Sustainable advancement to the synthesis of oxadiazoles

Abstract

In recent decades, a large number of reports related to synthesis of oxadiazoles appeared owing to a wide variety of their biological activity and industrial applications (usage as dyes, photosensitive, and electrical materials). The common synthetic approaches to oxadiazoles involve the use of carboxylic acids, acid chlorides, acyl hydrazides, diacyl hydrizides, semicarbazides, thoisemicarbazides, nitriles, aminoximes, etc. as a starting substrate. A variety of reaction conditions influence the cyclization reaction. Typically the reaction is promoted by heat and anhydrous reagents including thionyl chloride, phosphorus oxychloride, phosphorus pentaoxide, and many others. In recent years, reports concerning the synthesis of oxadiazoles under solvent - free, reactants immobilized on solid support and microwave irradiation condition have appeared. The present chapter mainly reports the design and synthesis of environmentally benign methods of 1,3,4- and 1,2,4-oxadiazoles and their application aspects. In each section, an elaborate description of a variety of examples from recent literature for the green synthetic approaches and applicability of substituted oxadiazoles are included.