Design and synthesis of benzothiazole/thiophene-4H-chromene hybrids

Abstract

A library of 4H-chromene derivatives with heterocyclic substituent's at the 3 and 4-positions was synthesized in a convenient DBU catalysed three component synthesis between salicylaldehyde, acetonitrile derivatives and thiazolidinedione to afford 2-amino-3-benzothiazole-4-heterocycle-4H-chromenes and 2-amino-3-thiophenoyl-4-heterocycle-4H-chromenes derivatives in ethanol and a mixture of ethanol and water (1 : 1) at room temperature. The significance of this protocol is the feasibility of incorporating substituents simultaneously at the 3 and 4 positions of 4H-chromenes in an efficient three component reaction.