Environmentally Benign Synthesis of Isoxazole–5(4H)-one Derivative Using Cashew Shell Extract as a Natural Acid Catalyst

An effective, simple, and environmentally friendly methodology for the synthesis of isoxazole- 5-(4H)-one derivative has been introduced by using cashew shell extract as a natural acid catalyst. The key advantages of this protocol are the straightforward preparation of the extract from cashew shell waste and the simple reaction conditions. It offers heterocyclization with some interesting and promising features, such as a simple method of preparing cashew shell extract, a cost-effective methodology, a shorter reaction time, easy workup, easy separation of the product, mild conditions, and minimal waste. The synthesis of heterocyclic compounds containing the isoxazole structural unit is important, as many of these compounds and their derivatives exhibit biological activity.