cas 5021-43-2, 2-Phenylquinoxaline | Articles data

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Quinoxaline synthesis via oxidative cyclization reaction using metal-organic framework Cu(BDC) as an efficient heterogeneous catalyst
A metal-organic framework Cu(BDC) was synthesized, and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. The Cu(BDC) was employed as an efficient heterogeneous catalyst for the oxidative cyclization reaction between α-hydroxyacetophenone and phenylenediamine to form 2-phenylquinoxaline as the principal product. The optimal conditions involved the use of air atmosphere oxidant in toluene solvent at 100°C in 3 h. In addition, the Cu(BDC) exhibited higher catalytic activity in the quinoxaline synthesis reaction than that of others Cu-MOFs such as MOF-199, MOF-118, and Cu2(BDC)2(DABCO), and higher than that of Mn(BDC), and Ni2(BDC)2(DABCO). The Cu(BDC) catalyst could be recovered and reused several times without a significant degradation in catalytic activity.
Dang, Giao H.,Vu, Yen T. H.,Dong, Quoc A.,Le, Dung T.,Truong, Thanh,Phan, Nam T. S.
p. 189 - 195
(2015)
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Deactivation of Cu3(BTC)2 in the synthesis of 2-phenylquinoxaline
Cu3(BTC)2 deactivates by deterioration of its crystal structure during the use of this metal organic framework as catalyst in the synthesis of 2-phenylquinoxaline from phenacylbromide and o-phenylenediamine at room temperature. The m
Dhakshinamoorthy, Amarajothi,Alvaro, Mercedes,Garcia, Hermenegildo
p. 1600 - 1605
(2015)
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Facile synthesis of multipodal MnO nanocrystals and their catalytic performance
Multipodal manganese oxide nanocrystals, synthesized through the thermal decomposition of a Mn-oleate complex, exhibited catalytic activity for the synthesis of a quinoxaline derivative from a α-hydroxy ketone with a 1,2-diamine. The MnO nanocrystals are single crystalline and uniform multipodal, with an average estimated distance of (47 ± 2) nm between the tips of two pods. Multipodal MnO nanocrystals are synthesized through thermal decomposition of a Mn-oleate complex. The MnO nanocrystals are single crystalline and uniform multipodal with an average estimated distance of (47 ± 2) nm between the tips of the two pods. These nanocrystals can efficiently catalyze the synthesis of a quinoxaline derivative from an α-hydroxy ketone with a 1,2-diamine.
Kim, Aram,Shin, Dongwoo,Kim, Mijong,Yoon, Chohye,Song, Hyunjoon,Park, Kang Hyun
p. 1279 - 1283
(2014)
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Tetrabutylammonium Bromide-Catalyzed Transfer Hydrogenation of Quinoxaline with HBpin as a Hydrogen Source
A metal-free environmentally benign, simple, and efficient transfer hydrogenation process of quinoxaline has been developed using the HBpin reagent as a hydrogen source. This reaction is compatible with a variety of quinoxalines offering the desired tetrahydroquinoxalines in moderate-to-excellent yields with Bu4NBr as a noncorrosive and low-cost catalyst.
Guo, Qi,Chen, Jingchao,Shen, Guoli,Lu, Guangfu,Yang, Xuemei,Tang, Yan,Zhu, Yuanbin,Wu, Shiyuan,Fan, Baomin
p. 540 - 546
(2021/12/27)

Direct C-2 arylation of quinoxaline with arylhydrazine salts as arylation reagents
A transition metal-free synthesis of 2-arylquinoxaline is achieved by using arylhydrazine salt as an aryl radical arylation reagent and air as an oxidant in the presence of K2CO3. This protocol features metal-free, no additives, mild reaction conditions, environment friendly, and can be used to construct biologically active molecules containing 2-phenylquinoxaline structure.
Chen, Yi,Miao, Jing,Tang, Lei,Wang, Bing,Wang, Cong,Wang, Haibo,Wang, Jianta,Wang, Xing,Zhang, Jiquan,Zhu, Gaofeng
supporting information

(2022/03/15)

Mechanochemical Synthesis of 2-Arylquinoxalines and 3-Arylquinoxalin-2(1H)-ones via Aryldiazonium Salts
A green synthesis strategy of 2-arylquinoxalines and 3-arylquinoxalin-2(1H)-ones via ball milling, which could avoid copious solvent waste, was accomplished in this work. Aryl radicals were produced from aryldiazonium salts by using a solvent-free or catalyst-free single electron transfer process induced by mechanical force, affording a series of 2-arylquinoxalines and 3-arylquinoxalin-2(1H)-ones with 28%–85 yield. (Figure presented.).
Liu, Fu,Chen, Li-Ning,Chen, Ai-Min,Ye, Zhi-Peng,Wang, Zhi-Wei,Liu, Zhi-Lin,He, Xian-Chen,Li, Shu-Hui,Xia, Peng-Ju
supporting information
p. 1080 - 1084
(2022/02/21)

Cobalt-catalyzed cross-coupling of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium reagents
Cobalt-catalyzed cross-couplings of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium halides proceeded efficiently with the aid of cobalt(II) catalyst and copper(I) salt in tetrahydrofuran at ambient temperature, producing the desired
Cui, Yan-Ying,Na, Jin-He,Guo, Meng-Meng,Huang, Jie-Ying,Chu, Xue-Qiang,Rao, Weidong,Shen, Zhi-Liang
supporting information

(2022/02/16)

Electrochemical Oxidative Functionalization of Arylalkynes: Access to α,α-Dibromo Aryl Ketones
A general and effective protocol to synthesize α,α-dibromo aryl ketones has been developed via an electrochemical oxidative method. The reaction proceeds smoothly at room temperature in an undivided cell without the addition of external oxidants. In the reaction process, LiBr acts as both bromine source and supporting electrolyte. This electrooxidation strategy has good substrate applicability and functional group compatibility. Moreover, the reaction could be scaled up efficiently in a continuous flow cell. The target product could undergo further functionalization for the synthesis of some useful heterocyclic compounds. (Figure presented.).
Wang, Dan,Wan, Zhaohua,Zhang, Heng,Lei, Aiwen
supporting information
p. 1022 - 1027
(2020/12/31)

2-Phosphinoimidazole Ligands: N-H NHC or P-N Coordination Complexes in Palladium-Catalyzed Suzuki-Miyaura Reactions of Aryl Chlorides
We report the synthesis of two palladium 2-(dialkylphosphino)imidazole complexes and demonstrate their activity as catalysts for Suzuki-Miyaura reactions with (hetero)aryl chlorides at room temperature. Our mechanistic studies demonstrate that these palladium complexes exist as an equilibrium mixture between the P-N coordinated and N-H NHC forms of ligand. Our studies suggest that the N-H NHC form may be important for high catalytic activity in Suzuki-Miyaura reactions with aryl chlorides. These reactions proceed at or near room temperature in good to excellent yields. Heteroaryl chlorides are also reactive at lower catalyst loadings.
Martinez, Erin E.,Larson, Alexandra J. S.,Fuller, Sydney K.,Petersen, Kathryn M.,Smith, Stacey J.,Michaelis, David J.
supporting information
p. 1560 - 1564
(2021/05/29)

Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
We report the tetramethyl ammonium hydroxide catalyzed oxidative coupling of amines and alcohols for the synthesis of imines under metal-free conditions by utilizing oxygen from air as the terminal oxidant. Under the same conditions, with ortho-phenylene diamines and 2-aminobenzenethiols the corresponding benzimidazoles and benzothiazoles were obtained. Quinoxalines were obtained from ortho-phenylene diamines and 1-phenylethane-1,2-diol, the conditions were then extended to the synthesis of quinoline building blocks by reaction of 2-amino benzyl alcohols either with 1-phenylethan-1-ol or acetophenone derivatives. The formation of C?N, C?S and C?C bonds was achieved under metal-free conditions. A broad range of amines (aromatic, aliphatic, cyclic and heteroaromatic) as well as benzylic alcohols including heteroaryl alcohols reacted smoothly and provided the desired products. The mild reaction conditions, commercially available catalyst, metal-free, good functional-group tolerance, broad range of products (imines, benzimidazoles, benzothiazoles, quinoxalines and quinolines) and applicability at gram scale reactions are the advantages of the present strategy.
Adimurthy, Subbarayappa,Badhani, Gaurav,Joshi, Abhisek
p. 6705 - 6716
(2021/12/31)

Silica supported dodecatungstophosphoric acid (DTP/SiO2): An efficient and recyclable heterogeneous catalyst for rapid synthesis of quinoxalines
A facile synthesis of quinoxalines by the cyclocondensation of substituted phenacyl bromides with o-pheneylenediamines using silica-supported dodecatungstophosphoric acid (DTP/SiO2) as a recyclable heterogeneous catalyst is unveiled in this res
Hebade, Madhav J.,Deshmukh, Tejshri R.,Dhumal, Sambhaji T.
p. 2510 - 2520
(2021/06/17)

An efficient and green procedure for the synthesis of quinoxaline derivatives using 3,5-bis(Trifluoromethyl)phenylammonium triflate (bfpat) organocatalyst
The application of 3,5-bis(trifluoromethyl)phenylammonium triflate (BFPAT) as a conven-ient new organocatalyst for the synthesis of quinoxaline derivatives is described. In the presence of BFPAT, one-pot synthesis of a wide variety of quinoxaline derivati
Alipour, Mandana,Hossaini, Zinatossadat,Khaksar, Samad,Rostami-Charati, Faramarz
p. 183 - 186
(2021/03/19)

Synthesis, biological evaluation, and in silico studies of new acetylcholinesterase inhibitors based on quinoxaline scaffold
A quinoxaline scaffold exhibits various bioactivities in pharmacotherapeutic interests. In this research, twelve quinoxaline derivatives were synthesized and evaluated as new acetyl-cholinesterase inhibitors. We found all compounds showed potent inhibitory activity against acetyl-cholinesterase (AChE) with IC50 values of 0.077 to 50.080 μM, along with promising predicted drug-likeness and blood–brain barrier (BBB) permeation. In addition, potent butyrylcholinesterase (BChE) inhibitory activity with IC50 values of 14.91 to 60.95 μM was observed in some compounds. Enzyme kinetic study revealed the most potent compound (6c) as a mixed-type AChE inhibitor. No cytotoxicity from the quinoxaline derivatives was noticed in the human neuroblastoma cell line (SHSY5Y). In silico study suggested the compounds preferred the peripheral anionic site (PAS) to the catalytic anionic site (CAS), which was different from AChE inhibitors (tacrine and galanthamine). We had proposed the molecular design guided for quinoxaline derivatives targeting the PAS site. Therefore, the quinoxaline derivatives could offer the lead for the newly developed candidate as potential acetylcholinesterase inhibitors.
Khongkow, Pasarat,Lomlim, Luelak,Nualnoi, Teerapat,Saetang, Jirakrit,Suwanhom, Paptawan,Tipmanee, Varomyalin
(2021/08/20)

Ruthenium-catalysedmeta-selective CAr-H bond alkylationviaa deaminative strategy
The use of aliphatic amines as alkylating reagents in organic synthesisviaC-N bond activation remains underdeveloped. We herein describe a novel ruthenium-catalysed and directing-group assisted protocol for the synthesis ofmeta-alkylated arenesviadual C-H and C-N activation. Bench-stable and easily handled redox-active Katritzky pyridinium salts derived from abundant amines and amino acid species were used as alkyl radical precursors. This catalytic reaction could accommodate a broad range of functional groups and provide access to variousmeta-alkylated products.
Zhu, Ze-Fan,Chen, Guang-Le,Liu, Feng
supporting information
p. 3411 - 3414
(2021/04/07)

Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
A straightforward and selective reduction of nitroarenes with various alcohols was efficiently developed using an iron catalyst via a hydrogen transfer methodology. This protocol led specifically to imines in 30-91% yields, with a good functional group tolerance. Noticeably, starting from o-nitroaniline derivatives, in the presence of alcohols, benzimidazoles can be obtained in 64-72% yields when the reaction was performed with an additional oxidant, DDQ, and quinoxalines were prepared from 1,2-diols in 28-96% yields. This methodology, unprecedented at iron for imines, also provides a sustainable alternative for the preparation of quinoxalines and benzimidazoles.
Wu, Jiajun,Darcel, Christophe
supporting information
p. 1023 - 1036
(2021/01/09)

NaOH-Mediated Direct Synthesis of Quinoxalines from o-Nitroanilines and Alcohols via a Hydrogen-Transfer Strategy
A NaOH-mediated sustainable synthesis of functionalized quinoxalines is disclosed via redox condensation of o-nitroamines with diols and α-hydroxy ketones. Under optimized conditions, various o-nitroamines and alcohols are well tolerated to generate the desired products in 44-99% yields without transition metals and external redox additives.
Wang, Yan-Bing,Shi, Linlin,Zhang, Xiaojie,Fu, Lian-Rong,Hu, Weinan,Zhang, Wenjing,Zhu, Xinju,Hao, Xin-Qi,Song, Mao-Ping
p. 947 - 958
(2021/01/14)

A heterogeneous catalytic strategy for facile production of benzimidazoles and quinoxalines from primary amines using the Al-MCM-41 catalyst
This study reports a straightforward heterogeneous catalytic (Al-MCM-41) approach to synthesize nitrogen heterocycle moieties from primary amines under solvent-free conditions. The Al-MCM-41 catalyst was prepared using a hydrothermal method and characterized by various analytical techniques. The probability and limitations of the catalytic methodology were presented with various substrates. The catalytic method grants an attractive route to a wide variety of benzimidazole and quinoxaline moieties with good to excellent yields. The gram scale reaction and reusability (up to five cycles) of the Al-MCM-41 catalyst would greatly benefit industrial applications. This journal is
Vasu, Amrutham,Naresh, Mameda,Krishna Sai, Gajula,Divya Rohini, Yennamaneni,Murali, Boosa,Ramulamma, Madasu,Ramunaidu, Addipilli,Narender, Nama
p. 9439 - 9446
(2021/12/09)

Visible light promoted tandem dehydrogenation-deaminative cyclocondensation under aerobic conditions for the synthesis of 2-aryl benzimidazoles/quinoxalines fromortho-phenylenediamines and arylmethyl/ethyl amines
Visible light promoted domino synthesis of 2-aryl benzimidazoles is reported through the reaction ofortho-phenylenediamines and arylmethyl amines under aerobic conditions. The methodology has wide substrate scope and tolerates a wide range of functional groups affording the products in high yields. The use of arylethyl amines instead of arylmethyl amines gives 2-aryl quinoxalines.
Sofi, Firdoos Ahmad,Sharma, Rohit,Rawat, Ravi,Chakraborti, Asit K.,Bharatam, Prasad V.
supporting information
p. 4569 - 4573
(2021/03/22)

Iron-catalyzed one-pot synthesis of quinoxalines: Transfer hydrogenative condensation of 2-nitroanilines with vicinal diols
Here, we report iron-catalyzed one-pot synthesis of quinoxalines via transfer hydrogenative condensation of 2-nitroanilines with vicinal diols. The tricarbonyl (η4-cyclopentadienone) iron complex, which is well known as the Kn?lker complex, catalyzed the oxidation of alcohols and the reduction of nitroarenes, and the corresponding carbonyl and 1,2-diaminobenzene intermediates were generated in situ. Trimethylamine N-oxide was used to activate the iron complex. Various unsymmetrical and symmetrical vicinal diols were applied for transfer hydrogenation, resulting in quinoxaline derivatives in 49-98% yields. A plausible mechanism was proposed based on a series of control experiments. The major advantages of this protocol are that no external redox reagents or additional base is needed and that water is liberated as the sole byproduct. This journal is
Chun, Simin,Hong, Junhwa,Hong, Suckchang,Lee, Seok Beom,Oh, Dong-Chan,Putta, Ramachandra Reddy
p. 18225 - 18230
(2021/06/03)

Hydrogen Auto-transfer Synthesis of Quinoxalines from o-Nitroanilines and Biomass-based Diols Catalyzed by MOF-derived N,P Co-doped Cobalt Catalysts
A Co-based heterogeneous catalyst supported on N,P co-doped porous carbon (Co@NCP) is prepared via a facile in-situ doping-carbonization method. The Co@NCP composite features a large surface area, high pore volume, high-density and strong basic sites. Furthermore, doping of P atoms can regulate the electronic density of Co. Therefore, Co@NCP exhibits good performance for the synthesis of quinoxalines from o-nitroanilines and biomass-derived diols under alkali-free conditions.
Sun, Kangkang,Li, Dandan,Lu, Guo-Ping,Cai, Chun
p. 373 - 381
(2020/12/09)

Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles
Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.
Manna, Srimanta,Kong, Wei-Jun,B?ckvall, Jan-E.
supporting information
p. 13725 - 13729
(2021/09/08)

Application of a reusable Co-based nanocatalyst in alcohol dehydrogenative coupling strategy: Synthesis of quinoxaline and imine scaffolds
A nitrogen doped carbon supported cobalt catalyzed efficient synthesis of imines and quinoxaline motifs is reported. Co(OAc)2-Phen/Carbon-800 (Co-phen/C-800) showed the superior reactivity compared to other materials prepared at different temperature, in the synthesis of quinoxalines by the coupling between diamines and diols. Moreover, applying the transfer hydrogenation and acceptorless dehydrogenative coupling strategy, imines and quinoxaline derivatives were synthesized from the nitro compounds. The practical applicability of this protocol was demonstrated by the gram-scale synthesis and the reusability of the catalyst upto 8th cycle. Furthermore, several kinetic experiments were carried out to realize the probable mechanism.
Panja, Dibyajyoti,Paul, Bhaskar,Balasubramaniam, Bhuvaneshwari,Gupta, Raju K.,Kundu, Sabuj
(2020/01/21)

Nickel-Catalyzed Direct Synthesis of Quinoxalines from 2-Nitroanilines and Vicinal Diols: Identifying Nature of the Active Catalyst
The inexpensive and simple NiBr2/1,10-phenanthroline system-catalyzed synthesis of a series of quinoxalines from both 2-nitroanilines and 1,2-diamines is demonstrated. The reusability test for this system was performed up to the seventh cycle, which afforded good yields of the desired product without losing its reactivity significantly. Notably, during the catalytic reaction, the formation of the heterogeneous Ni-particle was observed, which was characterized by PXRD, XPS, and TEM techniques.
Shee, Sujan,Panja, Dibyajyoti,Kundu, Sabuj
p. 2775 - 2784
(2020/03/13)

Manganese(I)-Catalyzed Sustainable Synthesis of Quinoxaline and Quinazoline Derivatives with the Liberation of Dihydrogen
Direct synthesis of N-heterocycles via the acceptorless dehydrogenative coupling is very challenging and scarcely reported under 3d transition-metal catalysis. Here, we have developed an efficient Mn(I)-catalyzed sustainable synthesis of various quinoxalines from 1,2-diaminobenzenes and 1,2-diols via the acceptorless dehydrogenative coupling reaction. Further, this strategy was successfully applied for the unprecedented synthesis of quinazolines by the reaction of 2-aminobenzyl alcohol with primary amides. The present protocol provides an atom-economical and sustainable route for the synthesis of various quinoxaline and quinazoline derivatives by employing an earth-abundant manganese salt and simple phosphine-free NNN-tridentate ligand.
Mondal, Akash,Sahoo, Manoj Kumar,Subaramanian, Murugan,Balaraman, Ekambaram
supporting information
p. 7181 - 7191
(2020/07/21)

Homogeneous Nickel-Catalyzed Sustainable Synthesis of Quinoline and Quinoxaline under Aerobic Conditions
Dehydrogenative coupling-based reactions have emerged as an efficient route toward the synthesis of a plethora of heterocyclic rings. Herein, we report an efficacious, nickel-catalyzed synthesis of two important heterocycles such as quinoline and quinoxaline. The catalyst is molecularly defined, is phosphine-free, and can operate at a mild reaction temperature of 80 °C. Both the heterocycles can be easily assembled via double dehydrogenative coupling, starting from 2-aminobenzyl alcohol/1-phenylethanol and diamine/diol, respectively, in a shorter span of reaction time. This environmentally benign synthetic protocol employing an inexpensive catalyst can rival many other transition-metal systems that have been developed for the fabrication of two putative heterocycles. Mechanistically, the dehydrogenation of secondary alcohol follows clean pseudo-first-order kinetics and exhibits a sizable kinetic isotope effect. Intriguingly, this catalyst provides an example of storing the trapped hydrogen in the ligand backbone, avoiding metal-hydride formation. Easy regeneration of the oxidized form of the catalyst under aerobic/O2 oxidation makes this protocol eco-friendly and easy to handle.
Bains, Amreen K.,Singh, Vikramjeet,Adhikari, Debashis
p. 14971 - 14979
(2020/11/30)

Organocatalytic combinatorial synthesis of quinazoline, quinoxaline and bis(indolyl)methanes
Aims and Objective: An efficient and practical procedure for the synthesis of heterocyclic compounds such as quinazolines, quinoxalines and bis(indolyl)methanes was developed using 3,5-bis(trifluoromethyl) phenyl ammonium hexafluorophosphate (BFPHP) as a novel organocatalyst. Materials and Methods: All of the obtained products are known compounds and identified by IR, 1HNMR, 13CNMR and melting points. Result: Various products were obtained in good to excellent yields under reaction conditions Conclusion: The BFPHP organocatalyst demonstrates a novel class of non-asymmetric organocatalysts, which has gained much attention in green chemistry.
Badri, Rashid,Khaksar, Samad,Malamiri, Fatemeh,Tahanpesar, Elham
p. 83 - 88
(2020/03/30)

Nature of the Nucleophilic Oxygenation Reagent Is Key to Acid-Free Gold-Catalyzed Conversion of Terminal and Internal Alkynes to 1,2-Dicarbonyls
2,3-Dichloropyridine N-oxide, a novel oxygen transfer reagent, allows the conductance of the gold(I)-catalyzed oxidation of alkynes to 1,2-dicarbonyls in the absence of any acid additives and under mild conditions to furnish the target species, including those derivatized by highly acid-sensitive groups. The developed strategy is effective for a wide range of alkyne substrates such as terminal- and internal alkynes, ynamides, alkynyl ethers/thioethers, and even unsubstituted acetylene (40 examples; yields up to 99%). The oxidation was successfully integrated into the trapping of reactive dicarbonyls by one-pot heterocyclization and into the synthesis of six-membered azaheterocycles. This synthetic acid-free route was also successfully applied for the total synthesis of a natural 1,2-diketone.
Dubovtsev, Alexey Yu.,Shcherbakov, Nikolay V.,Dar'in, Dmitry V.,Kukushkin, Vadim Yu.
p. 745 - 757
(2020/02/04)

Bonded- A nd discreted-Lindqvist hexatungstate-based copper hybrids as heterogeneous catalysts for the one-pot synthesis of 2-phenylquinoxalines: Via 2-haloanilines with vinyl azides or 3-phenyl-2 H-azirines
One bonded- A nd one discreted-Lindqvist hexatungstate-based copper hybrids (Cu-POMs) ([Cu2(O)OH (phen)2]2[W6O19]?6H2O (1) and [Cu2(phen)4Cl] [HW6O19]?2H2O (2) (phen = 1,10-phenanthroline)) were controllably synthesized and routinely characterized. Cu-POM
Gong, Shuwen,Huang, Xianqiang,Lv, Xin,Shen, Guodong,Sun, Manman,Tang, Zhenfei,Wang, Zeyou,Zhang, Jiangong
p. 13993 - 13998
(2020/11/02)

NaH-mediated direct C-H arylation in the presence of 1,10-phenanthroline
Transition-metal-free coupling of haloarenes with unactivated arenes has been developed in the presence of NaH and 1,10-phenanthroline. Various haloarenes bearing methyl, methoxy, halogen (fluoride, chloride, and bromide), cyano, trifluoromethyl, ester, and amide groups can be cross-coupled with unactivated arenes, or heteroarenes in this reaction.
Nozawa-Kumada, Kanako,Iwakawa, Yuki,Onuma, So,Shigeno, Masanori,Kondo, Yoshinori
supporting information
p. 7773 - 7776
(2020/07/27)

Iridium-Catalyzed [4+2] Annulations of β-Keto Sulfoxonium Ylides and o-Phenylenediamines: Mild and Facile Synthesis of Quinoxaline Derivatives
A synthetic method for quinoxaline derivatives from the [4+2] annulation of β-keto sulfoxonium ylides and o-phenylenediamine by using (Cp*IrCl2)2 catalyst is described. This novel protocol features mild reaction conditions, moderate to excellent yields, wide substrate scope, and high functional-group compatibility. Moreover, this cyclization strategy was successfully applied in late-stage modification for structurally complex bioactive compounds.
Che, Tong,Kang, Hua-Jie,Peng, Dongming,Shu, Bing,Song, Jia-Lin,Wang, Xiao-Tong,Xie, Hui,Zhang, Luyong,Zhang, Shang-Shi,Zhong, Mei
(2020/06/25)

Novel green synthesis method for efficiently synthesizing quinoxaline derivative through transition metal catalyzed carbene insertion/cyclization reaction
The invention discloses a novel green synthesis method for efficiently synthesizing a C-N bond and a quinoxaline derivative through a transition metal catalyzed carbene insertion/cyclization reactionby taking pure water as a solvent and sulfur ylide as a carbene donor. Compared with the traditional method, the method has the advantages that the raw materials are easy to obtain, the steps are simple, the use of toxic organic solvents is avoided and the method is a mild, quick, simple, convenient, effective and environment-friendly method for preparing the quinoxaline mother ring and has a wideapplication prospect.
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(2020/05/09)

Iridium-Catalyzed Carbenoid Insertion of Sulfoxonium Ylides for Synthesis of Quinoxalines and β-Keto Thioethers in Water
Sulfoxonium ylides as safe carbene precursors are described for iridium-catalyzed carbene insertions and annulation, providing a facile and green approach to access a variety of quinoxaline derivatives in water. This water-mediated method also allows the preparation of β-keto thioethers under mild condition.
Xu, Yingying,Huang, Xin,Lv, Guanghui,Lai, Ruizhi,Lv, Songyang,Li, Jianglian,Hai, Li,Wu, Yong
supporting information
p. 4635 - 4638
(2020/07/04)

Benzimidazoles and benzothiazoles from styrenes and N-vinylimidazole via palladium catalysed oxidative C[dbnd]C and C[sbnd]N bond cleavage
Herein we report a first, palladium catalyzed, one-pot methodology for the synthesis of pharmacologically important benzimidazoles and benzothiazoles from readily available terminal aromatic olefins. The process involves sequential C[dbnd]C/C[sbnd]N bond cleavage followed by C[sbnd]N/C[sbnd]S bond formation.
Shaikh, Altab,Ravi, Owk,Pushpa Ragini,Sadhana, Nimma,Reddy Bathula, Surendar
(2019/12/26)

Porous carbons-derived from vegetal biomass in the synthesis of quinoxalines. Mechanistic insights
We report herein for the first-time acid biomass-derived carbons from vegetal biomass, with high developed porosity, prepared through integrating method comprising pyrolysis and surface phosphonation, able to efficiently catalyze the synthesis of quinoxalines from 1,2-diamines and α-hydroxi ketones, under aerobic conditions. The obtained results indicate that the reaction is mainly driven by a combination of acid function strength and textural properties in terms of conversion and selectivity. Furthermore, our experimental and theoretical observations suggest that the preferred reaction pathway for this transformation, in the presence of the investigated acid carbon catalysts, involves cascade reactions including imination reaction between reactants, successive imine-enamine and keto-enol tautomerisms, heterocyclization followed by dehydration, and aromatization. While the acid sites seem to be a relevant role in each reaction step, the system formed by activated carbon and molecular oxygen could be behind the last oxidative reaction to give the corresponding nitrogen heterocycles.
Godino-Ojer,Blazquez-García,Matos,Bernardo,Fonseca,Pérez Mayoral
p. 90 - 99
(2019/06/24)

Hydrogenation or Dehydrogenation of N-Containing Heterocycles Catalyzed by a Single Manganese Complex
A highly chemoselective base-metal catalyzed hydrogenation and acceptorless dehydrogenation of N-heterocycles is presented. A well-defined Mn complex operates at low catalyst loading (as low as 2 mol %) and under mild reaction conditions. The described catalytic system tolerates various functional groups, and the corresponding reduced heterocycles can be obtained in high yields. Experimental studies indicate a metal-ligand cooperative catalysis mechanism.
Borghs, Jannik C.,Rueping, Magnus,Zubar, Viktoriia
supporting information

(2020/05/19)

Cobalt-Catalyzed Sustainable Synthesis of Benzimidazoles by Redox-Economical Coupling of o-Nitroanilines and Alcohols
This study reveals cobalt-catalyzed sustainable synthesis of benzimidazoles by redox-economical coupling of o-nitroanilines and alcohols. The major advantage of this report is the use of a commercially available cheap cobalt catalyst to produce a wide variety of 2-substituted benzimidazoles by hydrogen autotransfer without using any additional external redox reagent and costly ligand system. A thorough mechanistic insight of the reaction is proposed by performing a series of control experiments.
Das, Sanju,Mallick, Samrat,De Sarkar, Suman
p. 12111 - 12119
(2019/10/02)

Visible-Light-Enhanced Suzuki–Miyaura Reactions of Aryl Chlorides in Water with Pd NPs Supported on a Conjugated Nanoporous Polycarbazole
The visible-light-enhanced catalytic activation of aryl chlorides for Suzuki–Miyaura cross-coupling (SMC) reactions is highly challenging because of the strength of the C?Cl bond. In this work, palladium nanoparticles (Pd NPs) were grown on a conjugated nanoporous polycarbazole (CNP), named Pd/CNP. The hybrid material Pd/CNP could catalyze the SMC reactions of aryl chlorides with arylboronic acids in water under blue LED irradiation at room temperature with high efficiency. This protocol exhibited good functional group tolerance and the catalyst could be recycled without significant loss of its catalytic activity. CNP not only provided photogenerated electrons to enrich the electron density of the Pd NPs but also generated holes for the activation of the arylboronic acids.
Guo, Bin,Li, Hong-Xi,Zha, Cheng-Hao,Young, David James,Li, Hai-Yan,Lang, Jian-Ping
p. 1421 - 1427
(2019/02/26)

Rhenium-Catalyzed Dehydrogenative Coupling of Alcohols and Amines to Afford Nitrogen-Containing Aromatics and More
An efficient synthesis of quinolines, pyrimidines, quinoxalines, pyrroles, and aminomethylated aromatic compounds catalyzed by a well-defined Re(I) PNP pincer complex is described. All reactions proceed with liberation of dihydrogen and elimination of water. Under optimized reaction conditions a wide range of organic functional groups are tolerated. This study demonstrates that rhenium catalysts are performing extremely well in dehydrogenative processes with considerably lower catalyst loadings and shorter reaction times when compared to analogous Mn(I) complexes.
Mastalir, Matthias,Glatz, Mathias,Pittenauer, Ernst,Allmaier, Günter,Kirchner, Karl
supporting information
p. 1116 - 1120
(2019/05/16)

Cooperative iridium complex-catalyzed synthesis of quinoxalines, benzimidazoles and quinazolines in water
Herein, an efficient methodology for the synthesis of a diverse class of N-heterocyclic moieties, such as quinoxalines, benzimidazoles and quinazolines, was developed in water using bio-renewable alcohols. The quinoxalines were successfully synthesized from a wide range of diamines and nitroamines with diols in air. Interestingly, benzimidazoles and quinazolines were synthesized with excellent isolated yields without using any external base. Finally, the preparative scale synthesis of various N-heterocycles and pharmaceutically active quinoxalines established the practicability of this protocol. For this iridium system, a metal-ligand cooperative mechanism was proposed based on kinetic and DFT studies.
Chakrabarti, Kaushik,Maji, Milan,Kundu, Sabuj
supporting information
p. 1999 - 2004
(2019/04/27)

An environmentally benign attribute for the expeditious synthesis of quinoxaline and its derivatives
A simple, efficient, and environmentally friendly ionic liquid mediated protocol for the synthesis of quinoxaline derivatives using carbonyl substrate and phenylenediamines has been described. A range of ionic liquids were synthesized, characterized via IR, 1H and 13C NMR and used as a solvent as well as catalyst for above protocol. The catalytic activities of ILs were evaluated and the relationship between the catalytic activity and acidity was discussed. It was also found that among the all ILs, [Bmim]CF3SO3 was the most effective, eco-friendly and less expensive solvent and catalyst for the above etiquette. This method is of significant value due to the eco-friendly nature of ionic liquid and non usage of separate catalyst to drive the reaction forward. The protocol proves to be efficient and environmentally benign in terms of good to excellent yields, low reaction times, simple work-up, ease of recovery, and reusability of ionic liquid for six times.
Bhargava, Sangeeta,Soni,Rathore, Deepti
(2019/08/08)

Organocatalytic Green Approach Towards the Fabrication of Fused Benzo N,N-containing Heterocycles Facilitated by Ultrasonic Irradiation
The development of a metal-free protocol for transformations in organic synthesis offers a significant potential environmental benefit. This article reports the exploration of meglumine, a nontoxic and biodegradable amino sugar, as an organocatalyst for the synthesis of biologically active 1H-dibenzo[b,e][1,4]diazepin-1-ones, highly regioselective benzimidazole derivatives and derivatives of quinoxalines. Operational simplicity, mild reaction conditions, shorter reaction times, and use of green solvents are the highlights of this protocol. The advantage of ultrasonic irradiation has been significantly explored for the synthesis of the aforesaid compounds. Furthermore, the multifaceted use of o-phenylenediamine has also been accentuated in the study.
Nongrum, Ridaphun,Kharmawlong, George Kupar,Rani, Jims World Star,Rahman, Noimur,Dutta, Arup,Nongkhlaw, Rishanlang
p. 2873.
(2019/08/26)

Electrochemical Cross-Coupling of C(sp2)?H with Aryldiazonium Salts via a Paired Electrolysis: an Alternative to Visible Light Photoredox-Based Approach
Photoredox-based C?H bond functionalization constitutes one of the most powerful and atom-economical approaches to organic syntheses. During this type of reaction, single electron transfer takes place between the photocatalyst (PC) and redox- active substrates. Electrosynthesis also involves electron transfer between substrates and electrodes. In this paper, we focus upon electrochemical cross-coupling of C(sp2)?H with aryldiazonium salts and have developed an efficient electrochemical approach to the Minisci-type arylation reaction. The constant current paired electrosynthesis proceeds in a simple undivided cell without external supporting electrolyte, features a wide range of substrates and is easy to scale-up. These results demonstrate that photoredox-based cross-coupling of C(sp2)?H with aryldiazonium salts can also proceed successfully under paired electrolysis conditions, thereby contributing to understanding of the parallels between photosynthesis and electrosynthesis. (Figure presented.).
Jiang, Yang-ye,Dou, Gui-yuan,Zhang, Luo-sha,Xu, Kun,Little, R. Daniel,Zeng, Cheng-chu
p. 5170 - 5175
(2019/11/13)

Copper-catalyzed three-component reaction of: N-heteroaryl aldehydes, nitriles, and water
An efficient and straightforward method for the synthesis of N-heteroaroyl imides has been successfully developed involving a copper-catalyzed radical-triggered three-component reaction of N-heteroaryl aldehydes, nitriles, and water. Mechanistic studies indicate that the reaction may undergo a radical-triggered Ritter-type reaction in which water serves as the oxygen source for the formation of the C-O bond. The reaction has advantages such as a broad substrate scope for the N-heteroaryl aldehydes, atom economy, and simple operation.
Bao, Hanyang,Zhou, Bingwei,Jin, Hongwei,Liu, Yunkui
p. 5021 - 5028
(2019/06/03)

Selective synthesis of (1: H-benzo [d] imidazol-2-yl)(phenyl)methanone and quinoxaline from aromatic aldehyde and o-phenylenediamine
We have designed a general, inexpensive, and versatile method for the synthesis of (1H-benzo[d]imidazol-2-yl)(phenyl)methanone and the formation of C-N bonds via an aromatic aldehyde and o-phenylenediamine. In the presence of N,N-dimethylformamide/sulfur, (1H-benzo[d]imidazol-2-yl)(phenyl)methanone was obtained; however, in the absence of sulfur, quinoxaline was obtained in 1,4-dioxane. A wide range of quinoxalines and (1H-benzo[d]imidazol-2-yl)(phenyl)methanones was obtained under mild conditions.
Zhan, Zhenzhen,Ma, Haojie,Cui, Xinfeng,Jiang, Pengbo,Pu, Jinghong,Zhang, Yixin,Huang, Guosheng
p. 5148 - 5152
(2019/06/03)

A Reusable Cobalt Catalyst for Reversible Acceptorless Dehydrogenation and Hydrogenation of N-Heterocycles
The development of robust catalytic systems based on base-metals for reversible acceptorless dehydrogenation (ADH) and hydrogenation of feedstock chemicals is very important in the context of ‘hydrogen storage’. Herein, we report a highly efficient reusable cobalt-based heterogeneous catalyst for reversible dehydrogenation and hydrogenation of N-heterocycles. Both the ADH and the hydrogenation processes operate under mild, benign conditions.
Jaiswal, Garima,Subaramanian, Murugan,Sahoo, Manoj K.,Balaraman, Ekambaram
p. 2449 - 2457
(2019/05/10)

Room temperature catalytic dehydrogenation of cyclic amines with the liberation of H2 using water as a solvent
Catalytic dehydrogenation of cyclic amines, in particular partially saturated N-heterocycles to N-heterocyclic arenes, with the removal of molecular hydrogen as the sole byproduct in water is reported. This dehydrogenation reaction proceeds smoothly under very mild and benign conditions and operates at room temperature. This distinctive reactivity has been achieved under dual catalytic conditions by merging the visible-light active [Ru(bpy)3]2+ as the photoredox catalyst and a newly synthesized cobalt complex as the proton-reduction catalyst. A detailed mechanistic study (control experiments, electrochemical studies, UV-visible experiments) is presented for the present dual catalysis.
Sahoo, Manoj K.,Balaraman, Ekambaram
supporting information
p. 2119 - 2128
(2019/04/26)

2-Iodo benzoic acid: An unconventional precursor for the one pot multi-component synthesis of quinoxaline using organo Cu (II) catalyst
This is the first reported, unconventional, efficient strategy for the synthesis of quinoxaline from 2 to iodo benzoic acid and sodium azide in presence of organo Cu (II) catalyst. Herein, a very simple, versatile one pot multi-component protocol for the synthesis of biologically active compound, quinoxaline has been described via Schmidt reaction and the nucleophilic substitution reaction. The isolated compounds were characterized by 1H NMR, 13C NMR. Our reported organo catalyst was characterized by single crystal XRD, SEM.
Saha, Bittu,Mitra, Bijeta,Brahmin, Dhiraj,Sinha, Biswajit,Ghosh, Pranab
supporting information
p. 3657 - 3663
(2018/09/12)

C-N Bond Formation Catalyzed by Ruthenium Nanoparticles Supported on N-Doped Carbon via Acceptorless Dehydrogenation to Secondary Amines, Imines, Benzimidazoles and Quinoxalines
Ruthenium nanoparticles (NPs) supported on N-doped carbon (Ru/N?C) were prepared by the pyrolysis of cis-Ru(phen)2Cl2 loaded onto carbon powder (VULCAN XC72R) at 800 °C. Ru/N?C NPs (0.2 mol% Ru) selectively catalyzed either acceptorless dehydrogenation coupling (ADC) or auto-transfer-hydrogen (ATH) reactions of amines with alcohols to imines and secondary amines. Such selectivity could be controlled by the choice of alkali metal ion associated with the base. Under similar catalytic conditions, the ADC cross-coupling of diamines with primary alcohols or diols afforded the corresponding benzimidazoles and quinoxalines in good to excellent yields. This catalytic system displayed good activity, recyclability, and wide applicability to a diverse range of substrates.
Guo, Bin,Li, Hong-Xi,Zhang, Shi-Qi,Young, David James,Lang, Jian-Ping
p. 5627 - 5636
(2018/12/04)

Cobalt complex catalyzed atom-economical synthesis of quinoxaline, quinoline and 2-alkylaminoquinoline derivatives
A new phosphine-free Co(ii) complex-catalyzed synthesis of various quinoxalines via dehydrogenative coupling of vicinal diols with both o-phenylenediamines and 2-nitroanilines is reported. This complex was also effective for the synthesis of quinolines. The practical aspect of this catalytic system was revealed by the one-pot synthesis of 2-alkylaminoquinolines.
Shee, Sujan,Ganguli, Kasturi,Jana, Kalipada,Kundu, Sabuj
supporting information
p. 6883 - 6886
(2018/06/26)

Synthesis of Pyrazines and Quinoxalines via Acceptorless Dehydrogenative Coupling Routes Catalyzed by Manganese Pincer Complexes
Base-metal catalyzed dehydrogenative self-coupling of 2-amino alcohols to selectively form functionalized 2,5-substituted pyrazine derivatives is presented. Also, 2-substituted quinoxaline derivatives are synthesized by dehydrogenative coupling of 1,2-diaminobenzene and 1,2-diols. In both cases, water and hydrogen gas are formed as the sole byproducts. The reactions are catalyzed by acridine-based pincer complexes of earth-abundant manganese.
Daw, Prosenjit,Kumar, Amit,Espinosa-Jalapa, Noel Angel,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
p. 7734 - 7741
(2018/08/03)

Phosphine free Mn-complex catalysed dehydrogenative C-C and C-heteroatom bond formation: A sustainable approach to synthesize quinoxaline, pyrazine, benzothiazole and quinoline derivatives
Herein the first sustainable synthesis of quinoxalines, pyrazines and benzothiazoles catalysed by a phosphine free Mn(i) complex via acceptorless dehydrogenative coupling (ADC) is reported. This method is also applied successfully to synthesize quinolines via the dehydrogenation (removal of H2) and condensation (removal of H2O) reaction between 2-aminobenzyl alcohols and secondary alcohols.
Das, Kalicharan,Mondal, Avijit,Srimani, Dipankar
supporting information
p. 10582 - 10585
(2018/09/25)

Ball-milling synthesized hydrotalcite supported Cu-Mn mixed oxide under solvent-free conditions: An active catalyst for aerobic oxidative synthesis of 2-acylbenzothiazoles and quinoxalines
A rapid solvent-free ball-milling method was developed to prepare a hydrophobic hydrotalcite supported Cu-Mn mixed oxide catalyst (Cu-Mn/HT). The mechanochemically prepared catalyst exhibited high catalytic activity and recyclability towards the aerobic synthesis of 2-acylbenzothiazoles and quinoxalines in green medium ethanol compared with the ones synthesized via grinding and wet-impregnation. Moreover, control experiments showed that the catalyst was successfully used in green oxidative esterification and coupling as well. Cu-Mn/HT was characterized by BET, ICP, XRD, XPS, SEM and TEM, which indicated that more surface oxygen vacancies and formed CuMn2O4 species on HT might contribute to the catalytic activity.
Meng, Xu,Bi, Xiuru,Yu, Chaoying,Chen, Gexin,Chen, Baohua,Jing, Zhenqiang,Zhao, Peiqing
supporting information
p. 4638 - 4644
(2018/10/23)

Green and Eco-Friendly Synthesis of Quinoxalines by Br?nsted Acidic Ionic Liquid Supported on Nano-SiO2 under Solvent-Free Conditions
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Daragahi, Seyed Arash Hosseini,Mohebat, Razieh,Mosslemin, Mohammad Hossein
p. 301 - 313
(2018/05/29)