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Metal-Free Hydroxymethylation of Indole Derivatives with Formic Acid as an Alternative Way to Indirect Utilization of CO2
The selective N-alkylation of indole substrates remains an ongoing research challenge for the relative attenuated nucleophilicity toward nitrogen. Herein, we developed the hydroxymethylation of indole derivatives to afford N-alkylated indole products with
Huang, Wen-Bin,Yang, Meng,He, Liang-Nian
p. 3775 - 3779
(2022/02/10)

Visible-Light- And PPh3-Mediated Direct C-N Coupling of Nitroarenes and Boronic Acids at Ambient Temperature
We present here a metal-free, visible-light- and triphenylphosphine-mediated intermolecular, reductive amination between nitroarenes and boronic acids at ambient temperature without any photocatalyst. Mechanistically, a slow reduction of nitroarenes to a nitroso and, finally, a nitrene intermediate occurs that leads to the amination product with concomitant 1,2-aryl/-alkyl migration from a boronate complex. A wide range of nitroarenes underwent C-N coupling with aryl-/alkylboronic acids providing high yields.
Manna, Kartic,Ganguly, Tanusree,Baitalik, Sujoy,Jana, Ranjan
supporting information
p. 8634 - 8639
(2021/11/01)

Preparation method of 3 - bromo - N - phenyl carbazole
The invention relates to a preparation method of 3 -bromo - N -phenyl carbazole, and belongs to the technical field of organic chemistry. To the invention, diphenylamine serves as a starting raw material, and 2 -bromophenylaniline is obtained through bromination reaction. Then, intramolecular cyclization is carried out to obtain carbazole. Then, 3 - bromocarbazole is obtained by bromination reaction. Finally, a substituted 3 - bromo - N -phenyl carbazole is obtained. By controlling the concentration and reaction environment of the reactants, the selectivity of the reaction site is effectively improved, the used raw materials are simple and easy to obtain, the preparation period is relatively short, and the reaction process is simple and easy to control.
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(2021/10/11)

Quinoline Ligands Improve the Classic Direct C?H Functionalisation/Intramolecular Cyclisation of Diaryl Ethers to Dibenzofurans
The C?H functionalisation approach to the synthesis of dibenzofurans is hampered by a number of problems. Herein we describe the evolution of a cheap, bench stable quinoline ligand, which obviates most of the current limitations and allows for a high yielding synthesis of a range of valuable dibenzofurans. Dibenzofurans are important motifs in natural products and compounds with wide biological activity.
Mackey, Katrina,Jones, David J.,Pardo, Leticia M.,McGlacken, Gerard P.
supporting information
p. 495 - 498
(2021/01/12)

Electrochemical Palladium-Catalyzed Intramolecular C—H Amination of 2-Amidobiaryls for Synthesis of Carbazoles
The synthesis of carbazoles based on the electrochemical Pd-catalyzed intramolecular C—H amination of 2-amidobiaryls through oxidative cross coupling has been achieved under mild reaction conditions. The reaction can be carried out in undivided cell without the addition of external chemical oxidant. Besides good functional group compatibility, the desired carbazoles can be scaled up and modified easily. Compared with previous methods, this protocol affords a simple and sustainable avenue for the construction of carbazoles.
Gao, Xinlong,Lei, Aiwen,Wang, Pan,Wang, Qingqing,Zhang, Heng,Zhang, Xiaojing
supporting information
p. 143 - 148
(2020/12/18)

The benzyl can be selectively removed by visible light or near visible light. Method for protecting allyl and propargyl group
The invention provides a method for selectively removing benzyl, allyl and propargyl protecting groups by visible light or near visible light, namely a substrate containing benzyl, allyl or propargyl protecting groups. The method has the advantages of simple operation, safe and clean visible light or near visible light as excitation conditions, cheap and easily available reagents, high reaction yield, high reaction chemistry and regional selectivity, and is suitable for selective removal of benzyl, allyl and propargyl protecting groups in various substrates.
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(2021/10/16)

Visible-light-driven Cadogan reaction
Visible-light-driven photochemical Cadogan-type cyclization has been discovered. The organic D-A type photosensitizer 4CzIPN found to be an efficient mediator to transfer energy from photons to the transient intermediate that breaks the barriers of deoxygenation in Cadogan reaction and enables a mild metal-free access to carbazoles and related heterocycles. DFT calculation results indicate mildly endergonic formation of the intermediate complex of nitrobiarenes and PPh3, which corresponds with experimental findings regarding reaction temperature. The robust synthetic capacity of the photoredox Cadogan reaction systems has been demonstrated by the viable productivity of a broad range of carbazoles and related N-heterocycles with good tolerance of various functionalities.
Qu, Zhonghua,Wang, Pu,Chen, Xing,Deng, Guo-Jun,Huang, Huawen
supporting information
p. 2582 - 2586
(2021/03/09)

NaI/PPh3-Mediated Photochemical Reduction and Amination of Nitroarenes
A mild transition-metal- and photosensitizer-free photoredox system based on the combination of NaI and PPh3 was found to enable highly selective reduction of nitroarenes. This protocol tolerates a broad range of reducible functional groups such as halogen (Cl, Br, and even I), aldehyde, ketone, carboxyl, and cyano. Moreover, the photoredox catalysis with NaI and stoichiometric PPh3 provides also an alternative entry to Cadogan-type reductive amination when o-nitrobiarenes were used.
Qu, Zhonghua,Chen, Xing,Zhong, Shuai,Deng, Guo-Jun,Huang, Huawen
supporting information
p. 5349 - 5353
(2021/07/21)

Convenient One-Pot Synthesis of 9 H -Carbazoles by Microwave Irradiation Employing a Green Palladium-Based Nanocatalyst
An efficient palladium-catalyzed tandem reaction for the one-pot synthesis of 9 H -carbazoles under microwave irradiation is developed. This approach involves a sequential Buchwald-Hartwig amination and a direct arylation from affordable and inexpensive anilines and 1,2-dihaloarenes. For the development of this purpose, a novel and magnetically recoverable palladium nanocatalyst supported on a green biochar under ligand-free conditions is used. Compared to other existing palladium-based protocols, the present synthetic methodology shows a drastic reduction in reaction times and excellent compatibility with different functional groups allowing to obtain a small library of 9 H -carbazoles in high yields and with good regioselectivity. This procedure represents the first example in the direct synthesis of carbazoles using a heterogeneous palladium nanocatalyst from commercial precursors. To examine the application of this protocol, a direct and scalable synthesis of the bioactive carbazole alkaloid clausenalene from commercially available starting materials is described.
Steingruber, H. Sebastián,Mendioroz, Pamela,Volpe, María A.,Gerbino, Darío C.
p. 4048 - 4058
(2021/08/03)

Alkyl chain regulation: distinctive odd-even effects of mechano-luminescence and room-temperature phosphorescence in alkyl substituted carbazole amide derivatives
A series of carbazole amide derivatives were synthesized by adjusting then-alkyl chain with different lengths from methyl to octyl (CAC-N,N= 1-8). Their photophysical behaviors were highly dependent on the parity of their alkyl chain. That is, compounds with even-numbered alkyl chains exhibited efficient mechanoluminescence (ML) and strong room temperature phosphorescence (RTP), however, no ML and inferior RTP were observed in the odd-numbered counterparts. To make the results more clear, the important starting material, carbazole, was synthesized in the lab, from which, all the above eight carbazole amide derivatives were re-synthesized for comparison. Although RTP properties were disturbed by impurities in commercial carbazole, the ML property remained unchanged. Single crystal analyses revealed that the crosslink network and isolated dimers were formed in even- and odd-numbered CAC crystals respectively through hydrogen-bond interactions, which should account for the odd-even alternating ML phenomena. Additionally, multicolor ML from blue to red was realized by doping various organic dyes in the ML host matrix of CAC-8. To the best of our knowledge, this work is the first observation of parity effects in the ML property.
Che, Weilong,Li, Shuhui,Li, Xiaoning,Li, Zhen,Tu, Liangjing,Xie, Yujun
supporting information
p. 12124 - 12132
(2021/09/30)

Method for synthesizing organic aromatic nitrogen-containing compound by taking nitrogen as nitrogen source
The invention provides a method for synthesizing an organic aromatic nitrogen-containing compound by taking nitrogen as a nitrogen source, and belongs to the field of organic synthesis. The invention provides a method for synthesizing an organic aromatic nitrogen-containing compound by taking nitrogen as a nitrogen source, which is characterized by comprising the following steps of: 1, reducing nitrogen by lithium powder to form lithium nitride; and 2, reacting the lithium nitride with a halogenated aromatic compound under the action of a transition metal catalyst, a ligand, alkali and a phase transfer catalyst to obtain an organic aromatic nitrogen-containing compound; wherein the two steps of reactions are completed in one pot. The method realizes the conversion of cheap nitrogen to the high-added-value aromatic nitrogen-containing compound, and also has the advantages of mild reaction conditions, good compatibility of substrate functional groups, high yield and the like.
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(2021/05/08)

Ceramic boron carbonitrides for unlocking organic halides with visible light
Photochemistry provides a sustainable pathway for organic transformations by inducing radical intermediates from substrates through electron transfer process. However, progress is limited by heterogeneous photocatalysts that are required to be efficient, stable, and inexpensive for long-term operation with easy recyclability and product separation. Here, we report that boron carbonitride (BCN) ceramics are such a system and can reduce organic halides, including (het)aryl and alkyl halides, with visible light irradiation. Cross-coupling of halides to afford new C-H, C-C, and C-S bonds can proceed at ambient reaction conditions. Hydrogen, (het)aryl, and sulfonyl groups were introduced into the arenes and heteroarenes at the designed positions by means of mesolytic C-X (carbon-halogen) bond cleavage in the absence of any metal-based catalysts or ligands. BCN can be used not only for half reactions, like reduction reactions with a sacrificial agent, but also redox reactions through oxidative and reductive interfacial electron transfer. The BCN photocatalyst shows tolerance to different substituents and conserved activity after five recycles. The apparent metal-free system opens new opportunities for a wide range of organic catalysts using light energy and sustainable materials, which are metal-free, inexpensive and stable. This journal is
Yuan, Tao,Zheng, Meifang,Antonietti, Markus,Wang, Xinchen
p. 6323 - 6332
(2021/05/19)

Synthesis of indenones through rhodium(III)-catalyzed [3+2] annulation utilizing a recyclable carbazolyl leaving group
The rhodium(III)-catalyzed annulative coupling of 9-ben-zoylcarbazoles with internal alkynes proceeds efficiently through ortho CH and CN bond cleavages. This reaction provides direct access to variously substituted indanone derivatives. The carbazolyl leaving group can be readily recovered and reused for preparing the starting materials.
Ochiai, Shiho,Sakai, Asumi,Usuki, Yoshinosuke,Kang, Bubwoong,Shinada, Tetsuro,Satoh, Tetsuya
supporting information

(2021/04/23)

Synthesis of Indoles by Reductive Cyclization of Nitro Compounds Using Formate Esters as CO Surrogates
Alkyl and aryl formate esters were evaluated as CO sources in the Pd- and Pd/Ru-catalyzed reductive cyclization of 2-nitrostyrenes to give indoles. Whereas the use of alkyl formates requires the presence of a ruthenium catalyst such as Ru3(CO)12, the reaction with phenyl formate can be performed by using a Pd/phenanthroline complex alone. Phenyl formate was found to be the most effective CO source and the desired products were obtained in excellent yields, often higher than those previously reported using pressurized CO. The reaction tolerates many functional groups, including sensitive ones like a free aldehydic group or a pendant pyrrole. Detailed experiments and kinetic studies allow to conclude that the activation of phenyl formate is base-catalyzed and that the metal doesn't play a role in the decarbonylation step. The reactions can be performed in a single thick-walled glass tube with as little as 0.2 mol-% palladium catalyst and even on a 2 g scale. The same protocol can be extended to other nitro compounds, affording different heterocycles.
Ahmed Fouad, Manar,Ferretti, Francesco,Formenti, Dario,Milani, Fabio,Ragaini, Fabio
supporting information
p. 4876 - 4894
(2021/09/20)

An Improved PIII/PV=O-Catalyzed Reductive C-N Coupling of Nitroaromatics and Boronic Acids by Mechanistic Differentiation of Rate- And Product-Determining Steps
Experimental, spectroscopic, and computational studies are reported that provide an evidence-based mechanistic description of an intermolecular reductive C-N coupling of nitroarenes and arylboronic acids catalyzed by a redox-active main-group catalyst (1,2,2,3,4,4-hexamethylphosphetane P-oxide, i.e., 1·[O]). The central observations include the following: (1) catalytic reduction of 1·[O] to PIII phosphetane 1 is kinetically fast under conditions of catalysis; (2) phosphetane 1 represents the catalytic resting state as observed by 31P NMR spectroscopy; (3) there are no long-lived nitroarene partial-reduction intermediates observable by 15N NMR spectroscopy; (4) the reaction is sensitive to solvent dielectric, performing best in moderately polar solvents (viz. cyclopentylmethyl ether); and (5) the reaction is largely insensitive with respect to common hydrosilane reductants. On the basis of the foregoing studies, new modified catalytic conditions are described that expand the reaction scope and provide for mild temperatures (T ≥ 60 °C), low catalyst loadings (≥2 mol%), and innocuous terminal reductants (polymethylhydrosiloxane). DFT calculations define a two-stage deoxygenation sequence for the reductive C-N coupling. The initial deoxygenation involves a rate-determining step that consists of a (3+1) cheletropic addition between the nitroarene substrate and phosphetane 1; energy decomposition techniques highlight the biphilic character of the phosphetane in this step. Although kinetically invisible, the second deoxygenation stage is implicated as the critical C-N product-forming event, in which a postulated oxazaphosphirane intermediate is diverted from arylnitrene dissociation toward heterolytic ring opening with the arylboronic acid; the resulting dipolar intermediate evolves by antiperiplanar 1,2-migration of the organoboron residue to nitrogen, resulting in displacement of 1·[O] and formation of the target C-N coupling product upon in situ hydrolysis. The method thus described constitutes a mechanistically well-defined and operationally robust main-group complement to the current workhorse transition-metal-based methods for catalytic intermolecular C-N coupling.
Li, Gen,Nykaza, Trevor V.,Cooper, Julian C.,Ramirez, Antonio,Luzung, Michael R.,Radosevich, Alexander T.
supporting information
p. 6786 - 6799
(2020/04/30)

A NaH-promoted N-detosylation reaction of diverse p-toluenesulfonamides
A NaH-mediated detosylation reaction of various Ts-protected indoles, azaheterocycles, anilines and dibenzylamine was reported. The method features cheap reagent, convenient operations, mild reaction conditions and broad substrate scope. Moreover, this study revealed that the loading of NaH in tosylation reactions of nitrogen-containing compounds with NaH as a base in DMA or DMF should be controlled due to the possibility of adverse detosylation.
Sun, Wanwan,Chen, Xiaobei,Hu, Ying,Geng, Huihui,Jiang, Yuanrui,Zhou, Yuxin,Zhu, Wenjing,Hu, Min,Hu, Haohua,Wang, Xingyi,Wang, Xinli,Zhang, Shilei,Hu, Yanwei
supporting information

(2020/10/05)

Electron Transfer Photoredox Catalysis: Development of a Photoactivated Reductive Desulfonylation of an Aza-Heteroaromatic Ring
Herein, we report a protocol for desulfonylation of aza-heteroaromatic rings via photoinduced electron transfer and hydrogen atom transfer. This general protocol has a wide substrate range and moderate to good yields. The utility of the method was demonstrated by the chemoselective desulfonylation of a molecule containing both an aliphatic and an aromatic sulfonamide. (Figure presented.).
Qiang-Liu,Liu, Yu-Xiu,Song, Hong-Jian,Wang, Qing-Min
supporting information
p. 3110 - 3115
(2020/07/04)

Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor
Novel approaches for N- and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KOtBu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KOtBu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.
Heredia, Micaela D.,Guerra, Walter D.,Barolo, Silvia M.,Fornasier, Santiago J.,Rossi, Roberto A.,Budén, Mariá E.
supporting information
p. 13481 - 13494
(2020/12/15)

Dual palladium-photoredox catalyzed chemoselective C-H arylation of phenylureas
A highly chemoselective C-H arylation of phenylureas has been accomplished using dual palladium-photoredox catalysis at room temperature without any additives, base or external oxidants. Regioselective C-H arylation ofN,N'-diaryl substituted unsymmetrical phenylureas has also been accomplished by a careful choice of aryl groups.
Babu, Sakamuri Sarath,Shahid,Gopinath, Purushothaman
p. 5985 - 5988
(2020/06/04)

Achieving Purely-Organic Room-Temperature Aqueous Phosphorescence via a Two-Component Macromolecular Self-Assembly Strategy
Manipulation of supramolecular behaviors and aggregation states represents an important topic in devising intriguing photofunctional systems. Here we report a two-component macromolecular self-assembly strategy for achieving aqueous room-temperature phosphorescence (RTP) in purely organic systems. Amphiphilic triblock copolymers are used to modulate the self-assembly of planar RTP molecules in aqueous solution, leading to the formation of sheet-like RTP objects with well-defined morphology, uniform crystalline nanostructures and excellent aqueous dispersity. In contrast, the addition of the planar RTP molecules into aqueous medium only leads to precipitation and quenching of RTP properties. Powder X-ray diffraction and single-crystal X-ray diffraction studies reveal that the amphiphilic triblock copolymers can assist supramolecular columnar packing of the planar RTP molecules where multiple non-covalent interactions stabilize the triplet excited states. Interestingly, it is found that luminescent signals of the sheet-like RTP objects can be extracted from strong fluorescent environments by phosphorescence mode and emission lifetime measurement.
Guo, Wang,Wang, Xuepu,Zhou, Bei,Zhang, Kaka
p. 3469 - 3474
(2020/10/02)

Self-Assembled Helical Arrays for the Stabilization of the Triplet State
Room-temperature phosphorescence of metal and heavy atom-free organic molecules has emerged as an area of great potential in recent years. A rational design played a critical role in controlling the molecular ordering to impart efficient intersystem crossing and stabilize the triplet state to achieve room-temperature ultralong phosphorescence. However, in most cases, the strategies to strengthen phosphorescence efficiency have resulted in a reduced lifetime, and the available nearly degenerate singlet-triplet energy levels impart a natural competition between delayed fluorescence and phosphorescence, with the former one having the advantage. Herein, an organic helical assembly supports the exhibition of an ultralong phosphorescence lifetime. In contrary to other molecules, 3,6-phenylmethanone functionalized 9-hexylcarbazole exhibits a remarkable improvement in phosphorescence lifetime (>4.1 s) and quantum yield (11 percent) owing to an efficient molecular packing in the crystal state. A right-handed helical molecular array act as a trap and exhibits triplet exciton migration to support the exceptionally longer phosphorescence lifetime.
Babu, Sukumaran Santhosh,Chaubey, Shailendra Kumar,Gonnade, Rajesh G.,Goudappagouda,Krishnan, Retheesh,Kumar, G. V. Pavan,Mohana Kumari, Divya S.,Nayak, Rashmi,Nidhankar, Aakash D.
supporting information
p. 13079 - 13085
(2020/06/10)

Self-Assembled Multilayer Iron(0) Nanoparticle Catalyst for Ligand-Free Carbon-Carbon/Carbon-Nitrogen Bond-Forming Reactions
Self-assembled multilayer iron(0) nanoparticles (NPs, 6-10 nm), namely, sulfur-modified Au-supported Fe(0) [SAFe(0)], were developed for ligand-free one-pot carbon-carbon/carbon-nitrogen bond-forming reactions. SAFe(0) was successfully prepared using a well-established metal-nanoparticle catalyst preparative protocol by simultaneous in situ metal NP and nanospace organization (PSSO) with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (Si-DHP) as a strong reducing agent. SAFe(0) was easy to handle in air and could be recycled with a low iron-leaching rate in reaction cycles.
Akiyama, Toshiki,Arisawa, Mitsuhiro,Haneoka, Hitoshi,Harada, Kazuo,Hasegawa, Jun-Ya,Honma, Tetsuo,Mashima, Kazushi,Sato, Yoshihiro,Shimoda, Shuhei,Shio, Yasunori,Suzuki, Takeyuki,Tamenori, Yusuke,Tsurugi, Hayato,Tsuruta, Kazuki,Wada, Yuki,Yamada, Makito
p. 7244 - 7249
(2020/10/12)

Synthesis of Carbazoles and Related Heterocycles from Sulfilimines by Intramolecular C?H Aminations
While direct nitrene insertions into C?H bonds have become an important tool for building C?N bonds in modern organic chemistry, the generation of nitrene intermediates always requires transition metals, high temperatures, ultraviolet or laser light. We report a mild synthesis of carbazoles and related building blocks through a visible light-induced intramolecular C?H amination reaction. A striking advantage of this new method is the use of more reactive aryl sulfilimines instead of the corresponding hazardous azides. Different catalysts and divergent light sources were tested. The reaction scope is broad and the product yield is generally high. An efficient gram-scale synthesis of Clausine C demonstrates the applicability and scalability of this new method.
Hashmi, A. Stephen K.,Song, Lina,Tian, Xianhai
p. 12342 - 12346
(2020/05/19)

Heterogeneous photocatalysis of azides: Extending nitrene photochemistry to longer wavelengths
The photodecomposition of azides to generate nitrenes usually requires wavelengths in the 300 nm region. In this study, we show that this reaction can be readily performed in the UVA region (368 nm) when catalyzed by Pd-decorated TiO2. In aqueous medium the reaction leads to amines, with water acting as the H source; however, in non-protic and non-nucleophilic media, such as acetonitrile, nitrenes recombine to yield azo compounds, while azirine-mediated trapping occurs in the presence of nucleophiles. The heterogeneous process facilitates catalyst separation while showing great chemoselectivity and high yields.
Argüello, Juan E.,Lanterna, Anabel E.,Lemir, Ignacio D.,Scaiano, Juan C.
supporting information
p. 10239 - 10242
(2020/10/02)

Dearomatization-Rearomatization Strategy for Synthesizing Carbazoles with 2,2′-Biphenols and Ammonia by Dual C(Ar)-OH Bond Cleavages
Carbazole is an essential building block in various pharmaceuticals, agrochemicals, natural products, and materials. For future sustainability, it is highly desirable to synthesize carbazole derivatives directly from renewable resources or cheap raw materials. Phenolic compounds are a class of degradation products of lignin. On the other hand, ammonia is a very cheap industrial inorganic chemical. Herein, an efficient dearomatization-rearomatization strategy has been developed to directly cross-couple 2,2′-biphenols with ammonia by dual C(Ar)-OH bond cleavages. This strategy provides a greener pathway to synthesize valuable carbazole derivatives from phenols.
Cao, Dawei,Yu, Jing,Zeng, Huiying,Li, Chao-Jun
p. 13200 - 13205
(2020/12/18)

Preparation and application of triphenylphosphine allyl palladium halide compound and derivative thereof
The invention discloses a synthesis method of a triphenylphosphine allyl palladium halide compound and a derivative thereof. The synthesis method comprises the step of carrying out one-step reaction on a mixture containing a palladium salt, a halogenated allyl compound and a trisubstituted phosphine compound to obtain the triphenylphosphine allyl palladium halide compound and the derivative thereof. The method is low in cost, high in efficiency, easy to operate and high in safety. The prepared triphenylphosphine allyl palladium halide compound and the derivative thereof can be widely applied as catalysts to catalytic cross coupling or homogeneous coupling reactions of various types of organic substrates so as to prepare various organic reaction intermediates.
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(2020/05/30)

Visible-Light-Induced, Base-Promoted Transition-Metal-Free Dehalogenation of Aryl Fluorides, Chlorides, Bromides, and Iodides
We report a simple and efficient visible-light-induced transition-metal-free hydrogenation of aryl halides. The combined visible light and base system is used to initiate the desired radical-mediated hydrogenation. A variety of aryl fluorides, chlorides, bromides, and iodides could be reduced to the corresponding (hetero)arenes with excellent yields under mild conditions. Various functional groups and other heterocyclic compounds are tolerated.
Ding, Ting-Hui,Qu, Jian-Ping,Kang, Yan-Biao
supporting information
p. 3084 - 3088
(2020/04/10)

Site-Specific Synthesis of Carbazole Derivatives through Aryl Homocoupling and Amination
We synthesized various carbazoles from anilines through a three-step process with good overall yields (up to 48percent). This process comprises N -acetylation, copper(0)-mediated Ullmann homocoupling, and acid-mediated intramolecular amination. It permits various functional groups on the substrate. Scale-up of the developed three-step synthetic route to carbazoles was also demonstrated.
Baek, Junghyun,Ban, Jaeyoung,Lim, Minkyung,Rhee, Hakjune,Shabbir, Saira
p. 917 - 927
(2020/03/13)

Combined KOH/BEt3Catalyst for Selective Deaminative Hydroboration of Aromatic Carboxamides for Construction of Luminophores
The selective catalytic C-N bond cleavage of amides into value-added amine products is a desirable but challenging transformation. Molecules containing iminodibenzyl motifs are prevalent in pharmaceutical molecules and functional materials. Here we established a combined KOH/BEt3 catalyst for deaminative hydroboration of acyl-iminodibenzyl derivatives, including nonheterocyclic carboxamides, to the corresponding amines. This novel transition-metal-free methodology was also applied to the construction of Clomipramine and luminophores.
Li, Jinshan,Wang, Jiali,Yang, Jianguo,Yao, Wubing,Zhong, Aiguo
supporting information
p. 8086 - 8090
(2020/11/03)

In Crystallo Snapshots of Rh2-Catalyzed C-H Amination
While X-ray crystallography routinely provides structural characterization of kinetically stable pre-catalysts and intermediates, elucidation of the structures of transient reactive intermediates, which are intimately engaged in bond-breaking and -making
Das, Anuvab,Wang, Chen-Hao,Van Trieste, Gerard P.,Sun, Cheng-Jun,Chen, Yu-Sheng,Reibenspies, Joseph H.,Powers, David C.
supporting information
p. 19862 - 19867
(2021/01/01)

Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes
An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.
Kawauchi, Daichi,Noda, Kenta,Komatsu, Yoshiyuki,Yoshida, Kei,Ueda, Hirofumi,Tokuyama, Hidetoshi
p. 15793 - 15798
(2020/10/12)

Synergistic combination of visible-light photo-catalytic electron and energy transfer facilitating multicomponent synthesis of β-functionalized α,α-diarylethylamines
A synthetic strategy with the visible-light photo-catalytic synergistic combination of electron and energy transfer processes has been developed. The mild reaction conditions allow the radical-radical cross-coupling phenomenon for the multicomponent synthesis of β-arylsulfonyl(diarylphosphinoyl)-α,α-diarylethyl-amines from readily available arylsulfinic acids (diarylphosphine oxides), 1,1-diarylethylenes and arylazides.
Wu, Yanan,Zhang, Yipin,Jiang, Mingjie,Dong, Xunqing,Jalani, Hitesh B.,Li, Guigen,Lu, Hongjian
supporting information
p. 6405 - 6408
(2019/06/07)

Hydride-catalyzed selectively reductive cleavage of unactivated tertiary amides using hydrosilane
The first hydride-catalyzed reductive cleavage of various unactivated tertiary amides, including the biologically active aryl-phenazine carboxamides and the challenging non-heterocyclic carbonyl functions, using low-cost hydrosilane as a reducing reagent has been developed. The novel catalyst system exhibits high efficiency and exclusive selectivity, providing the desired amines in useful to excellent yields under mild conditions. Overall, this transition metal-free process may offer a versatile alternative to currently employed expensive reducing reagents, high-pressure hydrogen or metal systems for the selective reductive cleavage of amides.
Yao, Wubing,Li, Rongrong,Yang, Jianguo,Hao, Feiyue
p. 3874 - 3878
(2019/08/07)

CARBAZOLE DERIVATIVE AND BIPHENYL DERIVATIVE PRODUCTION METHOD AND NOVEL BIPHENYL DERIVATIVE
PROBLEM TO BE SOLVED: To provide a method for high-yield mass production of a carbazole derivative by a simple process using inexpensive materials. SOLUTION: A method for producing a carbazole derivative represented by general formula (3) comprises reacting an aminating agent with a 2,2'-dihydroxybiphenyl derivative represented by general formula (1). SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
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(2019/05/21)

Three Ways Isolable Carbenes Can Modulate Emission of NH-Containing Fluorophores
Fluorescent molecules and materials that exhibit emission changes in response to analytes are of great interest across multiple disciplines. Herein, we investigate the response of NH-containing fluorophores carbazole and 2-phenylbenzimidazole (Ph-BIM) with two representative isolable singlet carbenes. Specifically, N-heterocyclic carbene 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and cyclic (alkyl)(amino)carbene (2,6-diisopropylphenyl)-4,4-diethyl-2,2-dimethyl-pyrrolidin-5-ylidene (EtCAAC) were discovered to afford three different types of reaction products with carbazole and Ph-BIM. Depending on the reaction pair, hydrogen bonding (1), NH-insertion (2,3), or proton transfer (4) products can be isolated, each displaying variable photophysical responses. These products have been structurally authenticated by single crystal X-ray diffraction and NMR spectrometric methods. Studies of the solution state behavior of 1-4 reveals that these adducts are labile and can reversibly dissociate to free carbenes and fluorophores to varying extents. These equilibria produce concentration dependent solution state behavior as identified and quantified via UV-visible absorption, emission, 1H DOSY, and NMR spectroscopic measurements.
Kieser, Jerod M.,Kinney, Zacharias J.,Gaffen, Joshua R.,Evariste, Sloane,Harrison, Alexandra M.,Rheingold, Arnold L.,Protasiewicz, John D.
supporting information
p. 12055 - 12063
(2019/08/20)

Synthesis, Isolation, and Characterization of Mono- and Bis-norbornene-Annulated Biarylamines through Pseudo-Catellani Intermediates
A palladium-catalyzed C-H functionalization of an external ring of N-acyl 2-aminobiaryl with bicyclo[2.2.1]hept-2-ene (norbornene) via multiple C-H bond activations was developed. This study is the first report of the formation of bis-norbornene annulated biarylamines isomers (syn-3a′/anti-3a′ = 36:64) from multiple C-H bond functionalizations. Additionally, nondirected C-H bond functionalization at the C-4′ position with alkenes rendered complete C-H functionalization of five C-H bonds that formed a stable hexasubstituted benzene ring.
Annamalai, Pratheepkumar,Hsiao, Huan-Chang,Raju, Selvam,Fu, Yi-Hsuan,Chen, Pei-Ling,Horng, Jia-Cherng,Liu, Yi-Hung,Chuang, Shih-Ching
supporting information
p. 1182 - 1186
(2019/02/14)

Pd-Catalyzed Denitrative Intramolecular C-H Arylation
A Pd-catalyzed intramolecular C-H arylation of nitroarenes has been developed. Nitroarenes bearing tethered aryl groups at the ortho-position can be readily prepared in one step from 2-halonitroarenes by a nucleophilic aromatic substitution (SNAr). Under Pd/BrettPhos catalysis, activations of the C-NO2 bond as well as the C-H bond on arenes generated the corresponding biaryl linkage in moderate to excellent yields.
Asahara, Kitty K.,Okita, Toshimasa,Saito, Ami N.,Muto, Kei,Nakao, Yoshiaki,Yamaguchi, Junichiro
supporting information
p. 4721 - 4724
(2019/06/17)

Synthesis of N-Alkyl and N-H-Carbazoles through SNAr-Based Aminations of Dibenzothiophene Dioxides
Alkyl amines have become available for the synthesis of diverse N-alkyl carbazoles through twofold SNAr aminations of dibenzothiophene dioxides by using alkali metal bases. Of particular importance is the choice of counter cations on alkali metal bases, that is, i) the use of Li base for the efficient intermolecular reaction and ii) the sequential addition of heavier alkali metal bases (Na, K, or Cs) to promote intramolecular cyclization in a one-pot manner. This protocol also enables the cascade synthesis of N-H-carbazoles by using 2-phenylethylamine by removal of the 2-phenethyl group from N-(2-phenethyl) carbazoles in a single operation.
Kaga, Atsushi,Nogi, Keisuke,Yorimitsu, Hideki
supporting information
p. 14780 - 14784
(2019/11/13)

Molecularly Defined Manganese Catalyst for Low-Temperature Hydrogenation of Carbon Monoxide to Methanol
Methanol synthesis from syngas (CO/H2 mixtures) is one of the largest manmade chemical processes with annual production reaching 100 million tons. The current industrial method proceeds at high temperatures (200-300 °C) and pressures (50-100 atm) using a copper-zinc-based heterogeneous catalyst. In contrast, here, we report a molecularly defined manganese catalyst that allows for low-temperature/low-pressure (120-150 °C, 50 bar) carbon monoxide hydrogenation to methanol. This new approach was evaluated and optimized by quantum mechanical simulations virtual high-throughput screenings. Crucial for this achievement is the use of amine-based promoters, which capture carbon monoxide to give formamide intermediates, which then undergo manganese-catalyzed hydrogenolysis, regenerating the promoter. Following this conceptually new approach, high selectivity toward methanol and catalyst turnover numbers (up to 3170) was achieved. The proposed general catalytic cycle for methanol synthesis is supported by model studies and detailed spectroscopic investigations.
Ryabchuk, Pavel,Stier, Kenta,Junge, Kathrin,Checinski, Marek P.,Beller, Matthias
supporting information
p. 16923 - 16929
(2019/10/28)

4,4′-Bipyridyl-Catalyzed Reduction of Nitroarenes by Bis(neopentylglycolato)diboron
4,4′-Bipyridyl worked as an organocatalyst for the reduction of nitroarenes by bis(neopentylglycolato)diboron (B2nep2), followed by hydrolysis to give the corresponding anilines. This reduction proceeded under aerobic conditions without any prepurification of substrates and reagents. We found broad functional group tolerance and compatibility for O- A nd N-protecting groups under the reaction conditions. The key in this catalytic system was the addition of B2nep2 to 4,4′-bipyridyl to form N,N′-bis[(neopentylglycolato)boryl]-4,4′-bipyridinylidene as a deoxygenating reagent of nitroarenes.
Hosoya, Hiromu,Misal Castro, Luis C.,Sultan, Ibrahim,Nakajima, Yumiko,Ohmura, Toshimichi,Sato, Kazuhiko,Tsurugi, Hayato,Suginome, Michinori,Mashima, Kazushi
supporting information
p. 9812 - 9817
(2019/11/14)

Steric Effect of Carboxylate Ligands on Pd-Catalyzed Intramolecular C(sp2)–H and C(sp3)–H Arylation Reactions
A bulky carboxylic acid bearing three cyclohexylmethyl substituents at the α-position, namely, tri(cyclohexylmethyl)acetic acid, is demonstrated to act as an efficient ligand source in Pd-catalyzed intramolecular C(sp2)?H and C(sp3)?H arylation reactions. The reactions proceed smoothly under mild reaction conditions, even at room temperature due to the steric bulk of the carboxylate ligands, which accelerates the rate-determining C?H bond activation step in the catalytic cycle.
Tanji, Yutaka,Mitsutake, Naoya,Fujihara, Tetsuaki,Tsuji, Yasushi
supporting information
p. 10314 - 10317
(2018/08/06)

Nitrogen-Iodine Exchange of Diaryliodonium Salts: Access to Acridine and Carbazole
A nitrogen-iodine exchange protocol of diaryliodonium salts with sodium azide salt is developed for general construction of significant functional acridines and carbazoles, in which introduction of nitrogen at a late stage was successfully established avoiding heteroatom incompatibility. Inorganic sodium azide served as the sole nitrogen atom source in this transformation. The diversiform functional acridines and carbazoles were comprehensively achieved through annulated diaryliodonium salts, respectively. Notably, Acridine orange (a fluorescent indicator for cell lysosomal dye) and Carprofen (a nonsteroidal anti-inflammatory drug) were efficiently established through this protocol.
Wang, Ming,Fan, Qiaoling,Jiang, Xuefeng
p. 216 - 219
(2018/01/17)

Visible-light-promoted intramolecular C-H amination in aqueous solution: Synthesis of carbazoles
An effective and operationally simple protocol is reported for the synthesis of versatile carbazoles. With water as a co-solvent, visible-light rather than various metals is used to facilitate the conversion of readily available 2-azidobiphenyls under mild conditions. Various functionalized bioactive natural alkaloids, such as glycoborine, clausine C, clausine L, clausine H and clauszoline K, were synthesized efficiently with nitrogen as a sole byproduct. The reaction could be performed in water, acidic or alkaline buffer solutions, showing its potential for applications in biochemistry.
Yang, Lizheng,Zhang, Yipin,Zou, Xiaodong,Lu, Hongjian,Li, Guigen
p. 1362 - 1366
(2018/03/26)

Design, synthesis and biological evaluation of: N -arylsulfonyl carbazoles as novel anticancer agents
In this work, a set of structurally diverse synthetic carbazoles was screened for their anticancer activities. According to structure-activity relationship studies, carbazoles with an N-substituted sulfonyl group exhibited better anticancer activity. Moreover, compound 8h was discovered to show the most potent anticancer effects on Capan-2 cells by inducing apoptosis and cell cycle arrest in G2/M phase. Finally, the in vivo study demonstrated that 8h prevented the tumor growth in PANC-1 and Capan-2 xenograft models without apparent toxicity.
You, Xin,Zhu, Daqian,Lu, Wenhua,Sun, Yichen,Qiao, Shuang,Luo, Bingling,Du, Yongliang,Pi, Rongbiao,Hu, Yumin,Huang, Peng,Wen, Shijun
p. 17183 - 17190
(2018/05/28)

Biphilic Organophosphorus-Catalyzed Intramolecular Csp2-H Amination: Evidence for a Nitrenoid in Catalytic Cadogan Cyclizations
A small-ring phosphacycloalkane (1,2,2,3,4,4-hexamethylphosphetane, 3) catalyzes intramolecular C-N bond forming heterocyclization of o-nitrobiaryl and -styrenyl derivatives in the presence of a hydrosilane terminal reductant. The method provides scalable access to diverse carbazole and indole compounds under operationally trivial homogeneous organocatalytic conditions, as demonstrated by 17 examples conducted on 1 g scale. In situ NMR reaction monitoring studies support a mechanism involving catalytic PIII/PV=O cycling, where tricoordinate phosphorus compound 3 represents the catalytic resting state. For the catalytic conversion of o-nitrobiphenyl to carbazole, the kinetic reaction order was determined for phosphetane catalyst 3 (first order), substrate (first order), and phenylsilane (zeroth order). For differentially 5-substituted 2-nitrobiphenyls, the transformation is accelerated by electron-withdrawing substituents (Hammett factor ? = +1.5), consistent with the accrual of negative charge on the nitro substrate in the rate-determining step. DFT modeling of the turnover-limiting deoxygenation event implicates a rate-determining (3 + 1) cheletropic addition between the phosphetane catalyst 3 and 2-nitrobiphenyl substrate to form an unobserved pentacoordinate spiro-bicyclic dioxazaphosphetane, which decomposes via (2 + 2) cycloreversion giving 1 equiv of phosphetane P-oxide 3·[O] and 2-nitrosobiphenyl. Experimental and computational investigations into the C-N bond forming event suggest the involvement of an oxazaphosphirane (2 + 1) adduct between 3 and 2-nitrosobiphenyl, which evolves through loss of phosphetane P-oxide 3·[O] to give the observed carbazole product via C-H insertion in a nitrene-like fashion.
Nykaza, Trevor V.,Ramirez, Antonio,Harrison, Tyler S.,Luzung, Michael R.,Radosevich, Alexander T.
supporting information
p. 3103 - 3113
(2018/03/08)

Copper(II) catalyzed aromatization of tetrahydrocarbazole: An unprecedented protocol and its utility towards the synthesis of carbazole alkaloids
An efficient protocol for the aromatization of tetrahydrocarbazole is described by using catalytic copper(II) chloride dihydrate in DMSO. This newly established methodology has utilized towards the synthesis of naturally occurring carbazole alkaloids, namely 3-methylcarbazole, 3-formyl carbazole, glycozoline, glycozolicine and clauszoline-K. In addition, the protocol is generalized for the aromatization of N-substituted tetrahydrocarbazole, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroisoquinoline and 1,2,3,4-tetrahydro β-carboline to give the corresponding heteroaromatic compounds from very good to excellent yield. Moreover, this method has been proven to be tolerant to a broad range of functional groups with excellent yields.
Dalvi, Bhakti A.,Lokhande, Pradeep D.
supporting information
p. 2145 - 2149
(2018/05/08)

NITROGEN-CONTAINING BIOPOLYMER-BASED CATALYSTS, THEIR PREPARATION AND USES IN HYDROGENATION PROCESSES, REDUCTIVE DEHALOGENATION AND OXIDATION
The present invention relates to a process for the preparation of a nitrogen containing biopolymer-based catalyst by pyrolysis of a metal complex with a nitrogen-containing biopolymer and to the nitrogen containing biopolymer-based catalysts obtainable by this process. In particular, the invention relates to a nitrogen containing biopolymer-based catalyst comprising metal particles and at least one nitrogen containing carbon layer. The invention also relates to the use of a nitrogen containing biopolymer-based catalyst in a hydrogenation process, preferably in a process for hydrogenation of nitroarenes, nitriles or imines; in a reductive dehalogenation process of C-X bonds, wherein X is CI, Br or I, preferably in a process for dehalogenation of organohalides or in a process for deuterium labelling of arenes via dehalogenation of organohalides; or in an oxidation process. Further, the invention relates to a metal complex with the nitrogen containing biopolymer, wherein the metal is a transition metal selected from the group consisting of manganese, ruthenium, cobalt, rhodium, nickel, palladium and platinum, preferably cobalt or nickel, and wherein the nitrogen containing biopolymer is selected from chitosan, chitin and a polyamino acid, preferably chitosan or chitin.
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Page/Page column 19

(2018/07/29)

Cascade double isocyanide insertion and C-N coupling of 2-iodo-2′-isocyano-1,1′-biphenyls
A palladium-catalyzed double isocyanide insertion using 2-iodo-2′-isocyano-1,1′-biphenyls followed by copper-catalyzed intramolecular C-N coupling, delivering a unique heterocyclic structure containing both phenanthridine and carbazole scaffolds, has been developed. In this cascade process, four chemical bonds, including two C-C, one C-O, and one C-N bonds are formed consecutively without isolating an intermediate. The strategy of using a functionalized isocyanide in double insertion provides a quick approach for constructing heterocyclic systems with high bond-forming efficiency.
Sun, Hongwei,Tang, Shi,Li, Dengke,Zhou, Yali,Huang, Jinbo,Zhu, Qiang
p. 3893 - 3896
(2018/06/07)

Carbazole compound, and synthesis method and application of compound
The invention discloses a carbazole compound represented by a formula (2) and a synthesis method of the compound. A high-iodine salt is taken as a reaction raw material, and under the action of an inorganic nitrogen reagent, an additive, a base and a metal catalyst, a reaction is carried out in a solvent under a condition of 80-150 DEG C to obtain various carbazole compounds. According to the method provided by the invention, nitrogen atoms are introduced in a later period, so that the non-compatibility of nitrogen heterocyclic rings to the reaction conditions such as the metal catalyst and the like in an early reaction period is avoided. In addition, two aryl groups in the high-iodine salt are fully utilized, so that the atomic economic efficiency of the method provided by the present invention is fully exhibited. The carbazole compound prepared by the method provided by the invention can be further applied to the synthesis of non-steroidal anti-inflammatory drug carprofen.
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Paragraph 0038-0041

(2018/06/15)

METHODS AND COMPOSITIONS FOR THE TREATMENT OF RNA VIRAL INFECTIONS
Disclosed herein, inter alia, are agents having antiviral activity and methods of use thereof.
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Paragraph 0612

(2018/05/15)