Heterogeneous Amberlyst-15-catalyzed synthesis of complex hybrid heterocycles containing [1,6]-naphthyridine under metal-free green conditions

An efficient green protocol for the synthesis of complex hybrid heterocycles containing [1,6]-naphthyridine and coumarin/pyrazole moieties was established, involving an intramolecular [4 + 2] hetero Diels-Alder reaction as the key step. The biologically significant 12,13-dihydro-6 H -benzo[ h ]chrom...

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Bibliographic Details
Published in:Organic & biomolecular chemistry 2019-07, Vol.17 (28), p.6872-6879
Main Authors: Muthukrishnan, Isravel, Vachan, B. S, Karuppasamy, Muthu, Eniyaval, A, Uma Maheswari, C, Nagarajan, Subbiah, Menéndez, J. Carlos, Sridharan, Vellaisamy
Format: Article
Language:English
Subjects:
Amines
Aromatic compounds
Atom economy
Catalysis
Catalysts
Chemical synthesis
Coumarin
Metals
NMR
Nuclear magnetic resonance
Pyrazole
Transition metals
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Summary:An efficient green protocol for the synthesis of complex hybrid heterocycles containing [1,6]-naphthyridine and coumarin/pyrazole moieties was established, involving an intramolecular [4 + 2] hetero Diels-Alder reaction as the key step. The biologically significant 12,13-dihydro-6 H -benzo[ h ]chromeno[3,4- b ][1,6]naphthyridin-6-ones and 6,10-dihydro-5 H -benzo[ h ]pyrazolo[3,4- b ][1,6]naphthyridines were synthesized starting from 2-( N -propargylamino)-arylaldehydes and 3-aminocoumarins or 3-methyl-1-aryl-1 H -pyrazol-5-amines in the presence of an Amberlyst-15 catalyst in PEG-200 in good yields. The easy access to diverse complex molecules in a single operation from readily available starting materials, a commercially available, transition metal-free and recyclable catalyst, the use of a green solvent, a very high atom economy and the release of water as the only side product are the highlights of this protocol. Synthesis of complex hybrid heterocycles containing [1,6]-naphthyridine under metal-free green conditions.
ISSN:1477-0520
1477-0539
DOI:10.1039/c9ob01256g