A novel one pot route to flavones under dual catalysis, an organo- and a Lewis acid catalyst

Substituted phenylacetylenes react with various o-hydroxy aromatic aldehydes under dual catalysis of piperidine and FeCl3 in refluxing toluene to yield flavones in good to excellent yield. Atmospheric oxygen acts as stoichiometric oxidant in the process. Some of these compounds had been recently reported to show fair insecticidal activity against Spodoptera frugiperda.