Facile synthesis of functionalized quinolinones in a green reaction medium and their photophysical properties.

A facile and green chemical approach was successfully developed to construct functionalized quinolinones utilizing substituted alcohols, alkyl acetoacetate, and α-bromo ketones. Various quinolinones bearing either electron-rich or electron-deficient groups at different positions were synthesized in moderate to good yields under mild reaction conditions. The plausible mechanistic pathway for this transformation is supported by experimental evidence and control experiments.

One-Pot Sequential Synthesis of Alkenylated Dihydroquinolinones and Hexahydroacridinones in Deep Eutectic Solvent Medium.

The sequential synthesis of -heterocycles from saturated ketones poses significant challenges and has rarely been reported. Herein, an efficient synthesis of alkenylated dihydroquinolinones and hexahydroacridinones is achieved from saturated ketones or via dehydrogenation, cyclization, oxidation, and α-alkenylation in choline chloride-based deep eutectic solvent (DES) medium. This strategy provides alkenylated dihydroquinolinones and hexahydroacridinones in excellent yield from low-cost, readily available starting materials under environmentally benign conditions.

Mn-Catalyzed Ligand-Free One-Pot Synthesis of ()-6,7-Dihydrodibenzo[,][1,7]phenanthrolines and ()-1,2,3,4-Tetrahydrobenzo[][1,6]naphthyridines through Dehydrogenative Friedlander Annulation/C(sp)-H Functionalization.

An efficient, MnO-catalyzed ligand-free synthesis of ()-6,7-dihydrodibenzo[,][1,7]phenanthrolines, and ()-1,2,3,4-tetrahydrobenzo[][1,6]naphthyridines, utilizing, 2-amino-5-chloro-benzhydrol, acridinol, or 1-benzyl-4-piperidinol, , and benzyl alcohols, is reported. The MnO-catalyzed dehydrogenative Friedlander annulation utilizing ChCl/p-TSA (DES-1) and subsequent C(sp)-H functionalization with TBAB/p-TSA (DES-2) was effected at 100 °C. The optimized reaction conditions gave excellent product yields, and the products were evaluated for their by UV absorption and fluorescence emission studies.

Copper-catalyzed dehydrogenative cyclization/alkenylation towards dihydroquinolinones.

An efficient copper-catalyzed one-pot sequential synthesis of alkenylated quinolinyl dihydroquinolinones is reported, utilizing ketones, 1,3-cyclohexanediones, and benzyl alcohols dehydrogenative cyclization, followed by alkenylation. This highly straightforward method provides a mild and environmentally friendly approach, and scalable reactions are carried out without generating side products. Furthermore, a plausible reaction mechanism is proposed based on control-experiment studies and reaction monitoring H NMR analysis.

Cu/TEMPO catalyzed dehydrogenative 1,3-dipolar cycloaddition in the synthesis of spirooxindoles as potential antidiabetic agents.

A series of spiro-[indoline-3,3'-pyrrolizin/pyrrolidin]-2-ones, 4, 5 and 6 were synthesized in a sequential manner from Cu-TEMPO catalyzed dehydrogenation of alkylated ketones, 1 followed by 1,3-dipolar cycloaddition of azomethine ylides decarboxylative condensation of isatin, 2 and l-proline/sarcosine, 3 in high regioselectivities and yields. The detailed mechanistic studies were performed to identify the reaction intermediates, which revealed that the reaction proceeds dehydrogenative cycloaddition. Additionally, the regio and stereochemistry of the synthesized derivatives were affirmed by 2D NMR spectroscopic studies.

Facile Synthesis of 2-Acylthieno[2,3-]quinolines via Cu-TEMPO-Catalyzed Dehydrogenation, sp-C-H Functionalization (Nucleophilic Thiolation by S) of 2-Haloquinolinyl Ketones.

An efficient, solvent-free synthesis of 2-acylthieno[2,3-]quinolines is reported from 2-halo-quinolinyl ketones through Cu-TEMPO catalyzed dehydrogenation, sp-C-H functionalization using elemental sulfur as thiol surrogate (sulfur source) and tetrabutylammonium acetate as an ionic reaction medium. The optimized reaction conditions give excellent product yields under mild reaction conditions with chemoselectivity and broad functional group tolerance. The synthetic importance of the synthesized molecules is showcased further by Friedländer annulation, reduction, and alkene functionalization reactions.

Facile synthesis of N-1,2,4-oxadiazole substituted sulfoximines from N-cyano sulfoximines.

A divergent approach has been successfully developed for the synthesis of N-1,2,4-oxadiazole substituted sulfoximines starting from N-cyano sulfoximines. This method has a wide degree of substrate scope that includes aryl, heteroaryl, alkyl, fluoroalkyl and saturated heterocyclic compounds. Excellent functional group tolerability was also observed.

Choline Chloride-Based Deep Eutectic Systems in Sequential Friedländer Reaction and Palladium-Catalyzed sp CH Functionalization of Methyl Ketones.

A volatile organic solvent-free and choline chloride (ChCl)-based deep eutectic system (DES)-mediated sp-CH functionalization of acetophenones with benzyl alcohols to the corresponding α, β-saturated ketones is accounted for. The domino dehydrogenation-aldol condensation (hydrogenation borrowing concept) has been successfully attempted with palladium-tetrakis(triphenylphosphine) [Pd(PPh)] catalyst-xantphos ligand combination. Furthermore, a sequential Friedländer reaction of 2-aminobenzophenone and palladium-catalyzed α-alkylation of the quinolinyl methyl ketone with benzyl alcohols in ChCl-based DES have been successfully investigated.