Facile Synthesis of Symmetric and Unsymmetric 1,3,4‐Oxadiazoles Using 2‐Acyl(or aroyl)pyridazin‐3‐ones.

Abstract

Oxadiazole derivatives Oxadiazole derivatives R 0290Facile Synthesis of Symmetric and Unsymmetric 1,3,4-Oxadiazoles Using 2-Acyl(or aroyl)pyridazin-3-ones. -The use of BF 3 ·OEt 2 instead of PPA also allows the preparation of symmetrical products (II). However, the yields are decreased and a longer reaction time is required. -(PARK

Synthesis, Cytotoxicity and Antimicrobial Evaluation of Some New 2-Aryl,5-Substituted 1,3,4-Oxadiazoles and 1,3,4-Thiadiazoles

“…The recent methodologies for preparation of 2,5-disubstituted-1,3,4-oxadiazoles include oxidative cyclization of aroyl/acyl hydrazones using catalytic Fe(III)/TEMPO [30], IBX/TEAB [31], catalytic Cu(OTf) 2 [32], and stoichiometric molecular I 2 [33]; cyclization of acylhydrazines using PPA or BF 3 ·OEt 2 and others [34][35][36]. The one-pot methodologies include synthesis from aryltetrazoles using DTBP/DCE, by dehydrative cyclization of ethyl carbazate and N-acylbenzotriazoles using Ph 3 P-I 2 [37], and three-component reaction of isocyaniminotriphenyl-phosphorane, aldehyde, and benzoic acid under mild conditions [38].…”

Facile Method for the Conversion of Semicarbazones/Thiosemicarbazones into Azines (Under Microwave Irradiation) and Oxadiazoles (by Grinding)

“…In continuation of our synthetic studies on heterocycles [1] and related methodology, [2] and in view of the biological importance of the oxadiazole system, [3][4][5][6] we are interested in synthesizing the 2-amino-5-aryl-1,3,4-oxadiazole for possible incorporation in the imidazole ring for an entry into novel purine derivatives. [7] Various methods are reported in the literature for the oxidation of acyl hydrazones as well as semicarbazones to 1,3,4-oxadiazoles with various oxidizing agents, [8] including sodium hypobromite, iodine-potassium iodide in aqueous sodium carbonate, and lead tetraacetate, and by electrochemical oxidation.…”