Sulfamic acid-catalyzed multicomponent synthesis of 7-phenyl-7,12 dihydrobenzo(h)pyrido[2,3-b]naphthydrin-6(5H)-one derivatives: a green avenue

A series of novel 7-phenyl-7,12-dihydrobenzo( h )pyrido[2,3- b ]naphthydrin-6(5 H )-one were synthesized by a one-pot three-component condensation of 2,4-dihydroxyquinoline, 2-amino pyridine and various aromatic aldehydes with sulfamic acid as an enviro-economic catalyst. The salient features of this method consist of high atom economy and yields, short reaction time, non-carcinogenic solvents, and chromatography-free work-up procedure. Fascinatingly, the catalyst can be reused for up to four cycles giving good to excellent yields. By employing this method, a series of 14 pyrido[2,3- b ]naphthydrin compounds were synthesized. This procedure is projected as a green avenue in the combinatorial synthesis of biologically active naphthydrin derivatives. Graphical Abstract