Introduction of a new member of bipyridine-based molten salt containingcopper as an efficient and reusable catalyst for the synthesis of isoxazolederivatives

Isoxazoles constitute a crucial class of heterocyclic compounds composed of five-memberedrings, with one oxygen and one nitrogen atom located in adjacent positions. The distinctivestructural motif of isoxazole confers diverse non-covalent interactions. The transformations oftheir derivatives encompass electrophilic substitution reactions, nucleophilic substitution, as wellas side-chain substitution reactions in isoxazoles.Also hold particular significance, exhibiting adiverse range of biological activities and therapeutic potential. Specifically, isoxazole hasdemonstrated promising anticancer, antituberculosis, anti-inflammatory, and acetylcholinesteraseinhibitory properties in pharmaceutical applications. [۱,۲]One of the uses methods forit preparation of isoxazoles is the reaction between aromaticaldehyde, hydroxylamine, and ethyl acetoacetate, which is carried out in a water solvent and inthe presence of an acid catalyst.[۳]In this work, a novel approach utilizing a Lewis acidic moltensalt based on bipyridine was employed for the synthesis of isoxazole derivatives(Scheme۱).Thepreparation of this catalyst is uncomplicated. Moreover, use of this catalyst presents variousbenefits such as effortless and facile separation, considerable product yield, and brief reactiontime.