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‐2H‐chromeno[2,3‐d]pyrimidine‐4,5(1H,3H)‐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.