Synthesis of 6-(4-methyl-1-piperazinyl)-7H-indeno[2,1-c]-quinoline derivatives as potential 5-HT receptor ligands

Synthesis and Mechanistic Insights of the Formation of 3-Hydroxyquinolin-2-ones including Viridicatin from 2-Chloro-N,3-diaryloxirane-2-carboxamides under Acid-Catalyzed Rearrangements

N-Benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides, easily obtained from aromatic aldehydes and anilides of dichloroacetic acid under Darzens condensation conditions, proved to be excellent starting compounds for the synthesis of 3-hydroxyindolin-2-ones, cyclohepto[b]pyrrole-2,3-diones, and 1-azaspiro[4.5]deca-3,6,9-triene-2-ones via the C(sp²)-C(sp²) bond formation in the first case and C(sp²)-C(sp³) bond formation in the second and third cases. Under optimized reaction conditions, 3-hydroxyindolin-2-ones are obtained in a one-pot process, which involves the treatment of N-benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides with CF₃CO₂H or AcOH/H₂SO₄. In the case of intramolecular cyclization, the detailed reaction channels depend strongly on the substituents present in the anilide component and in the aromatic ring of the aldehyde component of N-benzyl-2-chloro-N,3-diaryloxirane-2-carboxamides, as well as the temperature and duration of the reaction. A combined experimental and DFT mechanistic study of the formation of 1-benzyl-3-hydroxy-4-arylquinolin-2(1H)-ones showed that there are three competing reaction channels: (a) ring-closure via the ipso site, (b) ring-closure via the 1,2-Cl shift, and (c) ring-closure via the ortho site. Such mechanistic insights enabled an effective one-pot gram-scale synthesis of viridicatin from benzaldehyde and 2,2-dichloro-N-(4-methoxybenzyl)-N-phenylacetamide.

Radical Annulation of 2-Cyanoaryl Acrylamides via C═C Double Bond Cleavage: Access to Amino-Substituted 2-Quinolones

A novel annulation of 2-cyanoaryl acrylamides via C═C double bond cleavage has been developed for facile and efficient access to a broad spectrum of functionalized 4-amino-2-quinolones, which are important N-heterocycles. In this transformation, the solvent THF is demonstrated to play a crucial role, and the addition of alkyl radicals to nitrile, 1,5-hydride shift, and cleavage of the C-C bond are involved in the mechanism.

Physicochemical properties of a urea/zinc chloride eutectic mixture and its improved effect on the fast and high yield synthesis of indeno[2,1-c]quinolines

An environmentally friendly and efficient method for the synthesis of indeno[2,1-c]quinolines is developed using a urea/zinc chloride eutectic mixture as a green mildly acidic medium.

A palladium-catalyzed intramolecular carbonylative annulation reaction for the synthesis of 4,5-fused tricyclic 2-quinolones

A new method for the synthesis of 4,5-fused tricyclic 2-quinolones via a palladium-catalyzed intramolecular carbonylative annulation reaction is described.

Synthesis of quinolinones with palladium-catalyzed oxidative annulation between acrylamides and arynes

An unprecedented palladium-catalyzed oxidative annulation of acrylamides with benzyne precursors has been successfully developed. By using this mild "N-H activation/Heck reaction" method, a wide variety of quinolinones were conveniently prepared in one step with high efficiency.

Ruthenium-catalyzed cyclization of anilides with substituted propiolates or acrylates: an efficient route to 2-quinolinones

A Ru-catalyzed cyclization of anilides with propiolates or acrylates affording 2-quinolinones having diverse functional groups in good to excellent yields is described. Later, 2-quinolinones were converted into 3-halo-2-quinolinones and 2-chloroquinolines. The proposed mechanism was strongly supported by experimental evidence and deuterium labeling studies.

A straight forward synthesis of 4-aryl substituted 2-quinolones via Heck reaction

Pd–NHC catalyzed one pot synthesis of 4-aryl-2-quinolones through the Heck reaction followed by cyclization. Additionally an efficient methodology has been developed for Heck reaction with a wide range of arylhalides and olefins.

Synthesis of 2(1H)-quinolinones via Pd-catalyzed oxidative cyclocarbonylation of 2-vinylanilines

Palladium-catalyzed oxidative cyclocarbonylation of N-monosubstituted-2-vinylanilines constitutes a simple, direct, and selective method for the synthesis of 2(1H)-quinolinones. The reaction conditions are attractive in terms of environmental considerations and operational simplicity. 2(1H)-Quinolinones with a variety of functional groups were prepared in up to 97% yield.

An efficient synthesis of 4-arylquinolin-2(1H)-ones and 3-alkenyl-4-arylquinolin-2(1H)-one using a Pd/NiFe2O4-catalyzed consecutive Heck reaction

A convenient one-pot method for the synthesis of 4-arylquinolin-2(1H)-ones and 4-arylcoumarins has been described. The successive Heck reaction on substituted 2-iodoaniline and 2-iodophenol catalyzed by a Pd/nickel ferrite catalyst followed by in situ cyclization was the key step. The scope of this methodology was extended to the synthesis of bioactive 3-alkenyl derivatives of 4-arylquinolin-2(1H)-ones.

Microwave-assisted, palladium-catalyzed carbonylative cyclization — Rapid synthesis of 2-quinolones from unprotected 2-iodoanilines and terminal alkynes

Palladium-catalyzed cyclocarbonylations of 2-iodoanilines with various terminal alkynes have been carried out by the use of commercially available molybdenum hexacarbonyl as a convenient and solid carbon monoxide source. The reactions were conducted at 160 °C for 30 min under microwave irradiation and in the presence of Et3N in THF, affording the corresponding 2-quinolone derivatives in good regioselectivities and yields.

Synthesis of 2-Quinolones via Palladium-Catalyzed Carbonylative Annulation of Internal Alkynes byN-Substitutedo-Iodoanilines

The palladium-catalyzed annulation of internal alkynes by N-substituted o-iodoanilines under 1 atm of carbon monoxide results in the formation of 3,4-disubstituted 2-quinolones. The nature of the substituent on the nitrogen is crucial to obtaining high yields of 2-quinolones. The best results are obtained using alkoxycarbonyl, p-tolylsulfonyl, and trifluoroacetyl substituents. The nitrogen substituent is lost during the course of the reaction resulting in the formation of N-unsubstituted 2-quinolones. A variety of internal alkynes, bearing alkyl, aryl, heteroaryl, hydroxyl, and alkoxyl substituents, are effective in this process. Electron-rich and electron-poor N-substituted o-iodoanilines, as well as heterocyclic analogues, can be employed as annulating agents.