Dendrimer-encapsulated phosphotubngestic acid naoparticles immobilized on nanosilica: A mild, reusable and highly efficient heterogeneous catalyst for the synthesis of 14-aryl or alkyl-14-Hdibenzo[ a,j]xanthenes

A simple and environmentally benign procedure for the synthesis of 14- alkyl- or aryl-14H dibenzo[a,j]xanthenes is described through a one-pot condensation of β-naphthol with aryl or alkyl aldehydes in the presence of dendrimer-encapsulated phosphotungstic acid nanoparticles immobilized on nanosilica (Dendrimer-PWAn) as a catalyst under solvent-free conditions. This new procedure has notable advantages such as operational simplicity, excellent yields, short reaction time, and absence of any tedious workup or purification. In addition, the excellent catalytic performance under solvent-free conditions and the easy preparation and thermal stability of the catalyst make it a good heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst can be easily recovered and reused for seven consecutive reaction cycles without significant loss of activity.

dendrimer-PWAn, xanthene derivatives, multicomponent reactions, solvent-free conditions, green synthesis, heterogeneous catalyst