De-jiang Li, Feijun Dan, Heqing Fu
2008
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Journal
Heterocyclic Communications
Abstract
Dimethyl terephthalate (1) was reacted with 80% hydrazine hydrate in refluxing methanol for 12 h to afford terephthalate dihydrazide (2). Condensation of 2 with aromatic aldehydes afforded corresponding hydrazones 3a-3j. Cyclization of 3a3j with acetic anhydride in refluxing for 4-5 h afforded bis-l,3,4-oxadiazoline derivatives(4a-4j). The structures of 4a-4j were characterized by elementary analyses, IR, *H NMR, and MS spectroscopy. The preliminary antibacterial tests showed that most of them were effective against S.aureus. Introduction Oxadiazoline derivatives are found to possess significant biological activities such as antifungal (1), insecticidal (2), CNS depressant (3-5), anticonvulsant effects and growth accelerator for plant. They are highly important heterocyclic compounds, and have been used in research and development of agrochemicals and pharmaceutical chemistry. Most of those compounds only contain one 1,3,4-oxadiazoline unit in one molecule. As part of our current studies on the synthesis of the biologically active 1, 3, 4-oxadiazoline derivatives, we now report an efficient synthesis the compounds combining two 1,3,4-oxadiazoline rings in one framwork by cyclization of corresponding hydrazones 3a-3j with acetic anhydride, respectively. The synthesis, characterization and the results of antibacterial activities screening studies of the newly synthesized compounds are presented in this paper. Result and discussion The synthetic route is depicted in Scheme-1. Dimethyl terephthalate (1) was reacted with 80% hydrazine hydrate in refluxing methanol for 12 h to give terephthalic dihydrazide (2). Condensation of 2 with aromatic aldehydes afforded corresponding hydrazones 3a-3j. Cyclization of 3a-3j with acetic anhydride in refluxing for 4-5 h gave the title compounds 4a-4j (Table-1). Thin layer chromatography was employed to follow the progress of the above reactions. Vol. 14, No. 6, 2008 Synthesis and Antibacterial Activities of Bis-1,3,4-oxadiazoline