzylidene hydrazides 6a-c, which on further treatment with mercaptoacetic acid in 1,4-dioxane yielded 1'-(2-oxo-2H-benzopyran-6-yl)-5'-hydroxy-2'-methylindole-3'-amido-2"-phenylthiazolidene-4"-ones 7a-c. The structures of the compounds have been established on the basis of spectral and analytical data. All compounds have been screened for their antimicrobial activity and have been found to exhibit significant antibacterial and antifungal activities.