Design and synthesis of new naphtho[2,1-$b$]pyrano [2,3-$d$]pyrimidinones under classical and microwave conditions

A fast and efficient method for the synthesis of naphthopyranopyrimidinones derivatives in excellent yields was developed through cyclocondensation reaction between previously prepared pyrimidinic hydrazides and some electrophilic species such as 2,4-pentanedione, 2,5-hexanedione, cyclic anhydrides, and phenylthioisocyanate under microwave irradiation. Compared to the conventional methods applied, it was found that better yields and shorter reaction times were achieved using microwave-assisted synthesis. Structures of all synthesized compounds were established on the basis of spectroscopic methods including $^{1}$H NMR, $^{13}$C NMR, and HRMS-ES.