A microwave-assisted and heteropolyacids-catalysed cyclocondensation reaction for the synthesis of 4(3H)-quinazolinones

We have investigated a microwave - assisted synthesis of 4(3H)-quinazolinones by condensation of anthranilic acid, orthoesters (or formic acid) and substituted anilines, using Keggin-type heteropolyacids (H3PW12O40 center dot 13H(2)O, H4SiW12O40 center dot 13H(2)O, H4SiMo12O40 center dot 13H(2)O or H3PMo12O40 center dot 13H(2)O) as catalysts. We found that the the use of H3PW12O40 center dot 13H(2)O acid coupled to microwave irradiation allows a solvent-free, rapid (similar to 13 min) and high-yielding reaction.