Direct Synthesis of Trichloro‐thiazolo[3,2‐ a ]pyrimidine and Thiazolo[2,3‐ b ]quinazoline Derivatives

An efficient one‐pot method for synthesis of new biologically active thiazolo[3,2‐ a ]pyrimidine and thiazolo[2,3‐ b ]quinazoline derivatives is described via reaction of pentachloropyridine with fused pyrimidine‐2(5 H )‐thiones or quinazoline‐2(1 H )‐thiones. These reactions were carried out in the presence of potassium carbonate as a base in acetonitrile as a solvent to produce products 3a – n in good‐to‐excellent yield. Pentachloropyridine is doubly electrophilic building blocks for the formation of ring annulated thiazolo[3,2‐ a ]pyrimidine and thiazolo[2,3‐ b ]quinazoline products.