Synthesis and In Vitro Antibacterial Evaluation of Novel Imidazo[2′, 1′:5, 1]‐1, 2, 4‐triazolo[4, 3‐c]‐quinazoline Derivatives of 5‐Thioxo‐1, 2, 4‐triazole, 4‐Oxothiazolidine, and their Open‐chain Counterparts
2003; Wiley; Volume: 336; Issue: 12 Linguagem: Inglês
10.1002/ardp.200300809
ISSN1521-4184
AutoresMagda N.A. Nasr, Magdy M. Gineinah, Eman R. El‐Bendary,
Tópico(s)Phenothiazines and Benzothiazines Synthesis and Activities
ResumoAbstract Two novel series of imidazo[2′, 1′:5, 1]‐1, 2, 4‐triazolo[4, 3‐c]quinazolines bearing 5‐thioxo‐1, 2, 4‐triazoles, 6a — f , and 4‐oxothiazolidines, 7a — f , were synthesized from corresponding thiosemicarbazide derivatives, 5a — f . The stepwise methodology applied to the preparation of compounds 5a — f was initiated with reaction of the parent 3‐amino‐1, 2, 4‐triazolo[4, 3‐c]quinazolines, 2 , with ethyl 2‐chloroacetoacetate resulting in annelation of the imidazole ring to give esters, 3a — c . However, hydrazinolysis of these ester derivatives gave the corresponding acid hydrazides, 4a — c , which on reaction with the appropriate alkyl isothiocyanate yielded compounds 5a — f . In turn, compounds 5 , were cyclized with potassium hydroxide or with ethyl bromoacetate to give the corresponding thioxotriazoles 6 and oxothiazolidines 7 , respectively. All synthesized compounds were screened for their in vitro antibacterial activity against various Gram‐positive and Gram‐negative bacteria. Some test compounds were found to possess potent antibacterial activities. Compound, 7f , exhibited much higher potency than the reference standard ciprofloxacin, against both types of bacteria, particularly, Gram‐positive organisms.
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