applying green and highly efficient approach for a facile synthesis of new thiazoloquinoline, thiazolopyridine, and thiazolonaphthyridine derivatives

An eco-friendly approach for the synthesis of new thiazoloquinolines, thiazolopyridines, and thiazolonaphthyridines scaffolds has been achieved using α-enolicdithioesters, cysteamine, arylglyoxal monohydrate, and cyclic 1,3-diketones (dimedone, 4-hydroxycoumarin, and 4-hydroxy-1-methyl-2(1h)-quinolone) under thermal solvent-free conditions. the highlight of this protocol is the generation of two heterocyclic rings, using a domino, one-pot, four-component reaction. in producing heterocyclic rings first, a thiazole ring generated from the reaction of α-enolicdithioesters and cysteamine is achieved. second heterocyclic ring formed by the condensation of conjugated thiazole with the knoevenagel product achieved from arylglyoxal monohydrate and 1,3-diketones followed by an n-cyclization. catalyst- and solvent-free, short reaction times, high yields and a simple work-up make it an attractive protocol for the preparation of diversified thiazoloquinoline, thiazolopyridine, and thiazolonaphthyridine derivatives.