Synthesis of some novel ethyl 5-methyl-6-cyano-7-substituted-2-oxo-2H-pyrano [2, 3-b] pyridine-3-carboxylate derivatives

Ethyl 5-methyl-6-cyano-7-substituted-2-oxo-2H-pyrano[2, 3-b]pyridine-3-carboxylates 4a-j have been prepared starting from 2, 6-dihyroxy-3-cyano-4-methyl pyridine 1. The compound 1 reacts with N,N-dimethylaminoethylenemalonate in acetic acid under reflux conditions to give 5-methyl-6-cyano-7-hydroxy -2H-pyrano[2,3-b]pyridine-2-one 2, which is further treated with phosphorous oxychloride to obtain ethyl 5-methyl-6-cyano-7chloro-2-oxo-2H-pyrano[2,3-b]pyridine-3-carboxylate 3. This chloride derivative 3 is finally converted to various amino derivatives 4a-j by condensation with corresponding amines. These compounds are expected to have alntihypertensive activity.