Microwave-assisted annulation for the construction of pyrido-fused heterocycles and their application as photoluminescent chemosensors.

A catalyst-free microwave-assisted annulation protocol for the preparation of biologically interesting pyrido-fused quinazolinones and pyrido[1,2-]benzimidazoles is developed. This reaction involves the [3 + 3] annulation of various quinazolinones or benzimidazoles with 3-formylchromones to yield functionalized 11-pyrido[2,1-]quinazolin-11-one and pyrido[1,2-] benzimidazole derivatives. This approach is successfully extended to the construction of various pyrazolo[4,3-]pyrido[1,2-]pyrimidin-10(1)-ones.