Microwave-assisted, sequential four-component synthesis of polysubstituted 5,6-dihydroquinazolinones from acyclic precursors and a mild, halogenation-initiated method for their aromatization under focused microwave irradiation

Abstract

A one-pot, microwave-assisted protocol has been developed for the synthesis of 5,6-dihydroquinazolinones that incorporate structural fragments from chalcones, acetylacetoacetate, ammonium formate and formamide. This process generates two rings, two carbon–carbon and three carbon–nitrogen bonds and does not require the use of chromatographic purification. The dihydroquinazolinones were efficiently aromatized without the need for metal-based oxidants by a microwave-assisted halogenation–elimination sequence in the presence of N-bromosuccinimide, again in the absence of chromatographic purification.