Synthesis of Novel Fused Heterocycles Based on 6‐Amino‐4‐phenyl‐2‐thioxo‐1,2‐dihydropyridine‐3,5‐dicarbonitrile

Under phase transfer catalysis conditions, 6‐amino‐4‐phenyl‐2‐thioxo‐1,2‐dihydropyridine‐3,5‐dicarbonitrile ( 1 ) was allowed to react with halo compounds, acrylonitrile, chloroacetyl chloride, ethyl cyanoacetate, formamide, triethylorthoformate, or formic acid to give new derivatives of fused pyridines 2–22, respectively. Acetylation of compound 1 using acetic anhydride afforded product 23 , which in turn underwent intramolecular cyclization in pyridine to give the corresponding pyrido2,3‐d]pyrimidine 24 .