Multicomponent, solvent-free synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-one derivatives catalyzed by copper ferrite magnetic nanoparticles

Xanthenes and its derivatives are known as an important class of heterocyclic compounds widely used as leco-dye, in laser technology and pH sensitive fluorescent materials. Although not widely found in nature, xanthenes and compounds based on these core templates exhibit a broad spectrum of pharmaceutical activities. These compounds are also utilized as antagonists for paralyzing action of zoxazolamine and in photodynamic therapy. Thus a broad utility range has made xanthenes prime synthetic candidates thereby accentuating the need to develop newer synthetic routes for scaffold manipulation of xanthene derivatives. A few methods have been developed for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivatives. One-pot three-component condensation of aldehydes, 2-naphthol and cyclic 1,3-dicarbonyl compound is the most convenient method for the preparation of these compounds. In this context some methods and catalysts have been reported. However, these methodologies show varying degrees of success as well as limitations due to use of toxic organic solvents, expensive catalyst, prolonged reaction times, the requirement of special apparatus, or harsh reaction conditions. Thus, there is a certain need for the development of an alternative route for the production of these derivatives, which surpasses those limitations [1-4]. In this work, an efficient and direct protocol for the preparation of 12-aryl-8,9,10,12-tetrahydro-benzo[a] xanthen-11-one derivatives employing a three-component one-pot reaction of aryl aldehydes, 2-naphthol and dimedone in the presence of a catalytic amount of copper ferrite nanoparticles under solvent-free conditions is described (Scheme 1). High yields, ease of recovery, and reusable catalyst with consistent activity makes this protocol efficient and environmentally benign.