Nano SiO2-SO3H catalyzed one -pot condensation of β- naphthol, aldehydes and cyclic 1,3-dicarbonyl compounds

Xanthenes and benzoxanthenes are important heterocycles that are known to possess multiple biological activities. Although not widely found in nature, xanthenes and compounds based on these core templates exhibit a broad spectrum of pharmaceutical activitiessuch as anti-bacterial anti inflammatory [2], and anti-viral In addition, these compounds have been employed as dyes, and pH- sensitive fluorescent materials for visualization of biomolecular assemblies and utilized in laser technologies. Thus a broad utility range has made xanthenesprime synthetic candidates thereby accentuating the need to develop newer synthetic routes for scaffold manipulation of xanthene derivatives. The synthesis of tetrahydrobenzo α]xanthen-11-ones has been reported in the presence ofstrontium triflate and NaHSO4. SiO2 under reflux in halogenated solvents for long hours In this paper we report nano SiO2-SO3H can be used as a reusable catalysts for this conversion in solvent free condition