The synthesis of new heterocyclic compounds

Synthesis of Pyran derivatives have been attracted considerable interest because especially, naphthopyran compounds possess various biological activities such as antimicrobial, antitumor and antifungal. A variety of naphthopyran derivatives have been isolated and identified as natural phytochemicals. Furthermore, these compounds can be used as dyes, in laser technologics and as pH sensitive fluorescent materials for visualization of biomolecules.Various methods have been reported for the synthesis of these compounds, cyclodehidration, ?-alkilation on heteroatoms, the cyclocondensation reaction of 2-hydroxyaromatic aldehydes with 2-tetralone. However, these methods suffer from one or more disadvantages such as a long reaction time, low yield, use of toxic solvents, requirement of excess of reagent/cataylsts, laborious workup procedures, and hash reaction conditions.In recent years, one-pot, multicomponent method has been became one of the most important aspects in Organic Chemistry. Nevertheles rare earth metal triflates as catalysts were developed as a new type of lewis acid were widely applied in organic synthesis due to their low toxicity, high stability, ease of handling, water tolerance and recoverability from water.In this study, new naphthopyran compounds have been synthezied through a one-pot condensation of various substitued aromatic aldehydes with 2-naphthol and 1,3-dion compounds in the presence of triflate as a catalyst.The structures of the obtained new compounds have been clarified by spectroscopic methods such as, FTIR, 1H NMR, 13C NMR, GC-MS.