Synthesis of A New Series of N-Substituted-3-Indolyl-Heterocycles for Antimicrobial Evaluation


 CLAISEN-SCHMIDT reaction of N-ethyl (1a), N-benzyl (1b), N- .......benzoyl (1c), N-methylsulphonyl (1d) and N-benzenesulphonyl-3-acetylindoles (1e) with benzaldehyde gave 1-(N-substituted-1H-indol-3-yl)-3-phenyl-prop-2-ene-1-ones(2a-e). Cyclocondensation of 2a-e with urea, thiourea or guanidine led to the formation of pyrimidine derivatives 3a-e -5a-e, respectively. Base catalyzed reaction of 2a-e with ethyl acetoacetate gave cyclohexanone derivatives 6a-e, which were reacted with hydrazine hydrate to afford the indazole derivatives 7a-e. On the other hand, reaction of 2a-c with some hydrazine derivatives namely, hydrazine hydrate, acetyl hydrazine, phenyl hydrazine and benzyl hydrazine hydrochloride yielded the pyrazole derivatives 8a-c–11a-c, respectively. Moreover, reaction of 2a-c with hydroxyl amine hydrochloride gave the isoxazole derivatives 12a-c. The newly synthesized compounds were tested for their antimicrobial activity and the results revealed that, 4-(N-benzyl-1H-indol-3-yl)-6-phenyl-pyrimidin-2-amine (5b) showed potent growth inhibition activity at a concentration of 20 and 10 μg against Candida albicans (ATCC 10231) compared to reference drug cycloheximide.