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

Abstract

Synthesis of complex hybrid heterocycles containing [1,6]-naphthyridine under metal-free green conditions.

Diels–Alder Cycloaddition Reactions in Sustainable Media

“…They observed that the experimental rate constants were dependent on the percentage of urea in the carbohydrate melt; however, the best correlation was found to be with the solvent viscosity, which is in agreement with previous reports by the authors [67]. The Diels-Alder reaction of 9-anthracenemethanol (54) and N-ethylmaleimide (55a) in different solvent media under conventional heating and ultrasonic activation has been reported [68]. The influence of the solvent medium in the yield of the reaction was assessed by comparing DESs, obtained by the combination of different HBAs (e.g., choline chloride, methyltriphenylphosphonium chloride, (±)-menthol) and HBDs (e.g., glycerol (Gly), ethylene glycol (EG), urea), with water and organic solvents.…”

“…The intramolecular Povarov reaction of 2-aminoarylaldehydes bearing a tethered alkyne moiety with heterocyclic amines catalyzed by Amberlyst-15 in PEG-200 has been described [54]. This metal-free green protocol allowed the synthesis of [1,6]naphthyridine-fused heterocycles 33 and 35 in good yields (60-81%) starting from 2-(N-Scheme 5.…”

“…It is noteworthy that these reactions also worked using acetonitrile as solvent media; however, less solvent volume and reduced reaction times were required when using PEG-400. The intramolecular Povarov reaction of 2-aminoarylaldehydes bearing a tethered alkyne moiety with heterocyclic amines catalyzed by Amberlyst-15 in PEG-200 has been described [54]. This metal-free green protocol allowed the synthesis of [1,6] The intramolecular Povarov reaction of 2-aminoarylaldehydes bearing a tethered alkyne moiety with heterocyclic amines catalyzed by Amberlyst-15 in PEG-200 has been described [54].…”

“…The intramolecular Povarov reaction of 2-aminoarylaldehydes bearing a tethered alkyne moiety with heterocyclic amines catalyzed by Amberlyst-15 in PEG-200 has been described [54]. This metal-free green protocol allowed the synthesis of [1,6] The intramolecular Povarov reaction of 2-aminoarylaldehydes bearing a tethered alkyne moiety with heterocyclic amines catalyzed by Amberlyst-15 in PEG-200 has been described [54]. This metal-free green protocol allowed the synthesis of [1,6]-naphthyridinefused heterocycles 33 and 35 in good yields (60-81%) starting from 2-(N-propargylamino)-arylaldehydes 31 and 3-aminocoumarins 32 or 3-methyl-1-aryl-1H-pyrazol-5-amines 34, respectively (Scheme 7).…”

“…In the absence of noncovalent interactions (e.g., with ethyl acrylate), thermodynamic control prevails and regioisomeric mixtures were obtained. A comparative study on the rates of the Diels-Alder reaction of 9hydroxymethylanthracene (54) and N-phenylmaleimide (55c) in water, ethylene glycol and conventional organic solvents (butan-1-ol, acetonitrile, chloroform and 1,4-dioxane) has been reported (Scheme 24) [92]. Kinetic measurements, performed at 45 °C using spectrophotometric methods, showed that, under homogeneous conditions, no relevant Scheme 23.…”