title: Synthesis of 5,6-Dihydrodibenzo[b,h][1,6]naphthyridines via Copper Bromide Catalyzed Intramolecular [4 + 2] Hetero-Diels-Alder Reactions.
abstract: A highly efficient synthesis of 5,6-dihydrodibenzo[b,h][1,6]naphthyridines was achieved by reaction between 2-(N-propargylamino)benzaldehydes and arylamines in the presence of CuBr2. The in situ generated electron-deficient heterodienes bearing a tethered alkyne partner underwent an intramolecular inverse electron-demand hetero-Diels-Alder reaction followed by air oxidation to furnish the products in high yields. This reaction tolerated a large number of substituents to afford diverse products under mild conditions. This strategy was also successfully extended to the synthesis of 12,13-dihydro-6H-benzo[h]chromeno[3,4-b][1,6]naphthyridin-6-ones starting from 3-amino-2H-chromen-2-one, again in high yields.
authors.affiliation: Organic Synthesis Group, Department of Chemistry, School of Chemical and Biotechnology, SASTRA University , Thanjavur 613401, Tamil Nadu, India.
authors.forename: Isravel
authors.initials: I
authors.lastname: Muthukrishnan
authors.affiliation: Organic Synthesis Group, Department of Chemistry, School of Chemical and Biotechnology, SASTRA University , Thanjavur 613401, Tamil Nadu, India.
authors.forename: Perumal
authors.initials: P
authors.lastname: Vinoth
authors.affiliation: Organic Synthesis Group, Department of Chemistry, School of Chemical and Biotechnology, SASTRA University , Thanjavur 613401, Tamil Nadu, India.
authors.forename: Thavaraj
authors.initials: T
authors.lastname: Vivekanand
authors.affiliation: Organic Synthesis Group, Department of Chemistry, School of Chemical and Biotechnology, SASTRA University , Thanjavur 613401, Tamil Nadu, India.
authors.forename: Subbiah
authors.initials: S
authors.lastname: Nagarajan
authors.affiliation: Organic Synthesis Group, Department of Chemistry, School of Chemical and Biotechnology, SASTRA University , Thanjavur 613401, Tamil Nadu, India.
authors.forename: C Uma
authors.initials: CU
authors.lastname: Maheswari
authors.affiliation: Departamento de Química Orgánica y Farmacéutica, Facultad de Farmacia, Universidad Complutense , 28040 Madrid, Spain.
authors.forename: J Carlos
authors.initials: JC
authors.lastname: Menéndez
authors.affiliation: Organic Synthesis Group, Department of Chemistry, School of Chemical and Biotechnology, SASTRA University , Thanjavur 613401, Tamil Nadu, India.
authors.forename: Vellaisamy
authors.initials: V
authors.lastname: Sridharan