title: Silver-catalyzed tandem synthesis of naphthyridines and thienopyridines via three-component reaction.
abstract: An efficient approach for the silver-catalyzed regioselective tandem synthesis of highly functionalized 1,2-dihydrobenzo[1,6]naphthyridines 6a-z and 7a-e by the reaction of ortho-alkynylaldehydes 3a-n with amines 4a-d and ketones 5a-c/active methylene compounds 5d-g, under mild reaction conditions, is described. The scope of the developed chemistry was successfully extended for the direct synthesis of 1,2-dihydrobenzo[4,5]thieno[2,3-c]pyridines 8a-e, which is known as the sulfur analogue of β-carbolines. Naphthyridines 6a-z and thienopyridines 8a-e were obtained via dual activation concept using l-proline as organocatalyst; however, naphthyridines 7a-e were synthesized without using organocatalyst. The reaction shows selective N-C bond formation on the more electrophilic alkynyl carbon, resulting in the regioselective 6-endo-dig-cyclized products. Reactivity behavior of electron-deficient and electron-rich ortho-alkynylaldehydes in the synthesis of naphthyridines and thienopyridine by three-component reaction is supported by the control experiment.
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi, Delhi 110007, India. averma@acbr.du.ac.in
authors.forename: Akhilesh K
authors.initials: AK
authors.lastname: Verma
authors.forename: Siva K Reddy
authors.initials: SK
authors.lastname: Kotla
authors.forename: Deepak
authors.initials: D
authors.lastname: Choudhary
authors.forename: Monika
authors.initials: M
authors.lastname: Patel
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Tiwari
mesh_terms: D002384:Catalysis; D060326:Chemistry Techniques, Synthetic; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009287:Naphthyridines / Q000138:chemical synthesis* / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D058924:Thienopyridines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D009287:Naphthyridines; D058924:Thienopyridines; D012834:Silver