Mn(OAc) 3 *2H 2 O promoted addition of arylboronic acids to quinoxalin-2-ones

Paired Electrolysis-Enabled Arylation of Quinoxalin-2(1H)-ones

The first paired electrolysis-enabled arylation of quinoxalin-2(1H)-ones was achieved using cyanoarenes as the arylation reagents. A variety of 3-arylquinoxalin-2(1H)-ones with various important functional groups were obtained in moderate to good yields under metal- and chemical oxidant-free conditions. With a pair of reductive and oxidative processes occurring among the substrates and reaction intermediates, the power consumption can be dramatically reduced.

Visible Light-Induced Metal-free Arylation of Coumarin-3-carboxylates with Arylboronic Acids

The present work represents a novel methodology for the selective arylation of coumarin-3-carboxylates with arylboronic acids via a photochemical route, marking the first-ever attempt for the direct alkenyl C-H arylation using rose bengal as a photocatalyst, which is a readily available and cost-effective alternative to transition metal catalysis. The reaction proceeds smoothly in MeOH/H2O solvent media in the presence of radical initiator affording the arylated products in good yields (60-80 %). The reaction parameters such as visible light, radical initiator, oxidant, anhydrous solvent, and inert atmosphere play a crucial role for the success of this methodology. The substituents present on the substrate show a significant effect on the conversion. This study provides a valuable contribution to the field of organic synthesis offering a new and efficient approach to the arylation of coumarin-3-carboxylic acid esters with a broad substrate scope and high functional group tolerance. It is a versatile method and provides a direct access to biologically relevant 4-arylcoumarin-3-carboxylates.

Oxidative Radical Transnitrilation of Arylboronic Acids with Trityl Isocyanide

We report a radical transnitrilation of arylboronic acids with trityl isocyanide in the presence of manganese(III) acetate. Many functional groups can be tolerated in this transformation, and a special positive effect of benzoic acid in this reaction has been observed.

Electrochemical Oxidative C-H Arylation of Quinoxalin(on)es with Arylhydrazine Hydrochlorides under Mild Conditions

A practical and scalable protocol for electrochemical arylation of quinoxalin(on)es with arylhydrazine hydrochlorides under mild conditions has been developed. This method exhibits high efficiency, easy scalability, and broad functional group tolerance. Various quinoxalin(on)es and arylhydrazines underwent this transformation smoothly in an undivided cell, providing the corresponding aryl-substituted quinoxalin(on)es in moderate to good yields. A radical mechanism is involved in this arylation reaction.

Mn(OAc)3 Induced C-4 Arylations of Quinazoline 3-Oxides with Arylboronic Acids

The use of manganese triacetate as an oxidant component in the C-4 arylations of 2-aryl-quinazoline 3-oxides with arylboronic acids­ is reported. The new protocol was applied to prepare new 2,4-di­arylated quinazoline 3-oxides in good to high yields. The method was shown to tolerate various substituents on both aromatic rings, and no complications such as deoxygenation or rearrangement to quinazolin-4(3H)-one was observed.

The missing MIL-101(Mn): geometrically guided synthesis and topologically correlated valence states

Through a geometrically guided approach, i.e. with the aid of pyridyl modulators, the long-sought MIL-101(Mn) structure is finally achieved, which features emergent topologically correlated mixed-valence states that are apt for enzymatic catalysis.

Sustainable C–H activation approach for palladium-catalyzed, regioselective functionalization of 1-methyl-3-phenyl quinoxaline-2(1H)-ones in water

An environment-friendly approach for regioselective acylation of 1-methyl-3-phenyl quinoxaline-2(1H)-ones was developed using water as a solvent. The protocol exhibits a wide substrate scope and employs commercially available, non-toxic acyl surrogates.

Synthesis of (E)-Quinoxalinone Oximes through a Multicomponent Reaction under Mild Conditions

Herein, a novel method for the gram-scale synthesis of (E)-quinoxalinone oximes through a multicomponent reaction under mild conditions is described. Such a transformation was performed under transition-metal-free conditions, affording (E)-oximes in a moderate-to-good yield through recrystallization. Our methodology demonstrates a successful combination of a Mannich-type reaction and radical coupling, providing a green and practical approach for the synthesis of potentially bioactive quinoxalinone-containing molecules.

Visible-light-induced aerobic C3–H fluoroalkoxylation of quinoxalin-2(1H)-ones with fluoroalkyl alcohols

A novel and efficient method of visible-light-induced C3–H fluoroalkoxylation of quinoxalin-2(1H)-ones with fluoroalkyl alcohols is developed. This approach uses readily available fluoroalkyl alcohols as fluoroalkoxylation reagents and displays a wide substrate scope, providing the fluoroalkoxylated products in moderate to good yields. Compared with the previous method, such a transformation uses oxygen as an oxidant, which avoids the utilization of plenty of PhI(TFA)₂. In addition, this strategy also gives a practical tool for the rapid synthesis of histamine-4 receptor antagonist and new N-containing bidentate ligands. A radical mechanism was suggested according to the results of control experiments.

A visible-light-induced aerobic C3–H fluoroalkoxylation of quinoxalin-2(1H)-ones with fluoroalkyl alcohols was reported, providing a green access to fluoroalkoxylated quinoxalin-2(1H)-ones.

Transition-metal-free direct C-3 cyanation of quinoxalin-2(1H)-ones with ammonium thiocyanate as the “CN” source

A practical protocol for TBHP-mediated oxidative C–H cyanation of quinoxalin-2(1H)-ones utilizing ammonium thiocyanate as the cyanide source has been developed under metal free conditions.

Photoinitiated decarboxylative C3-difluoroarylmethylation of quinoxalin-2(1H)-ones with potassium 2,2-difluoro-2-arylacetates in water

An efficient visible-light-induced decarboxylative C3-difluoroarylmethylation of quinoxalin-2(1H)-one with potassium 2,2-difluoro-2-arylacetate in water at room temperature was developed.

Visible-light-promoted acridine red catalyzed aerobic oxidative decarboxylative acylation of α-oxo-carboxylic acids with quinoxalin-2(1H)-ones

Visible-light-mediated procedure has been developed for the synthesis of 3-acyl quinoxalin-2(1H)-ones through acridine red catalyzed decarboxylative acylation of α-oxo-carboxylic acids with quinoxalin-2(1H)-ones.

Photocatalyst-, metal- and additive-free, direct C–H arylation of quinoxalin-2(1H)-ones with aryl acyl peroxides induced by visible light

A visible light-mediated direct C–H arylation of quinoxalin-2(1H)-ones with aryl acyl peroxides has been developed.

K2S2O8 mediated C-3 arylation of quinoxalin-2(1H)-ones under metal-, photocatalyst- and light-free conditions

Two facile and effective C-3 arylation protocols of quinoxalin-2(1H)-ones with arylhydrazines and aryl boronic acids respectively via free radical cross-coupling reactions under metal-, photocatalyst- and light-free conditions have been unveiled. K₂S₂O₈ has been used as an efficient oxidant to generate aryl radicals from arylhydrazines and aryl boronic acids under two different reaction conditions. The generated aryl radicals undergo a free radical coupling reaction at the C-3 position of quinoxalin-2(1H)-ones producing 3-arylquinoxalin-2(1H)-ones in good to excellent yields. The involvement of radicals in the course of the reaction has been demonstrated by radical trapping experiments with 2,2,6,6-tetramethylpiperidine-1-oxyl.

C-3 arylation protocols of quinoxalin-2(1H)-ones with arylhydrazines and aryl boronic acids under metal-, photocatalyst- and light-free conditions using non-toxic K₂S₂O₈.

Recent advances in the direct functionalization of quinoxalin-2(1H)-ones

The direct C3-functionalization of quinoxalin-2(1H)-ones via C-H bond activation has recently attracted considerable attention, due to their diverse biological activities and chemical properties. This review will focus on the recent achievements, mainly including arylation, alkylation, acylation, alkoxycarbonylation, amination, amidation and phosphonation of quinoxalin-2(1H)-ones. Their mechanisms are also discussed.

The visible-light-triggered regioselective alkylation of quinoxalin-2(1H)-ones via decarboxylation coupling

An efficient protocol to synthesize 3-alkylated quinoxalin-2(1H)-ones through photocatalytic decarboxylation coupling reactions of quinoxalin-2(1H)-ones with N-hydroxyphthalimide ester was developed.

A visible light mediated, metal and oxidant free highly efficient cross dehydrogenative coupling (CDC) reaction between quinoxalin-2(1H)-ones and ethers

The white light mediated, 3C alkylation of quinoxalin-2(1H)-ones via a cross dehydrogenative coupling (CDC) reaction with cyclic ethers using eosin Y as a photocatalyst is described. The reaction proceeds via a hydrogen abstraction and transfer process.

Copper-catalyzed C–H/N–H cross-coupling reactions for the synthesis of 3-heteroaryl quinoxalin-2(1H)-ones

An effective copper-catalyzed C–H/N–H cross-coupling of quinoxalin-2(1H)-ones with diverse unprotected 2-quinoxalinones and 2-quinolinones was developed.

Visible-light induced decarboxylative alkylation of quinoxalin-2(1H)-ones at the C3-position

3-Alkylquinoxalin-2(1H)-ones are synthesized via direct alkylation of quinoxalin-2(1H)-ones at the C3 position under visible light irradiation.