Continuous flow synthesis of some 6- and 1,6-substituted-4-methyl-3-cyano-2-pyridones

In this paper six 6- and 1,6-substituted-4-methyl-3-cyano-2-pyridones were synthetized in a continuous flow microreactor system. Synthesis was done at room temperature and the obtained results were compared to those achieved within classical synthesis. In order to optimize the continuous flow syntheses and increase the yield of the products, the retention time in the microreactor was varied by changing flow rates of the reactant solutions. Furthermore, the reaction was optimized for 4,6-dimethyl-3-cyano-2-pyridone and 6-hydroxy-4-methil-3-cyano-2-pyridone which are commercially impor­tant in the pharmaceutical and dye industry. Both 2-pyridones were obtained in satisfactory yield of circa 60 % in less than 10 minutes. The resulting compounds were characterized by melting points, FT-IR, 1 H NMR and UV-Vis spectra. The efficiency of the presented method for the synthesis of 2-pyridone based molecules has promising potential for industrial production.