An original route to the rare 8H-thiazolo [5, 4-f] quinazolin-9-one 1 and the novel 7H-thiazolo [4, 5-h] quinazolin-6-one 2 is described. Access to the regioisomers was realized by fusion of a thiazole and a quinazoline ring via Appel's salt chemistry. Thermal reactions were carried out using a focused microwave reactor, reducing the overall time of the multi-step synthesis.
