One-pot three component isocyanide-based reaction: Synthesis of novel tetracyclic fused furo[2′,3′:4,5]pyrimido[2,1-b][1,3]benzothiazole

Abstract

A rapid, efficient and benign protocol has been developed for the construction of potentially biologically active furo[2′,3′:4,5]pyrimido[2,1-b][1,3]benzothiazole derivatives as major products along with (3E)-3-[(alkylamino)methylene]-2H-pyrimido[2,1-b][1,3]benzothiazole-2,4(3H)-dione derivatives as minor products using a one-pot, multi-component reaction of isocyanides, aromatic aldehydes and 2-hydroxy-4H-pyrimido[2,1-b][1,3]benzothiazol-4-one. The significant features of this protocol are the readily available and low-cost starting materials, short reaction time, mild reaction conditions, high yield of products and avoidance of toxic solvents and catalysts. Structures of compounds 4b and 5a were confirmed from single crystal X-ray studies.