Convenient synthesis of benzo[b]pyrazolo[5,1-f][1,6]naphthyridines by silver triflate catalyzed three-component reaction of 2-alkynyl-3-formylquinolines, tosylhydrazine and carbonyl compounds

Benzo[b]pyrazolo[5,1-f][1,6]naphthyridines were prepared by silver triflate catalyzed one-pot cyclization of tosylhydrazine, carbonyl compounds and 2-alkynyl-3-formylquinolines, which are available by Sonogashira reaction of 2-chloro-3-formylquinoline.