Design and synthesis of new 1,2,4-triazole derivatives containing morpholine moiety as antimicrobial agents

2-Morpholine-4ylethyl-3H -1,2,4-triazole-3-ones (2a, 2b) were obtained from the condensation between the corresponding ethoxycarbonylhydrazones and 2-morpholinoethanamine. 2a was converted to acetohydrazide (4) via the formation of an ester derivative (3). Treatment of 2a and 2b with several arylsulfonyl chlorides afforded the corresponding 2-arylsulfonyl-1,2,4-triazole-3-ones (5a-c and 6). The reaction of hydrazide (4) with benzyl iso- and benzyl isothiocyanate produced the corresponding carboxamide (8a) and carbothioamide (8b). The basic treatment of 8b yielded 5-mercapto-4H-1,2,4- triazol-3- yl)methyl]-2,4-dihydro-3H -1,2,4-triazol-3-one (10). The synthesis of 1,3-thiazol-2(3H) -ylidene -1,2,4-triazol- 1-ylacetohydrazide (11) and 1,3-oxazole-2(3H) -ylidene-1,2,4-triazole-1-yl)acetohydrazide (9) derivatives was performed from the reaction of 8a and 8b with substituted phenacyl bromides. All the newly synthesized compounds were screened for their antimicrobial activities and some of them were found to possess good or moderate antimicrobial activity.