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Re(VII) complex of N-fused tetraphenylporphyrin
By treatment of N-fused tetraphenylporphyrin rhenium(I) tricarbonyl complex with trimethylamine N-oxide, oxidation of the metal center proceeded to afford N-fused tetraphenylporphyrin rhenium(VII) trioxo complex, which was quite stable against air, light and heat. The Royal Society of Chemistry 2005.
Toganoh, Motoki,Ikeda, Shinya,Furuta, Hiroyuki
p. 4589 - 4591
(2005)
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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)

Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
supporting information
p. 2876 - 2894
(2021/02/01)

Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
p. 1237 - 1242
(2021/06/01)

Palladium nanoparticles encapsulated in polyimide nanofibers: An efficient and recyclable catalyst for coupling reaction
In this study, palladium-encapsulated poly(amic acid) (Pd@PAA) nanofibers were prepared by electrospinning, followed by thermal imidization to synthesize palladium-encapsulated polyimide (Pd@PI) nanofibers. Scanning electron microscopy (SEM) images confirmed the preparation of uniform and smooth Pd@PAA and Pd@PI nanofibers. Thermogravimetric analysis (TGA) results reveal that the Pd@PI nanofibers possessed excellent thermal stability. The dispersion of palladium nanoparticles in the polyimide nanofibers was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The catalysis results show that this Pd@PI fibrous catalyst was very efficient to catalyze the cross-coupling reactions of aromatic iodides with n-butyl acrylate (Heck reaction) or phenylboronic acid derivatives (Suzuki reaction) to afford the desired products in good to excellent yields. Moreover, the Pd@PI catalyst could be easily separated and recovered from the reaction mixture by simple filtration due to the regular fibrous structure and reused for 10 times for both Heck and Suzuki reactions without obvious loss of its initial catalytic activity. Thus, the Pd@PI nanofiber catalyst holds great potential in chemical industry in terms of its excellent catalytic activity and stability.
Du, Yijun,Gou, Faliang,Gao, Danning,Liu, Zhifeng,Shao, Linjun,Qi, Chenze
(2021/09/15)

Efficient and Economical Preparation of Hypercrosslinked Polymers-palladium Based on Schiff Base as Recyclable Catalyst for Suzuki-Miyaura Reactions
A novel hypercrosslinked polymer (HCP) was prepared via Friedel-Crafts alkylation reaction of Schiff base with benzene and formaldehyde dimethyl acetal (FDA) promoted by FeCl3. The HCP was then metalated with Pd(II) to form heterogeneous catalyst. The protocol featured low cost, mild conditions, readily available materials, easy separation and high yield. Physicochemical methods, including IR, N2 sorption, ICP, TGA, XPS, SEM, EDX, and TEM, were used to characterize the catalyst structure and composition. The results reveal that the heterogeneous catalyst possesses high specific surface area, large pore volume, good chemical and thermal stability, and highly dispersed palladium. The heterogeneous catalysts were applied in Suzuki-Miyaura coupling reaction to evaluate their catalytic performance. The experiments reflected that the HCPs-Pd(OAc)2 was an efficient catalyst for Suzuki-Miyaura reactions with the yield of biaryl up to 99%, while the TON could reach 2250. The reusability test showed the catalyst was easily recovered and reused for at least six times without obvious decrease in activity.
Gao, Xiyue,Lin, Hongwei,Liu, Shasha,Luo, Qionglin,Ouyang, Yuejun,Xiang, Bailin,Xiang, Dexuan,Yao, Huan,Zhang, Li
supporting information
p. 1879 - 1882
(2021/10/29)

Immobilization of a Pd(ii)-containing N-heterocyclic carbene ligand on porous organic polymers: efficient and recyclable catalysts for Suzuki-Miyaura reactions
Palladium coordinated with N-heterocyclic carbene-functionalized porous organic polymers (Pd@POPs) was successfully preparedviaScholl coupling reaction and a successive immobilization method. The protocol features simple reaction conditions, easy separation, high yield and low cost. The structure and composition of Pd@POPs were characterized by N2sorption, TGA, FT-IR, SEM, EDX, TEM, XPS and ICP. Then the obtained heterogeneous catalysts were applied in Suzuki-Miyaura coupling reaction to evaluate their catalytic performance. The Pd@POPs displayed high catalytic activity for the Suzuki-Miyaura coupling reaction in an EtOH/H2O solvent. A 0.03 mol% Pd loading was sufficient for the reaction with a high turnover number (TON) of 3220. Moreover, the catalyst was easily recovered and reused for at least six consecutive cycles without obvious loss of its initial activity.
Gao, Xiyue,Lin, Hongwei,Liu, Cijie,Luo, Qionglin,Ouyang, Yuejun,Xiang, Bailin,Xiang, Dexuan,Yao, Huan,Zhou, Nonglin
p. 3676 - 3680
(2021/06/17)

Polydopamine-Encapsulated Dendritic Organosilica Nanoparticles as Amphiphilic Platforms for Highly Efficient Heterogeneous Catalysis in Water
Aqueous heterogeneous catalysis is a green, sustainable catalytic process that attracts increasing attention, but it often suffers from poor mass transfer, substrate adsorption and catalyst dispersion. Herein, we synthesized a type of amphiphilic core-shell catalysts with a hydrophilic polydopamine (PDA) shell and a hydrophobic dendritic organosilica nanoparticle (DON) core for heterogeneous catalysis in water. The hydrophilic shell allowed the catalyst dispersing well in water, and the hydrophobic core facilitated the absorption of organic reactants. The hierarchical core-shell structure facilitated rational arrangement of the location of catalytic species to match the reaction sequence. The obtained metal, enzyme and metal-enzyme amphiphilic catalysts demonstrated improved stability, selectivity and activity in aqueous reactions, including Pd-catalyzed cross-couplings (Suzuki, Liebeskind-Srogl, Heck and Sonogashira), enzymatic enantioselective reduction, chemoenzymatic cascade synthesis of chiral compounds and chemoenzymatic cascade degradation of organophosphates. The amphiphilic catalysts could be easily in situ recovered, and their high catalytic performance was sustained for five cycles.
Gao, Jing,Guo, Na,Jiang, Yanjun,Liu, Guanhua,Liu, Pengbo,Liu, Yunting,Wang, Zihan,Zhang, Lei
supporting information
p. 1975 - 1982
(2021/06/09)

Ligand-to-metal charge transfer of a pyridine surface complex on TiO2for selective dehydrogenative cross-coupling with benzene
Dehydrogenative cross-coupling (DCC) between pyridine and benzene proceeded selectively using a TiO2 photocatalyst under visible light irradiation at optimized concentrations of the substrates. Visible light induces ligand-to-metal charge transfer (LMCT) between pyridine and a TiO2 surface to give a pyridine radical cation, which produces a pyridyl radical by its deprotonation or oxidation of another pyridine molecule. The pyridyl radical attacks a benzene ring to form an sp2C-sp2C bond and a hydrogen atom is subsequently removed to complete DCC. Selective excitation of the pyridine LMCT complex in the presence of an excess amount of benzene would be the key for higher selectivity. This journal is
Hishitani, Shinichiro,Naniwa, Shimpei,Yamamoto, Akira,Yoshida, Hisao
p. 11366 - 11373
(2021/05/31)

Molecular engineered palladium single atom catalysts with an M-C1N3subunit for Suzuki coupling
Single atom catalysis has emerged as a powerful technique for catalysis due to its outstanding performance and atom economy. Controlling the hybridization of the atom with its environment is crucial in determining the selectivity and/or yield of the reaction. However, the single atom environment is usually ill-defined and hard to predict because the pyrolysis process used in preparing SACs damages the original status of the precursors in the catalyst preparation. A molecular engineering approach to synthesize single atom catalysts (SACs) on a heterogeneous template provides a strategy to make SACs with a highly uniform coordinating environment. Herein, we report the preparation of a molecular engineered Pd single atom catalyst with a pre-defined M-N3C1 coordination (Pd-N3C1-SAC) using a structure-rigid Pd-N3C1 porphyrin as the precursor, which shows more efficient Suzuki coupling compared with the SAC with Pd-N4 coordination. The origin of the high activity of the Pd-N3C1-SAC is revealed through density functional theory calculations, where a lower reaction barrier for the rate-determining oxidative addition is identified. This journal is
Liu, Jia,Chen, Zhongxin,Liu, Cuibo,Zhang, Bao,Du, Yonghua,Liu, Chen-Fei,Ma, Lu,Xi, Shibo,Li, Runlai,Zhao, Xiaoxu,Song, Jingting,Sui, Xin Zhi,Yu, Wei,Miao, Ling,Jiang, Jianjun,Koh, Ming Joo,Loh, Kian Ping
supporting information
p. 11427 - 11432
(2021/05/19)

Nickel-catalyzed heterocyclic phosphonium salt and aryl bromide direct reduction cross-coupling method and product
The invention discloses a nickel-catalyzed heterocyclic phosphonium salt and aryl bromide direct reduction cross-coupling method and a product, and the method comprises the following steps: in a nitrogen atmosphere, heating a mixture of magnesium chips and lithium chloride; cooling the mixture to room temperature, and adding an ultra-dry solvent into the mixture; then respectively adding a phosphonium salt compound, a catalyst, a ligand and aryl bromide, and stirring to react; and quenching, washing, extracting and drying the reaction product, and separating by column chromatography to obtain the arylated pyridine or diazine compound. The preparation method has the characteristics of mild reaction conditions, simple post-treatment, green steps, low pollution, high economic benefits and the like.
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Paragraph 0034-0040; 0055-0077

(2021/09/15)

Inhibition of (dppf)nickel-catalysed Suzuki-Miyaura cross-coupling reactions by α-halo-N-heterocycles
A nickel/dppf catalyst system was found to successfully achieve the Suzuki-Miyaura cross-coupling reactions of 3- and 4-chloropyridine and of 6-chloroquinoline but not of 2-chloropyridine or of other α-halo-N-heterocycles. Further investigations revealed that chloropyridines undergo rapid oxidative addition to [Ni(COD)(dppf)] but that α-halo-N-heterocycles lead to the formation of stable dimeric nickel species that are catalytically inactive in Suzuki-Miyaura cross-coupling reactions. However, the corresponding Kumada-Tamao-Corriu reactions all proceed readily, which is attributed to more rapid transmetalation of Grignard reagents.
Burton, Paul M.,Cooper, Alasdair K.,Donohoe, William,Greaves, Megan E.,Kennedy, Alan R.,Nelson, David J.,Ronson, Thomas O.
p. 14074 - 14082
(2021/11/12)

Catalysis with magnetically retrievable and recyclable nanoparticles layered with Pd(0) for C-C/C-O coupling in water
Nanoparticles layered with palladium(0) were prepared from nano-sized magnetic Fe3O4 by coating it with silica and then reacting sequentially with phenylselenyl chloride under an N2 atmosphere and palladium(ii) chloride in water. The resulting Fe3O4?SiO2?SePh?Pd(0) NPs are magnetically retrievable and the first example of NPs in which the outermost layer of Pd(0) is mainly held by selenium. The weight percentage of Pd in the NPs was found to be 1.96 by ICP-AES. The NPs were authenticated via TEM, SEM-EDX, XPS, and powder XRD and found to be efficient as catalysts for the C-O and C-C (Suzuki-Miyaura) coupling reactions of ArBr/Cl in water. The oxidation state of Pd in the NPs having size distribution from ～12 to 18 nm was inferred as zero by XPS. They can be recycled more than seven times. The main features of the proposed protocols are their mild reaction conditions, simplicity, and efficiency as the catalyst can be separated easily from the reaction mixture by an external magnet and reused for a new reaction cycle. The optimum loading (in mol% of Pd) was found to be 0.1-1.0 and 0.01-1.0 for O-arylation and Suzuki-Miyaura coupling, respectively. For ArCl, the required amount of NPs was more as compared to that needed for ArBr. The nature of catalysis is largely heterogeneous.
Joshi, Hemant,Sharma, Alpesh K.,Singh, Ajai K.
p. 6452 - 6459
(2020/02/25)

Synthesis of Enaminone-Pd(II) Complexes and Their Application in Catalysing Aqueous Suzuki-Miyaura Cross Coupling Reaction
A series of Pd(II)-enaminone complexes, termed Pd(eao)2, have been synthesized and characterized. The investigation on the catalytic activities of these new Pd(II)-reagents has proved that the Pd(eao)2-1 possesses excellent catalytic activity for the Suzuki- Miyaura cross coupling reactions of aryl bromides/chlorides with aryl/vinyl boronic acids in the environmentally benign media of aqueous PEG400 at low loading (5 mol‰). The superiority of this Pd(II)-reagent to those commercial Pd(II) and Pd(0) catalysts in catalyzing the reactions has been confirmed by parallel experiments. What's more, Pd(eao)2-2 has been found as a practical catalyst for the homo-coupling reactions of aryl boronic acids.
Fu, Leiqing,Cao, Xiaoji,Wan, Jie-Ping,Liu, Yunyun
p. 254 - 258
(2020/01/25)

Hybrid organic-inorganic Cu(II) iminoisonicotine@TiO2@Fe3O4 heterostructure as efficient catalyst for cross-couplings
Two novel mononuclear copper (II) complex catalysts were synthesized from a new tridentate iminoisonicotine ligand (HL) by coordination with Cu(II) ion, with (CuL@TiO2@Fe3O4) and without (CuL) immobilization on TiO2-coated nanoparticles of Fe3O4. The ester moiety on the back of the ligand was utilized for immobilization on nanoparticles of Fe3O4. Both ligand and CuL complex were fully characterized by using?alternative spectral techniques (nuclear magnetic resonance, infrared, ultraviolet-visible and mass spectroscopy, and elemental analyses). Different analytical techniques were used to identify the structural feature and morphology of the immobilized copper catalyst (CuL@TiO2@Fe3O4) shell-shell-core system. The structural analysis revealed that the catalyst system is composed of both agglomerated nanospheres and deformed nanorods. Both copper catalysts, immobilized CuL@TiO2@Fe3O4 and un-immobilized CuL were studied in heterogeneous and homogeneous catalysis, respectively, for Suzuki-Miyaura (C–C) and Buchwald-Hartwig (C–N) cross-coupling reactions of various heteroaryl halides. Both catalysts showed good catalytic potential under the controlled optimal reaction conditions. In contrast to the homogeneous catalyst (CuL), the heterogeneous catalyst (CuL@TiO2@Fe3O4) showed slightly better catalytic performance. The characteristic obtains supported the catalytic potential of the current samples. Reusability/recycling of both catalysts was also investigated in C–C cross-coupling reactions. It was found that the homogeneous catalyst (CuL) could be only recycled up to three times, whereas the heterogeneous one (CuL@TiO2@Fe3O4) could be reused up to seven times with good efficiency.
Adam, Mohamed Shaker S.,Ullah, Farman,Makhlouf, Mohamed M.
p. 4632 - 4653
(2020/03/30)

Catalytic Deoxygenation of Amine and Pyridine N-Oxides Using Rhodium PCcarbeneP Pincer Complexes
Rhodium PCcarbeneP pincer complexes 1-L (L = PPh3, PPh2(C6F5), PCy3) readily facilitate deoxygenation of amine and pyridine N-oxides. The resulting complexes exhibit δ2-C= O coordination of the resulting keto POP pincer ligand. These δ2-Ca? O linkages in the metalloepoxide complexes are readily reduced by isopropyl alcohol and various benzylic alcohols. Thus, efficient catalytic deoxygenation of amine and pyridine N-oxides is possible using complexes 1-L and isopropyl alcohol. This represents a pioneering example of PCcarbeneP pincer complexes being used as catalysts for catalytic deoxygenation.
Tinnermann, Hendrik,Sung, Simon,Cala, Beatrice A.,Gill, Hashir J.,Young, Rowan D.
p. 797 - 803
(2020/03/13)

On the Virtue of Indium in Reduction Reactions. A Comparison of Reductions Mediated by Indium and Zinc: Is Indium Metal an Effective Catalyst for Zinc Induced Reductions?
Indium(0)-mediated reductions have been reported for the transformation of several functional groups (imines, oximes, nitro groups, isoxazolidines, and conjugated alkenes, among others), prompted by the opportunity of performing the reactions in aqueous media and green conditions. We describe here the comparison of several reactions using indium or the less expensive zinc, carried out in order to evaluate the effective advantages brought about indium metal. We found some reactions for which use of In is mandatory and others where Zn worked equally well or even better. The reduction of hydroxylamines to the corresponding amines was the only reduction for which use of In provided much better results than Zn and was also possible to apply an efficient catalytic version with use of 2–5 mol-% In in the presence of stoichiometric Zn. Applicability of this catalytic reduction to “one-pot” model processes is also demonstrated.
Matassini, Camilla,Bonanni, Marco,Marradi, Marco,Cicchi, Stefano,Goti, Andrea
supporting information
p. 1106 - 1113
(2019/12/24)

Catalyst-Free N-Deoxygenation by Photoexcitation of Hantzsch Ester
A mild and operationally simple protocol for the deoxygenation of a variety of heteroaryl N-oxides and nitroarenes has been developed. A mixture of substrate and Hantzsch ester is proposed to result in an electron donor-acceptor complex, which upon blue-light irradiation undergoes photoinduced electron transfer between the two reactants to afford the products. N-oxide deoxygenation is demonstrated with 22 examples of functionally diverse substrates, and the chemoselective reduction of nitroarenes to the corresponding hydroxylamines is also shown.
Cardinale, Luana,Jacobi Von Wangelin, Axel,Konev, Mikhail O.
supporting information

(2020/02/15)

Visible-Light-Driven C4-Selective Alkylation of Pyridinium Derivatives with Alkyl Bromides
Reported herein is a general strategy for the photochemical cross-coupling between N-amidopyridinium salts and various alkyl bromides under photocatalyst-free conditions, granting facile access to various C4-alkylated pyridines. This approach exploits the intriguing photochemical activity of electron donor-acceptor (EDA) complexes between N-amidopyridinium salts and bromide, which provides a photoactive handle capable of generating silyl radicals and driving the alkylation process. The robustness of this protocol was further demonstrated by the late-stage functionalization of complex compounds under mild and metal-free conditions.
Hong, Sungwoo,Jung, Sungwoo,Park, Seongjin,Shin, Sanghoon
supporting information
p. 11370 - 11375
(2020/07/21)

Small organic molecules with tailored structures: Initiators in the transition-metal-free C-H arylation of unactivated arenes
Simple, small organic molecules containing nitrogen and oxygen atoms in their structures have been disclosed to catalyze transition-metal-free C-H arylation of unactivated arenes with aryl iodides in the presence of tBuOK. In this article, an optimized catalytically active molecule, (2-(methylamino)phenyl)methanol, was designed. A broad range of aryl iodides could be converted into the corresponding arylated products at 100 °C over 24 h with good to excellent yields. Mechanistic experiments verified that radicals participated in this catalytic transformation and that the cleavage of the aromatic C-H bond was not the rate determining step. A K+ capture experiment by 18-crown-6 emphasized the significance of the cation species of the strong base. Fourier transform infrared spectroscopy proved that the catalytic system was activated by the hydrogen bonds between small organic molecules and tBuOK. Also, a clear mechanism was proposed. This transition-metal-free method affords a promising system for efficient and inexpensive synthesis of biaryls via a user-friendly approach, as confirmed by scale-up experiments.
Chen, Suqing,Chen, Wenjun,Chen, Yu,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong
p. 14500 - 14509
(2020/04/27)

NCP-Type Pincer Iridium Complexes Catalyzed Transfer-Dehydrogenation of Alkanes and Heterocycles?
A series of NCP-type pincer iridium complexes, (RNCCP)IrHCl (2a—2c) and (BQ-NCOP)IrHCl 3, have been studied for catalytic transfer alkane dehydrogenation. Complex 3 containing a rigid benzoquinoline backbone exhibits high activity and robustness in dehydrogenation of alkanes to form alkenes. Even more importantly, this catalyst system was also highly effective in the dehydrogenation of a wide range of heterocycles to furnish heteroarenes.
Wang, Yulei,Qian, Lu,Huang, Zhidao,Liu, Guixia,Huang, Zheng
supporting information
p. 837 - 841
(2020/05/18)

Iodine-catalyzed convergent aerobic dehydro-aromatization toward benzazoles and benzazines
An iodine-catalyzed aerobic dehydro-aromatization has been developed, providing straightforward and efficient access to various benzoazoles and benzoazines. The present transition-metal-free protocol enables the dehydro-aromatization of tetrahydrobenzazoles and tetrahydroquinolines with molecular oxygen as the green oxidant, along with some other N-heterocycles. Hence, a broad range of heteroaromatic compounds are generated in moderate to good yields under facile reaction conditions.
Chen, Shanping,Deng, Guo-Jun,Jiang, Pingyu,Ni, Penghui,Tuo, Xiaolong,Wang, Xiaodong
p. 8348 - 8351
(2020/03/11)

Palladium Supported on Silk Fibroin for Suzuki–Miyaura Cross-Coupling Reactions
Silk fibroin supported Pd (Pd/SF) has been prepared and used as catalyst in Suzuki–Miyaura cross-coupling reactions in water/ethanol (4:1 v/v) mixture. The reactions proceed rapidly with aryl iodides and boronic acids with different electronic properties using low metal loading (0.38 mol-%). Pd/SF exhibits better recyclability compared to other biopolymer-supported Pd catalysts, up to nineteen cycles without loss of activity.
Albano, Gianluigi,Farinola, Gianluca M.,Lo Presti, Marco,Milella, Antonella,Omenetto, Fiorenzo G.,Rizzo, Giorgio
supporting information
p. 6992 - 6996
(2020/11/30)

Anchoring Positively Charged Pd Single Atoms in Ordered Porous Ceria to Boost Catalytic Activity and Stability in Suzuki Coupling Reactions
Single-atom (SA) catalysis bridging homogeneous and heterogeneous catalysis offers new opportunities for organic synthesis, but developing SA catalysts with high activity and stability is still a great challenge. Herein, a heterogeneous catalyst of Pd SAs anchored in 3D ordered macroporous ceria (Pd-SAs/3DOM-CeO2) is developed through a facile template-assisted pyrolysis method. The high specific surface area of 3DOM CeO2 facilitates the heavily anchoring of Pd SAs, while the introduction of Pd atoms induces the generation of surface oxygen vacancies and prevents the grain growth of CeO2 support. The Pd-SAs/3DOM-CeO2 catalyst exhibits excellent activity toward Suzuki coupling reactions for a broad scope of substrates under ambient conditions, and the Pd SAs can be stabilized in CeO2 in long-term catalytic cycles without leaching or aggregating. Theoretical calculations indicate that the CeO2 supported Pd SAs can remarkably reduce the energy barriers of both transmetalation and reductive elimination steps for Suzuki coupling reactions. The strong metal-support interaction contributes to modulating the electronic state and maintaining the stability of Pd SA sites. This work demonstrates an effective strategy to design and synthesize stable single-atom catalysts as well as sheds new light on the origin for enhanced catalysis based on the strong metal-support interactions.
Tao, Xueqin,Long, Ran,Wu, Di,Hu, Yangguang,Qiu, Ganhua,Qi, Zeming,Li, Benxia,Jiang, Ruibin,Xiong, Yujie
(2020/10/09)

Pillar[5]arene-Based [2]Rotaxane: Synthesis, Characterization, and Application in a Coupling Reaction
Mechanically interlocked molecules are a class of smart supramolecular species because of their interesting topological structure and application in various areas, such as biology and nanoscience. In this work, we used "multicomponent reaction"to fabricate a new [2]rotaxane based on pillar[5]arene from different small-sized molecules. The molecular structure of the obtained [2]rotaxane R was confirmed by 1H and 13C NMR, high-resolution electrospray ionization mass spectrometry, two-dimensional nuclear Overhauser effect spectroscopy, and density functional theory studies. Interestingly, the [2]rotaxane-based organometallic cross-linked catalyst (Pd?R) was easily constructed via the coordination between triazole groups and Pd(NO3)2. Pd?R proved to be a good catalyst for the Suzuki-Miyaura coupling reaction with excellent stability and repeatability.
Ding, Yue,Guo, Hao,Ou, Changjin,Wang, Jin,Wang, Yang,Yan, Chaoguo,Yao, Yong,Ye, Junmei,Yuan, Xiaolei,Zhang, Zhecheng
supporting information
p. 11915 - 11919
(2020/09/15)

[2]rotaxane based on pillararene as well as preparation and application thereof
The invention provides [2]rotaxane based on pillararene as well as preparation and application thereof in catalytic coupling reaction, and belongs to the technical field of organic synthesis. According to the present invention, by using the host-guest complexation between the pillararene and a neutral guest, the novel [2]rotaxane based on the pillararene is successfully and efficiently constructed, a novel catalyst is further prepared through the coordination of the [2]rotaxane based on the pillararene and Pd, and the catalyst has good catalysis efficiency and can be recycled.
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Paragraph 0041-0046

(2020/10/14)

Suzuki-Miyaura Cross-Coupling of Sulfoxides
The utilization of diphenyl sulfoxides as versatile electrophilic coupling partners for the Suzuki-Miyaura reaction via C-S bond cleavage was successfully developed under palladium-N-heterocyclic carbene catalysis. The reactions showed good functional group compatibility, proceeded well under mild conditions, and provided biaryls in yields of up to 96%. A wide range of useful functional groups, such as fluoro, chloro, ether, hydroxyl, amide, cyano, keto, trimethylsilyl (TMS), and ester were tolerated under the reaction conditions; however, the use of phenylboronic anhydride and arylboronic acid pinacol esters generally would lead low yields. Good regioselectivity for the electron-poor phenyl group was achieved when unsymmetrical diphenyl sulfoxides were used. The protocol is applicable at the gram scale even with half the amount of catalyst. Density functional theory calculations were performed to investigate the reaction mechanism, indicating that the reaction occurred through oxidative addition, transmetalation, and reductive elimination to provide the final coupling product.
Abduhulam, Hayrul,Cao, Changsheng,Chen, Qianwei,Dang, Yanfeng,Li, Chengxi,Shi, Yanhui,Wu, Shufeng,Yan, Shuqin
p. 8168 - 8176
(2020/09/18)

Photorelease of Pyridines Using a Metal-Free Photoremovable Protecting Group
The photorelease of bioactive molecules has emerged as a valuable tool in biochemistry. Nevertheless, many important bioactive molecules, such as pyridine derivatives, cannot benefit from currently available organic photoremovable protecting groups (PPGs). We found that the inefficient photorelease of pyridines is attributed to intramolecular photoinduced electron transfer (PET) from PPGs to pyridinium ions. To alleviate PET, we rationally designed a strategy to drive the excited state of PPG from S1 to T1 with a heavy atom, and synthesized a new PPG by substitution of the H atom at the 3-position of 7-dietheylamino-coumarin-4-methyl (DEACM) with Br or I. This resulted in an improved photolytic efficiency of the pyridinium ion by hundreds-fold in aqueous solution. The PPG can be applied to various pyridine derivatives. The successful photorelease of a microtubule inhibitor, indibulin, in living cells was demonstrated for the potential application of this strategy in biochemical research.
Dong, Zaizai,Fang, Xiaohong,Kou, Xiaolong,Tan, Weihong,Tang, Xiao-Jun,Wu, Yayun,Zhang, Zhen,Zhao, Rong,Zhou, Wei
supporting information
p. 18386 - 18389
(2020/08/24)

Visible-Light Photoredox-Catalyzed Formal [5 + 1] Cycloaddition of N-Tosyl Vinylaziridines with Difluoroalkyl Halides
A visible-light photoredox-catalyzed formal [5 + 1] cycloaddition of N-tosyl vinylaziridines with difluoroalkyl halides as unique C1 synthons was developed. The procedure provides an efficient and practical method to synthesize diverse pyridines in moderate to good yields. The reaction underwent a radical-initiated kinetically controlled ring-opening of vinylaziridines and involved a key α,β-unsaturated imine intermediate, followed by an E2 elimination, a 6πelectrocyclization, and defluorinated aromatization.
Liu, Yantao,Luo, Wen,Wang, Zhenjie,Zhao, Yuxin,Zhao, Jingjing,Xu, Xuejun,Wang, Chaojie,Li, Pan
supporting information
p. 9658 - 9664
(2020/12/21)

A Supramolecular Palladium Catalyst Displaying Substrate Selectivity by Remote Control
Inspired by enzymes such as cytochrome P-450, the study of the reactivity of metalloporphyrins continues to attract major interest in the field of homogeneous catalysis. However, little is known about benefitting from the substrate-recognition properties of porphyrins containing additional, catalytically relevant active sites. Herein, such an approach is introduced by using supramolecular ligands derived from metalloporphyrins customized with rigid, palladium-coordinating nitrile groups. According to different studies (NMR and UV/Vis spectroscopy, XRD, control experiments), the supramolecular ligands are able to accommodate pyridine derivatives as substrates inside the porphyrin pocket while the reactivity occurs at the peripheral side. By simply tuning a remote metal center, different binding events result in different catalyst reactivity, and this enzyme-like feature leads to high degrees of substrate selectivity in representative palladium-catalyzed Suzuki–Miyaura reactions.
Zardi, Paolo,Roisnel, Thierry,Gramage-Doria, Rafael
supporting information
p. 627 - 634
(2019/01/04)

Heterogeneous Catalytic Reduction of Tertiary Amides with Hydrosilanes Using Unsupported Nanoporous Gold Catalyst
We have demonstrated that the unsupported nanoporous gold (AuNPore) was a green and highly efficient heterogeneous catalyst for the reduction of amides to amines using hydrosilanes as reductants. A variety of tertiary amides with a broad functional groups were reduced to the corresponding tertiary amines in the presence of 2 mol% of AuNPore and PheMe2SiH or (Me2SiH)2O under mild conditions. AuNPore catalyst was recovered by simple filtration and used for twelve times without any loss of catalytic activity. The AuNPore/hydrosilane system was also successfully applied to the hydrosilative reduction of sulfoxides and N-oxides. (Figure presented.).
Zhao, Yuhui,Zhang, Sheng,Yamamoto, Yoshinori,Bao, Ming,Jin, Tienan,Terada, Masahiro
supporting information
p. 4817 - 4824
(2019/10/28)

Electrochemical Deoxygenation of N-Heteroaromatic N -Oxides
An electrochemical method for the deoxygenation of N-heteroaromatic N -oxide to give the corresponding N-heteroaromatics has been developed. Several classes of N-heterocycles such as pyridine, quinoline, isoquinoline, and phenanthridine are tolerated. The electrochemical reactions proceed efficiently in aqueous solution without the need for transition-metal catalysts and waste-generating reducing reagents.
Xu, H.-C.,Xu, P.
supporting information
p. 1219 - 1221
(2019/06/08)

Photoarylation of Pyridines Using Aryldiazonium Salts and Visible Light: An EDA Approach
A metal-free methodology for the photoarylation of pyridines, in water, is described giving 2 and 4-arylated-pyridines in yields up to 96percent. The scope of the aryldiazonium salts is presented showing important results depending on the nature and position of the substituent group in the diazonium salt, that is, electron-donating or electron-withdrawing in the ortho, meta, or para positions. Further heteroaromatics were also successfully photoarylated. Mechanistic studies and comparison between our methodology and similar metal-catalyzed procedures are presented, suggesting the occurrence of a visible-light EDA complex which generates the aryl radical with no need for an additional photocatalyst.
Bartolomeu, Aloisio De A.,Brocksom, Timothy J.,De Oliveira, Kleber T.,No?l, Timothy,Silva, Rodrigo C.
(2019/08/26)

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)

Involving Single-Atom Silver(0) in Selective Dehalogenation by AgF under Visible-Light Irradiation
The dehalogenation-arylation and the hydrodehalogenation of various types of organic halides are selectively realized using AgF and visible light without any organic additives under mild conditions. Single-atom silver(0) (denoted as SAAg) serves as the catalytically active center, and the TOF of SAAg reaches 6000 h-1. This elusive activity of Ag is beyond that expected from its ionic, nano, or bulk forms.
Wu, Wenli,Cui, Enxin,Zhang, Yun,Zhang, Chen,Zhu, Feng,Tung, Chen-Ho,Wang, Yifeng
p. 6335 - 6341
(2019/07/04)

The one-pot synthesis of pyridine derivatives from the corresponding 1,5-dicarbonyl compounds
The optimization of the one-pot, acid-promoted synthesis of pyridine and alkylpyridine derivatives from simple alkyl-1,5-dicarbonyl derivatives and via the corresponding oxime intermediate is described. Of all the combinations of and solvents tested, the use of HCl in refluxing dioxane was found to result in the highest chemical yields. Twelve pyridines were prepared using this method.
Mihara, Hiromichi,Miyakoshi, Takeru,Kikuchi, Yui,Konno, Hiroyuki
p. 1375 - 1383
(2019/12/23)

Synthesis, characterization and catalytic performance of palladium supported on pyridine-based covalent organic polymer for Suzuki-Miyaura reaction
A bipyridine-based covalent organic polymer (COP) was successfully synthesized by condensation of trimesoyl chloride (TMC) and 2,2′-bipyridine-5,5′-diamine (Bpy) under ambient conditions. This material was modified by coordination of PdCl2 to COP framework, affording a hybrid material, Pd@TMC-Bpy COP, which was applied as a highly efficient heterogeneous catalyst for Suzuki-Miyaura reaction under ligand-free conditions in ethyl lactate. The catalyst could be reused for five times without obvious loss of its activity.
Han, Yi,Di, Jia-Qi,Zhao, Ai-Dong,Zhang, Zhan-Hui
(2019/08/22)

Transition-Metal-Free Desulfinative Cross-Coupling of Heteroaryl Sulfinates with Grignard Reagents
A mild cross-coupling reaction of heteroaryl sulfinates with Grignard reagents has been developed under transition-metal-free conditions. This study provides an example of the SO22- as a leaving group in an aromatic system and an effective methodology for the construction of C-C bond.
Wei, Jun,Liang, Huamin,Ni, Chuanfa,Sheng, Rong,Hu, Jinbo
supporting information

(2019/02/05)

Scope and limitation of propylene carbonate as a sustainable solvent in the Suzuki-Miyaura reaction
The Suzuki-Miyaura reaction is one of the most used transformations in drug research. Thus making this reaction more sustainable is of considerable current interest. Here we show that propylene carbonate (PC) can be used as a solvent for the Suzuki-Miyaura reaction. PC is one of the greenest solvents since it is synthesized under green conditions by the use of carbon dioxide in the air. All reactions proceeded well and good or excellent yields were observed for the biaryl products. Nonetheless in the case of pyridazinones, 2-hydroxypropyl- chain containing side-products were observed. Importantly, this fact allowed the isolation of several novel compounds which were generated under prominently green conditions.
Czompa, Andrea,Pásztor, Balázs László,Sahar, Jennifer Alizadeh,Mucsi, Zoltán,Bogdán, Dóra,Ludányi, Krisztina,Varga, Zoltán,Mándity, István M.
p. 37818 - 37824
(2019/12/03)

Preparation and Reactivation of Heterogeneous Palladium Catalysts and Applications in Sonogashira, Suzuki, and Heck Reactions in Aqueous Media
A new type of heterogeneous palladium catalyst, PdMgAl-LDH, was facilely prepared by the immobilization of Pd2+ species in the layers of a Mg-Al layered double hydroxide (LDH) with co-precipitation, and then fully characterized by using powder XRD, thermogravimetric differential thermal analysis, TEM, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques. These catalysts can efficiently catalyze copper-free Sonogashira, Suzuki and Heck coupling reactions of various aryl iodides, bromides, and chlorides in aqueous media under phosphine-ligand- and organic-base-free conditions. These catalysts feature easy recovery through simple filtration and could be reused at least six times without a marked loss in activity. Notably, they can be facilely reactivated by a combination of nitrolysis with co-precipitation. The basic LDH skeletons could effectively stabilize the Pd0 species created in situ and donate electron density to the Pd0 center to facilitate the oxidative addition of aryl halides, thus the PdMgAl-LDH catalysts are stable during catalysis.
Zhang, Sheng-Yan,Yu, Kai,Guo, Yu-Shuang,Mou, Rui-Qi,Lu, Xiao-Fan,Guo, Dian-Shun
p. 803 - 813
(2018/10/31)

Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic N-Oxides
A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
Kim, Kyu Dong,Lee, Jun Hee
supporting information
p. 7712 - 7716
(2019/01/03)

Mild Deoxygenation of Sulfoxides over Plasmonic Molybdenum Oxide Hybrid with Dramatic Activity Enhancement under Visible Light
Harvesting solar light to boost commercially important organic synthesis still remains a challenge. Coupling of conventional noble metal catalysts with plasmonic oxide materials which exhibit intense plasmon absorption in the visible light region is a promising option for efficient solar energy utilization in catalysis. Herein, we for the first time demonstrate that plasmonic hydrogen molybdenum bronze coupled with Pt nanoparticles (Pt/HxMoO3-y) shows a high catalytic performance in the deoxygenation of sulfoxides with 1 atm of H2 at room temperature, with dramatic activity enhancement under visible light irradiation relative to dark conditions. The plasmonic molybdenum oxide hybrids with strong plasmon resonance peaks pinning at around 556 nm are obtained via a facile H-spillover process. Pt/HxMoO3-y hybrid provides excellent selectivity for the deoxygenation of various sulfoxides as well as pyridine N-oxides, in which drastically improved catalytic efficiencies are obtained under the irradiation of visible light. Comprehensive analyses reveal that oxygen vacancies massively introduced via a H-spillover process are the main active sites, and the reversible redox property of Mo atoms and strong plasmonic absorption play key roles in this reaction. The catalytic system works under extremely mild conditions and can boost the reaction by the assistance of visible light, offering an ultimately greener protocol to produce sulfides from sulfoxides. Our findings may open up a new strategy for designing plasmon-based catalytic systems that can harness visible light efficiently.
Kuwahara, Yasutaka,Yoshimura, Yukihiro,Haematsu, Kohei,Yamashita, Hiromi
p. 9203 - 9210
(2018/06/25)

Accessing Heterobiaryls through Transition-Metal-Free C-H Functionalization
Herein we report a transition-metal-free synthetic protocol for heterobiaryls, one of the most important pharmacophores in the modern drug industry, employing a new multidonor phenalenyl (PLY)-based ligand. The current procedure offers a wide substrate scope (24 examples) with a low catalyst loading resulting in an excellent product yield (up to 95%). The reaction mechanism involves a single electron transfer (SET) from a phenalenyl-based radical to generate a reactive heteroaryl radical. To establish the mechanism, we have isolated the catalytically active SET initiator, characterizing by a magnetic study.
Banik, Ananya,Paira, Rupankar,Shaw, Bikash Kumar,Vijaykumar, Gonela,Mandal, Swadhin K.
p. 3236 - 3244
(2018/03/23)

[2,2′-bipyridin]-6(1 H)-one, a Truly Cooperating Ligand in the Palladium-Mediated C-H Activation Step: Experimental Evidence in the Direct C-3 Arylation of Pyridine
The ligand [2,2′-bipyridin]-6(1H)-one (bipy-6-OH) has a strong accelerating effect on the Pd-catalyzed direct arylation of pyridine or arenes. The isolation of relevant intermediates and the study of their decomposition unequivocally show that the deprotonated coordinated ligand acts as a base and assists the cleavage of the C-H bond. Mechanistic work indicates that the direct arylation of pyridine with this ligand occurs through a Pd(0)/Pd(II) cycle. Because of this dual ligand-intramolecular base role, there is no need for an available coordination site on the metal for an external base, a difficulty encountered when chelating ligands are used in coupling reactions that involve a C-H cleavage step.
Salamanca, Vanesa,Toledo, Alberto,Albéniz, Ana C.
supporting information
p. 17851 - 17856
(2019/01/04)

Urea-based organocatalyst catalyzed direct C–H bond arylations of unactivated arenes
A simple 1,3-diethylurea was demonstrated to catalyze transition-metal-free arylations of unactivated aromatic C–H bonds with aryl iodides in the presence of t-BuOK. A broad range of aryl iodides with different arenes could couple in moderate to excellent yields. The mechanistic experiment results indicated that the radical is involved in this transformation.
Zhao, Huaiqing,Xu, Xiangwen,Wu, Wei,Zhang, Wei,Zhang, Yunxian
p. 95 - 99
(2018/04/24)

Synthesis method of biaryl compounds
The invention discloses a synthesis method of biaryl compounds. The method comprises the following step: enabling iodoaromatic compounds to react with aromatic hydrocarbon compounds in the presence ofa urea derivative catalyst and additives so as to obtain the biaryl compounds. According to the synthesis method of the biaryl compounds, all the steps are carried out in one reactor, and a separation step is not needed during synthesis, so that the reaction belongs to a one-pot reaction, the reaction yield is increased, and the reaction product is easy to purify. The synthesis method provided bythe invention uses a series of urea derivatives as the catalyst, and a single electron transfer process occurs between the catalyst and reactants so as to form free radicals, so that a C-C bond is further catalyzed to be formed, and biaryl is produced. Compared with the traditional transition metal catalysis method, the catalyst is cheap and easy to obtain, has good selectivity, high yield and strong applicability, and is easy to treat after the reaction is finished, so that the cost is lowered and the synthesis rate is increased.
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Paragraph 0112-0116

(2020/12/30)

Monoamine Oxidase (MAO-N) Whole Cell Biocatalyzed Aromatization of 1,2,5,6-Tetrahydropyridines into Pyridines
A sustainable MAO-N biocatalyzed process for the synthesis of pyridines from aliphatic tetrahydropyridines (THP) has been developed. Pyridine compounds were synthesized under mild reaction conditions and with high conversion, exploiting MAO-N whole cells as aromatizing biocatalysts. The kinetic profile of the whole cell biocatalytic transformation was finally investigated via in situ 19F NMR.
Toscani, Anita,Risi, Caterina,Black, Gary W.,Brown, Nicola L.,Shaaban, Ali,Turner, Nicholas J.,Castagnolo, Daniele
p. 8781 - 8787
(2018/09/06)

Room temperature dehalogenation of (hetero)aryl halides with magnesium/methanol
Magnesium in methanol was found to be an effective and inexpensive reagent for the dehalogenation of (hetero)aryl chlorides, bromides and iodides under mild conditions. The halogen/hydrogen exchange proceeded at room temperature and tolerated functional groups such as esters, nitriles, alcohols, and alkenes.
Jouha, Jabrane,Khouili, Mostafa,Hiebel, Marie-Aude,Guillaumet, Gérald,Suzenet, Franck
supporting information
p. 3108 - 3111
(2018/07/13)

Visible Light-Mediated Decarboxylative Alkylation of Pharmaceutically Relevant Heterocycles
A net redox-neutral method for the decarboxylative alkylation of heteroarenes using photoredox catalysis is reported. Additionally, this method features the use of simple, commercially available carboxylic acid derivatives as alkylating agents, enabling the facile alkylation of a variety of biologically relevant heterocyclic scaffolds under mild conditions.
Sun, Alexandra C.,McClain, Edward J.,Beatty, Joel W.,Stephenson, Corey R. J.
supporting information
p. 3487 - 3490
(2018/06/26)

Super electron donors derived from diboron
Single-electron transfer is an important process in organic chemistry, in which a single-electron reductant (electron donor) acts as a key component. Compared with metal-based electron donors, organic electron donors have some unique advantages, such as tunable reduction ability and mild reaction conditions. The development of novel organic electron donors with good reduction ability together with ease of preparation is in high demand. Based on the pyridine-catalyzed radical borylation reaction developed in our laboratory, we have discovered that, the reaction system consisting of a diboron(4) compound, methoxide and a pyridine derivative could smoothly produce super electron donors in situ. Two boryl-pyridine based species, the major one being a trans-2H,2′H-[2,2′-bipyridine]-1,1′-diide borate complex and the minor one being a pyridine radical anion-borate complex, were observed and carefully characterized. These complexes were found to be organic super electron donors unprecedented in literature, and their formation mechanisms were studied by DFT calculations. The diboron/methoxide/pyridine system enables the preparation of organic super electron donors from easily accessible starting materials under mild conditions, which has the potential to be a general and practical single-electron reducing agent in organic synthesis.
Zhang, Li,Jiao, Lei
p. 2711 - 2722
(2018/03/21)

Synthesis of Bi(hetero)aryls via Sequential Oxidation and Decarboxylation of Benzylamines in a Batch/Fully Automated Continuous Flow Process
Catalytic dehydrogenative cross-coupling of two C–H bonds represents a green strategy in view of the atom- and step-economy. However, the challenge is to discover a new innovative bond strategy, especially for the direct coupling between Csp2–H
Mahajan, Bhushan,Aand, Dnyaneshwar,Singh, Ajay K.
supporting information
p. 2831 - 2835
(2018/06/21)