Microwave-assisted new conversion of friedländer reaction based on o-aminocyanopyrazole and cyclohexanone

To investigate the reaction of o-aminocyanopyrazole and cyclohexanone under microwave irradiation, 5-amino-4-cyano-1-phenylpyrazole and cyclohexanone were dispersed in different solvents, promoted by Lewis acid catalysts, and reacted in Biotage microwave reactor for different time and temperature. Incorporated with the normal Friedlander cyclocondensed compound, 1H-quinolino-[3, 4-b]-pyrazole, new product 1H-pyrazolo[3, 4-d]pyrimidin-4(5H)-one was conveniently synthesized under microwave irradiation via new conversion of Friedlander annulation like using traditional heating. All the new products were characterized by IR, MS, ¹H NMR, ¹³C NMR and elemental analysis. The study indicated that heating with microwaves versus, compared with classical conditions, show higher yielding, and was cleaner and faster.