A diversity-oriented synthesis of caroverine derivatives via TEMPO-promoted aerobic oxidative CN bond formation

Visible-Light-Induced Photocatalytic Deoxygenative Benzylation of Quinoxalin-2-(1H)-ones with Carboxylic Acid Anhydrides

A visible-light-induced photocatalytic deoxygenative benzylation of quinoxalin-2-(1H)-ones is herein described. This novel approach provides a mild, simple, and practical route to 3-benzylquinoxalin-2(1H)-ones from ubiquitous and safe carboxylic acid anhydrides. A wide range of substrates with different substituents were well-tolerated and efficiently transformed to various functionalized 3-benzylquinoxalin-2(1H)-ones with great potential for valuable applications in drug discovery. Mechanistic investigations suggest H2O as a proton source, while hydroxyl-containing quinoxalin-2(1H)-ones may be key intermediates of the photocatalytic deoxygenative process.

Visible-Light-Driven Regioselective Decarboxylative Acylation of N-Methyl-3-phenylquinoxalin-2(1H)-one by Dual Palladium-Photoredox Catalysis Through C-H Activation

We report herein an efficient visible-light-promoted approach for the regioselective decarboxylative C-H acylation of N-methyl-3-phenylquinoxalin-2(1H)-ones using α-oxo-2-phenylacetic acids via dual palladium-photoredox catalysis. The reactions were carried out at room temperature in the presence of 24 W blue LEDs. The established protocol tolerated a wide range of functional groups and enabled the synthesis of several acylated N-methyl-3-phenylquinoxalin-2(1H)-ones in good to excellent yields. The proposed mechanism for this transformation was supported by control experiments.

α-Functionalization of ketones promoted by sunlight and heterogeneous catalysis in the aqueous phase

Herein, a protocol that combines heterogeneous catalysis and solar photocatalysis for the regioselective α-substitution of asymmetric ketones with quinoxalinones has been reported. The result indicates that the reaction is more likely to occur on the α-carbon. This strategy provides a green and efficient way for the α-functionalization of ketones. A singlet oxygen involved mechanism is suggested for the transformation.

Alkylsulfonium salts for the photochemical desulphurizative functionalization of heteroarenes

A metal-free organic photoredox-catalyzed alkylation of heteroarenes using alkylsulfonium salts as alkylation reagents has been developed.

Metal-Free Alkylation of Quinoxalinones with Aryl Alkyl ketones

The first metal-free method for alkylation of quinoxalinones using cheap and stable aryl alkyl ketones as nucleophilic alkylation reagents is reported. This strategy greatly broadens the application channels of aryl...

TEMPO-Mediated C-H Amination of Benzoxazoles with N-Heterocycles

The direct amination of benzoxazoles at C2 using N-heterocycles as nitrogen sources has been developed for the first time. Several kinds of inexpensive oxidants and also electricity were effective for this transformation in the presence of 2,2,6,6-tetramethylpiperidine-N-oxyl. This metal-free and operationally simple reaction can afford a variety of important C,N'-linked bis-heteocycles in moderate to good yields under very mild reaction conditions. The in situ generated oxoammonium salt was proved to be important for this transformation.

Construction of C(sp2 )-C(sp3 ) Bond between Quinoxalin-2(1H)-ones and N-Hydroxyphthalimide Esters via Photocatalytic Decarboxylative Coupling

A novel visible-light-driven decarboxylative coupling of alkyl N-hydroxyphthalimide esters (NHP esters) with quinoxalin-2(1H)-ones has been developed. This C(sp² )-C(sp³ ) bond-forming transformation exhibits excellent substrate generality with respect to both the coupling partners. Of note, a series of 3-primary alkyl-substituted quinoxalin-2(1H)-ones that were difficult to synthesize by previous methods could be obtained in moderate to excellent yields. Additionally, the mild conditions, easy availability of substrates, wide functional group tolerance and operational simplicity make this protocol practical in the synthesis of 3-alkylated quinoxalin-2(1H)-ones.

Metal-free oxidative ring contraction of benzodiazepinones: an entry to quinoxalinones

Herein is reported a practical method for the construction of 3-benzoylquinoxalinones from benzodiazepinones in the presence of DMSO which serves both as a solvent and an oxidant.