The Use of 3-Benzylidene Phthalide as Precursor to Synthesize New 1,3,4-Oxadiazole Derivatives

K. Younis, Shaymaa

doi:10.33899/rjs.2011.6507

	The Use of 3-Benzylidene Phthalide as Precursor to Synthesize New 1,3,4-Oxadiazole Derivatives
Rafidain Journal of Science
Article 6, Volume 22, Issue 5, 2011, Pages 62-75 PDF (0 K)
DOI: 10.33899/rjs.2011.6507
Author
Shaymaa K. Younis
Abstract
A series of new 2,5-disubstituted 1,3,4-oxadiazoles represented by compounds 2-phenyl-1-(2-(5-(5-aryl-1,3,4-oxadiazol-2-yl amino)-4H-1,2,4-triazol-3-yl)phenyl)ethanone (5a-f) have been synthesized from(Z)-3-benzylidene phthalide as useful precursor. 3-Benzylidene phthalide was reacted, firstly with urea under microwave irradiation and dry conditions to afford the corresponding 1-(2-(α-phenylacetyl)benzoyl)urea (1). The later compound underwent cycloaddition reaction with hydrazine hydrate (80%) to give 1-(2-(5-amino-4H-1,2,4-triazol-3-yl)phenyl)-2-phenylethanone (2), which upon reaction with ethyl chloroformate provided the corresponding ethyl- 5-(2-(α-phenylacetyl)phenyl)-4H-1,2,4-triazol-3-yl carbamate (3). 4-(5-(2-(α-Phenylacetyl)phenyl)-4H-1,2,4-triazol-3-yl) semicarbazide (4) was also prepared from the reaction of compound (3) with hydrazine hydrate (80%) under mild conditions. Finally, 2-phenyl-1-(2-(5-(5-aryl-1,3,4-oxadiazol-2-yl amino)-4H-1,2,4-triazole-3-yl)phenyl) ethanone (5a-f) were obtained via the reaction of compound (4) with various substituted benzoic acid by the action of phosphorous oxychloride. The structure of the prepared compounds were confirmed by the available physical and spectral methods
Keywords
benzylidene phthalide; oxadiazole derivatives; Triazole; Semicarbazide

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