Synthesis and characterization of the novel heteroannulated chromeno[2,3‐d]pyrimidines and chromeno[2,3‐d][1,3]thiazolo[3,2‐a] pyrimidines

Abstract 2‐Amino‐6,8‐dibromo‐7‐hydroxychromone‐3‐carboxamide ( 2 ) was synthesized and utilized as synthetic intermediate for the synthesis of novel heteroannulated chromones namely chromeno[2,3‐ d ]pyrimidines and chromeno[2,3‐ d ][1,3]thiazolo [3,2‐ a ]pyrimidines. Condensation of carboxamide 2 with formic acid, acetyl chloride, benzoyl chloride, isonicotinic acid, diethyl carbonate, and carbon disulfide furnished the novel chromeno[2,3‐ d ]pyrimidine derivatives, respectively. Reaction of 7,9‐dibromo‐8‐hydroxy‐2‐thioxo‐2 H ‐chromeno[2,3‐ d ]pyrimidine‐4,5(1 H ,3 H )‐dione ( 8 ) with some bielectrophilic reagents afforded the first known chromeno[2,3‐ d ] [1, 3] thiazolo[3,2‐ a ]pyrimidines, respectively. Spectral and analytical data confirmed the structures of the new synthesized products.