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Product inhibition in nucleophilic aromatic substitution through DPPPent-supported π-arene catalysis
Nucleophilic aromatic substitution (SNAr) of fluorobenzene by morpholine at a bis(diphenylphosphino)pentane-supported ruthenim complex is investigated as a model system for π-arene catalysis through the synthesis and full characterization of proposed intermediates. The SNAr step proceeds quickly at room temperature, however the product N-phenylmorpholine binds tightly to the ruthenium ion. In the case examined, the thermodynamics of arene binding favor product N-phenylmorpholine over fluorobenzene binding by a factor of 2000, corresponding to significant product inhibition. Observations of the catalyst resting state support this hypothesis and demonstrate an additive-controlled role for a previously-proposed ligand cyclometalation. This journal is
Mueller, Benjamin R. J.,Schley, Nathan D.
p. 10114 - 10119
(2020)
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Organic chemistry: Pharmaceutical diversification via palladium oxidative addition complexes
Palladium-catalyzed cross-coupling reactions have transformed the exploration of chemical space in the search for materials, medicines, chemical probes, and other functional molecules. However, cross-coupling of densely functionalized substrates remains a major challenge.We devised an alternative approach using stoichiometric quantities of palladium oxidative addition complexes (OACs) derived from drugs or drug-like aryl halides as substrates. In most cases, cross-coupling reactions using OACs proceed under milder conditions and with higher success than the analogous catalytic reactions. OACs exhibit remarkable stability, maintaining their reactivity after months of benchtop storage under ambient conditions.We demonstrated the utility of OACs in a variety of experiments including automated nanomole-scale couplings between an OAC derived from rivaroxaban and hundreds of diverse nucleophiles, as well as the late-stage derivatization of the natural product k252a.
Uehling, Mycah R.,King, Ryan P.,Krska, Shane W.,Cernak, Tim,Buchwald, Stephen L.
p. 405 - 408
(2019)
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Palladium complexes of o-xylylene-linked alkoxybenzimidazolin-2-ylidenes containing aryl N-substituents: Examples of C-H activation and the formation of a tri-nuclear palladium complex
Palladium complexes of new bidentate N-heterocyclic carbene (NHC) incorporating benzimidazolin- 2-ylidene units have been synthesized and structurally and spectroscopically characterised. The NHC ligands are furnished with aryl substituents on the nitroge
Simpson, Peter V.,Brown, David H.,Skelton, Brian W.,White, Allan H.,Baker, Murray V.
p. 79 - 91
(2015)
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Product selective reaction controlled by the combination of palladium nanoparticles, continuous microwave irradiation, and a co-existing solid; ligand-free Buchwald-Hartwig aminationvs.aryne amination
We have developed a continuous microwave irradiation-assisted Buchwald-Hartwig amination using our original Pd nanoparticle catalyst with a copper plate as a co-existing metal solid. In this methodology, a microwave-controlled product selectivity was achieved between Buchwald-Hartwig amination and aryne amination performed under strongly basic conditions and at a high reaction temperature, because a polar chemical species such as Ar-Pd-halogen might be activated selectively by microwave radiation. Moreover, our catalyst could be used repeatedly over 10 times, and the amount of Pd leaching could be suppressed to a low level.
Akiyama, Toshiki,Arai, Masayoshi,Arisawa, Mitsuhiro,Haneoka, Hitoshi,Harada, Kazuo,Murai, Kenichi,Murakami, Yosuke,Ohki, Yuuta,Ohta, Ryousuke,Sako, Makoto,Sirimangkalakitti, Natchanun,Suzuki, Takeyuki,Takahashi, Naoyuki,Takehara, Tsunayoshi,Yamada, Makito
supporting information
p. 8131 - 8137
(2021/10/29)

Coupling of Alternating Current to Transition-Metal Catalysis: Examples of Nickel-Catalyzed Cross-Coupling
The coupling of transition-metal to photoredox catalytic cycles through single-electron transfer steps has become a powerful tool in the development of catalytic processes. In this work, we demonstrated that transition-metal catalysis can be coupled to al
Bortnikov, Evgeniy O.,Semenov, Sergey N.
supporting information
p. 782 - 793
(2020/12/01)

Effect of Precatalyst Oxidation State in C-N Cross-Couplings with 2-Phosphinoimidazole-Derived Bimetallic Pd(I) and Pd(II) Complexes
We report the catalytic activity of two phosphinoimidazole-derived bimetallic palladium complexes in Pd-catalyzed amination reactions. Our studies demonstrate that the starting oxidation state (Pd(I) or Pd(II)) of the dimeric complex has a significant effect on the efficiency of the catalytic reaction. The corresponding Pd(I) complex shows higher reactivity in Buchwald-Hartwig aminations, while the Pd(II) complex is much more reactive in carbonylative amination reactions. These new dimeric palladium complexes provide good to excellent reactivity and yields in the amination reactions tested.
Martinez, Erin E.,Moreno, Mariur Rodriguez,Barksdale, Caleb A.,Michaelis, David J.
supporting information
p. 2763 - 2767
(2021/08/27)

Amination of Aryl Halides Mediated by Electrogenerated Nickel from Sacrificial Anode
Electrochemical C(sp2)?N couplings mediated by nickel salts generated from the sacrificial anode has been described for the first time. In this approach, the sacrificial nickel anode is employed as the sole source of nickel and the process, operationally simple to set up, enables the preparation of functionalized arylamine derivatives with moderate to good yields, under mild reaction conditions and without additional ligand. A cooperative process between the two electrodes is involved in the proposed mechanism.
Daili, Farah,Sengmany, Stéphane,Léonel, Eric
p. 2462 - 2469
(2021/06/28)

NiFe2O4@SiO2@ZrO2/SO42-/Cu/Co nanoparticles: A novel, efficient, magnetically recyclable and bimetallic catalyst for Pd-free Suzuki, Heck and C-N cross-coupling reactions in aqueous media
The novel heterogeneous bimetallic nanoparticles of Cu-Co were synthesized based on magnetic nanoparticles, and the magnetic nanocatalyst was characterized by XRD, FE-SEM, EDX mapping, BET, TEM, HRTEM, FTIR, TGA, and VSM. This catalyst was successfully applied as a recyclable magnetically catalyst in Heck, Suzuki, and C-N cross-coupling reactions with various aryl halides (iodides, bromides, and chlorides as challengeable substrates), with olefins, phenylboronic acid, and amines, respectively. We considered the rise of synergetic effects from the different Lewis acid and Br?nsted acid sites present in the catalyst. The catalyst was synthesized with cheap, available materials and a simple synthesis method. The catalyst can be separated easily using an external magnet. It was recycled for more than ten runs without a sensible loss of its catalytic activity, and no significant leaching of the Cu and Co quantity was observed. The significant benefits of the method are high-level generality, simple operation, and there are no heavy metals and toxic solvents. This is a quick, easy, efficacious and environmentally friendly protocol, and no by-products are formed in the reaction. These features make it an appropriate practical alternative protocol. In comparison with recent works, the other advantage of this catalyst is the synthesis of a wide variety of C-C and C-N bond derivatives (more than 40 derivatives). The other significant advantage is the low temperature of the reaction and the use of the least possible amount of the catalyst (0.003 g). The efficiency was good to excellent and the catalyst selectivity has been high. We aspire that our study inspires more interest to design novel catalysts based on using low-cost metal ions (such as cobalt and copper) in the cross-coupling reactions. This journal is
Alavi G., Seyyedeh Ameneh,Nasseri, Mohammad Ali,Kazemnejadi, Milad,Allahresani, Ali,Hussainzadeh, Mahdi
p. 7741 - 7757
(2021/05/13)

A base-free Chan–Lam reaction catalyzed by an easily assembled Cu(II)-carboxylate metal-organic framework
A new copper(II) metal-organic framework is constructed as a sustainable copper heterogeneous catalyst. Cu-DPTCA, with high catalytic activity, can effectively promote the Chan–Lam coupling reaction of arylboronic acids and amines without adding any base or additive.
Ma, Ruixuan,Qin, Jianhua,Shi, Lei,Zhang, Xinhai
p. 795 - 799
(2021/07/06)

L-Proline N-oxide dihydrazides as an efficient ligand for cross-coupling reactions of aryl iodides and bromides with amines and phenols
A novel catalytic system based on L-proline N-oxide/CuI was developed and applied to the cross-coupling reactions of various N- and O- nucleophilic reagents with aryl iodides and bromides. This strategy featured in the employment of an-proline derived dihydrazides N-oxide compound as the superior supporting ligand. By using this protocol, a variety of products, including N-arylimidazoles, N-arylpyrazoles, N-arylpyrroles, N-arylamines, and aryl ethers, were synthesized with up to 99% yield.
Ding, Zhiqiang,Nie, Nan,Chen, Tian,Meng, Lingxin,Wang, Gongshu,Chen, Zhangpei,Hu, Jianshe
supporting information

(2020/12/21)

Ligand compound for copper catalyzed aryl halide coupling reaction, catalytic system and coupling reaction
The invention provides a ligand compound capable of being used for copper catalyzed aryl halide coupling reaction, the ligand compound is a three-class compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group, and the invention also provides a catalytic system for the aryl halide coupling reaction. Thecatalytic system comprises a copper catalyst, a compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group adopted as a ligand, alkali and a solvent, and meanwhile, the invention also provides a system for the aryl halide coupling reaction adopting the catalyst system. The compound containing the 2-(substituted or non-substituted) aminopyridine nitrogen oxygen group can be used as the ligand for the copper catalyzed aryl chloride coupling reaction, and the ligand is stable under a strong alkaline condition and can well maintain catalytic activity when being used for the copper-catalyzed aryl chloride coupling reaction. In addition, the copper catalyst adopting the compound as the ligand can particularly effectively promote coupling of copper catalyzed aryl chloride and various nucleophilic reagents which are difficult to generate under conventional conditions, C-N, C-O and C-S bonds are generated, and numerous useful small molecule compounds are synthesized. Therefore, the aryl halide coupling reaction has a very good large-scale application prospect by adopting the copper catalysis system of the ligand.
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Paragraph 0086-0091; 0099

(2021/05/29)

Synthesis of N-heterocyclic carbene-Pd(II)-5-phenyloxazole complexes and initial studies of their catalytic activity toward the Buchwald-Hartwig amination of aryl chlorides
Three new N-heterocyclic carbene (NHC)-Pd(II) complexes using 5-phenyloxazole as the ancillary ligand have been obtained in moderate to good yields by a one-pot reaction of the corresponding imidazolium salts, palladium chloride and 5-phenyloxazole under mild conditions. Initial studies showed that one of the complexes is an efficient catalyst for the Buchwald-Hartwig amination of aryl chlorides with various secondary and primary amines under the varied catalyst loading of 0.01-0.05 mol%, thus it will enrich the chemistry of NHCs and give an alternative catalyst for the coupling of challenging while cost-low aryl chlorides.
Zhang, Zhi-Mao,Xu, Yu-Ting,Shao, Li-Xiong
(2021/04/19)

N-Heterocyclic Carbene Palladium(II) Amine Complexes: The Role of Primary Aryl- or Alkylamine Binding and Applications in the Buchwald-Hartwig Amination Reaction
N-heterocyclic carbene-palladium(II) amine complexes bearing primary aryl- or alkylamines were synthesized. The prepared complexes were characterized by single crystal X-ray diffraction as well as NMR spectroscopy. These complexes exhibited good catalytic activities for the Buchwald-Hartwig amination reaction of aryl chlorides to afford arylated anilines under mild conditions. All reactions were carried out in air and all starting materials were used as supplied without purification. 21 expected coupling products were obtained in moderate to high yields under optimum conditions.
Chen, Ming-Tsz,Hsu, Yu-Cheng
supporting information

(2021/12/24)

Selective C-O Bond Reduction and Borylation of Aryl Ethers Catalyzed by a Rhodium-Aluminum Heterobimetallic Complex
We report the catalytic reduction of a C-O bond and the borylation by a rhodium complex bearing an X-Type PAlP pincer ligand. We have revealed the reaction mechanism based on the characterization of the reaction intermediate and deuterium-labeling experiments. Notably, this novel catalytic system shows steric-hindrance-dependent chemoselectivity that is distinct from conventional Ni-based catalysts and suggests a new strategy for selective C-O bond activation by heterobimetallic catalysis.
Hara, Naofumi,Nakao, Yoshiaki,Saito, Teruhiko,Seki, Rin
p. 6388 - 6394
(2021/05/31)

Synthesis ofN-aryl amines enabled by photocatalytic dehydrogenation
Catalytic dehydrogenation (CD)viavisible-light photoredox catalysis provides an efficient route for the synthesis of aromatic compounds. However, access toN-aryl amines, which are widely utilized synthetic moieties,viavisible-light-induced CD remains a significant challenge, because of the difficulty in controlling the reactivity of amines under photocatalytic conditions. Here, the visible-light-induced photocatalytic synthesis ofN-aryl amines was achieved by the CD of allylic amines. The unusual strategy using C6F5I as an hydrogen-atom acceptor enables the mild and controlled CD of amines bearing various functional groups and activated C-H bonds, suppressing side-reaction of the reactiveN-aryl amine products. Thorough mechanistic studies suggest the involvement of single-electron and hydrogen-atom transfers in a well-defined order to provide a synergistic effect in the control of the reactivity. Notably, the back-electron transfer process prevents the desired product from further reacting under oxidative conditions.
Kim, Jungwon,Kim, Siin,Choi, Geunho,Lee, Geun Seok,Kim, Donghyeok,Choi, Jungkweon,Ihee, Hyotcherl,Hong, Soon Hyeok
p. 1915 - 1923
(2021/02/22)

Nickel-Catalyzed Amination of Aryl Chlorides with Amides
A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.
Li, Jinpeng,Huang, Changyu,Wen, Daheng,Zheng, Qingshu,Tu, Bo,Tu, Tao
supporting information
p. 687 - 691
(2021/01/09)

METHOD FOR PRODUCING AROMATIC AMINE COMPOUNDS FROM PHENOLS
PROBLEM TO BE SOLVED: To provide a method for producing an aromatic amine compound from phenols and amines with a high yield and a high selectivity, which includes ones subjected to polyfunctionalization, under relatively low temperature and relatively low pressure, without using an additive which gives a co-product having high environmental load. SOLUTION: Phenols and hydrogen are introduced into a first catalyst cartridge receiving a solid catalyst containing platinum group elements and continuously hydrogenated into cyclohexanones. The resultant cyclohexanones, along with amines selected from ammonia, primary amines and secondary amines, and hydrogen trapping agents are subsequently introduced into a second catalyst cartridge receiving a solid catalyst containing platinum group elements to continuously produce aromatic amine compounds by dehydration condensation and dehydrogenation with amines. SELECTED DRAWING: Figure 2 COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0017; 0051

(2021/06/04)

Preparation method of pyrazole bistriazolylphosphine compound
The invention discloses a preparation method of a pyrazole bistriazolylphosphine compound. The invention discloses a preparation method of a compound as shown in a formula I. The preparation method comprises the following step: under the action of an alkali, carrying out a phosphonation reaction process as shown in the specification on a compound as shown in a formula II and a compound as shown ina formula III in a solvent in the presence of protective gas to obtain the compound as shown in the formula I, wherein R1 is hydrogen, a C1-C6 alkyl group or a phenyl group, R2 and R3 are phenyl, R4and R5 are independently a C1-C6 alkyl group, a C3-C8 cycloalkyl group or a phenyl group and x is halogen. The pyrazolyl bistriazolylphosphine compound obtained by the preparation method disclosed bythe invention is stable in property, excellent in catalytic effect and high in selectivity, and can be applied to catalytic coupling of amine, boric acid compounds and halides.
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Paragraph 0212-0216; 0279-0301

(2020/05/30)

Green tea extract–modified silica gel decorated with palladium nanoparticles as a heterogeneous and recyclable nanocatalyst for Buchwald-Hartwig C–N cross-coupling reactions
A novel green tea extract–encapsulated silica gel decorated with in situ–generated Pd nanoparticles is reported as an efficient, green heterogeneous catalyst in the Buchwald-Hartwig C–N cross-coupling reaction. It was characterized by several analytical techniques. Thereafter, a wide range of aryl amines were synthesized in good to excellent yields by reaction of different substituted aryl halides and secondary amines over the catalyst. The material is sufficiently stable and could be used at least six times in a model Buchwald-Hartwig reaction without noticeable change in its catalytic activity. Heterogeneity of the catalyst was examined by a hot filtration test.
Veisi, Hojat,Tamoradi, Taiebeh,Karmakar, Bikash,Hemmati, Saba
(2019/11/28)

Cu(I)-anchored polyvinyl alcohol coated-magnetic nanoparticles as heterogeneous nanocatalyst in Ullmann-type C–N coupling reactions
In this paper, the preparation of a novel magnetic nanocatalyst (Fe3O4?PVA/CuCl) is described, which involves coating of polyvinyl alcohol (PVA) onto the surface of Fe3O4 nanoparticles and its subsequent coordination with CuCl catalyst. The nanocatalyst was characterized by various analytical methods, including Fourier-transform infrared, X-ray diffraction, inductively coupled plasma spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy, vibrating-sample magnetometry, and EDX elemental mapping. Moreover, the nanocatalyst was efficiently used in the N-arylation of amines via the formation of a carbon–nitrogen bond between the aryl halides and amines by Ullmann-type coupling reactions. The catalyst was sufficiently stable and can be reused for at least seven times in a model Ullmann reaction without remarkable alteration in its catalytic behavior. Heterogeneity of the catalyst was investigated by a hot filtration test.
Ahany Kamangar, Sheida,Hashemi Salehi, Mirmehdi,Hekmati, Malak,Hemmati, Saba,Yousefi, Mohammad
(2020/03/13)

Metal-free late-stage C(sp2)-H functionalization of: N -aryl amines with various sodium salts
Metal-free consecutive C(sp2)-X (X = Cl, Br, S, N) bond formations of N-aryl amines (cyclic, fused, carbamate, and aminium radicals) were achieved under mild conditions using [bis(trifluoroacetoxy)iodo]benzene (PIFA) and simple nonharmful sodium salts. This direct and selective C(sp2)-H functionalization showed excellent functional group compatibility, cost effectiveness, and late-stage applicability for the synthesis of biologically active natural products. Two mechanisms were proposed to explain the ortho- or para-preference, as well as the accelerating effect of CH3NO2
Mudithanapelli, Chandrashekar,Kim, Mi-Hyun
p. 450 - 464
(2020/02/03)

Visible Light-Mediated (Hetero)aryl Amination Using Ni(II) Salts and Photoredox Catalysis in Flow: A Synthesis of Tetracaine
We report a visible light-mediated flow process for C-N cross-coupling of (hetero)aryl halides with a variety of amine coupling partners through the use of a photoredox/nickel dual catalyst system. Compared to the method in batch, this flow process enables a broader substrate scope, including less-activated (hetero)aryl bromides and electron-deficient (hetero)aryl chlorides, and significantly reduced reaction times (10 to 100 min). Furthermore, scale up of the reaction, demonstrated through the synthesis of tetracaine, is easily achieved, delivering the C-N cross-coupled products in consistently high yield of 84% on up to a 10 mmol scale.
Park, Boyoung Y.,Pirnot, Michael T.,Buchwald, Stephen L.
p. 3234 - 3244
(2020/02/04)

A Co-Cu bimetallic magnetic nanocatalyst with synergistic and bifunctional performance for the base-free Suzuki, Sonogashira, and C-N cross-coupling reactions in water
A novel magnetically recyclable bimetallic catalyst was prepared by anchoring imidazolium moiety and PEG chains on Fe3O4 NPs and named as Fe3O4?PEG/Cu-Co. It was found to be a powerful catalyst for the Sonogashira, Suzuki, and C-N cross-coupling reactions in water as a green solvent without the need for any external base. Fe3O4?PEG/Cu-Co was well characterized with FT-IR, FE-SEM, TEM, VSM, EDX, ICP, UV-visible, CV, and XPS analyses. Optimum ranges of parameters such as time, temperature, and amount of catalyst were investigated by Design-Expert 10.0.7 software for C-C Suzuki, Sonogashira, and C-N cross-coupling reactions to find the optimum conditions. The catalyst was compatible with a variety of aryl halides and N-arenes and gave favorable coupling products with good to high yields for all of them. Hot filtration and Hg poisoning tests involving the nanocatalyst revealed the stability, low metal leaching, and heterogeneous nature of the catalyst. Reaction mechanisms were proposed by study of the UV-visible spectra in situ as well as hydroquinone tests during the progress of reactions. In situ XPS analysis was also used to study the reaction mechanism. To prove the synergistic performance of Co and Cu in the catalyst, its various homologues were synthesized and applied to a model reaction separately, and then their catalytic activities were investigated. Finally, the catalyst could be recovered from the reaction mixture simply, and reused for several cycles with a minimum loss in catalytic activity and performance.
Allahresani, Ali,Kazemnejadi, Milad,Nasseri, Mohammad Ali,Rezazadeh, Zinat
p. 10645 - 10660
(2020/09/18)

Integrating CuO?Fe2O3 Nanocomposites and Supramolecular Assemblies of Phenazine for Visible-Light Photoredox Catalysis
A photoredox catalytic ensemble consisting of CuO-Fe2O3 nanocomposites and oligomeric derivative of phenazine has been developed. The prepared system acts as an efficient photoredox catalyst for C?N bond formation reaction via SET mechanism under ‘green’ conditions (aerial environment, mixed aqueous media, recyclable), requiring less equivalents of base and amine substrate. The present study demonstrates the significant role of supramolecular assemblies as photooxidants and reductants upon irradiation and their important contribution towards the activation of the metallic centre through energy transfer and electron transfer pathways. The potential of oligomer 4: CuO-Fe2O3 has also been explored for C?C bond formation reactions via the Sonogashira protocol.
Kaur, Lovjot,Deol, Harnimarta,Kumar, Manoj,Bhalla, Vandana
supporting information
p. 892 - 898
(2020/03/04)

C–N Cross-coupling Reactions of Amines with Aryl Halides Using Amide-Based Pincer Nickel(II) Catalyst
Abstract: An approach to C–N cross-coupling reactions of aryl halides with amines in the presence of an amide-based pincer nickel(II) catalyst (2) is described. For 3?h reactions at 110?°C with 0.2?mol% catalyst, aryl bromides gave higher turnover numbers (TON) than the corresponding chlorides or iodides. Both primary and secondary amines could be used with the former giving higher TON. However, sterically hindered amines showed lower TON. In elucidating the mechanism of this nickel complex-catalyzed C–N cross coupling reaction it was found that the rate of reaction was unchanged in the presence of radical quenchers and a plausible Ni(I)–Ni(III) pathway is proposed. Graphic Abstract: [Figure not available: see fulltext.]Nickel pincer catalyst proved to be excellent catalyst for the C-N cross-coupling reaction with the high turnover number (TON) for 1° and 2° amines and different nonactivated aryl halides under optimum conditions.
Albkuri, Yahya M.,RanguMagar, Ambar B.,Brandt, Andrew,Wayland, Hunter A.,Chhetri, Bijay P.,Parnell, Charlette M.,Szwedo, Peter,Parameswaran-Thankam, Anil,Ghosh, Anindya
p. 1669 - 1678
(2019/12/27)

Photo-induced dealdehyding method
The invention provides a photo-induced dealdehyding method, and belongs to the technical field of organic synthesis. The photo-induced dealdehyding method comprises the following steps that a mixtureof a compound shown in the formula I and a solvent are reacted under an inert gas atmosphere and visible light irradiation, a dealdehyding product is obtained, and no photocatalyst is used in the whole process; wherein the structural formula of the formula I shown in the specification, R is a functional group and is selected from hydrogen, methyl, methoxyl, cyano, chlorine, bromine or fluorine. According to the photo-induced dealdehyding method, in the inert gas atmosphere, the compound shown in the formula (I) can be excited to generate carbon-oxygen bond homogeneous cracking through visiblelight irradiation, then free radical migration and double bond displacement are conducted, finally carbon monoxide is removed, aldehyde group removal is completed, no photocatalyst is needed in the whole process, operation is easy and convenient, and conditions are mild.
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Paragraph 0048-0053; 0126-0131

(2020/06/16)

CuI/2-Aminopyridine 1-Oxide Catalyzed Amination of Aryl Chlorides with Aliphatic Amines
A class of 2-aminopyridine 1-oxides are discovered to be effective ligands for the Cu-catalyzed amination of less reactive (hetero)aryl chlorides. A wide range of functionalized (hetero)aryl chlorides reacted with various aliphatic amines to afford the desired products in good to excellent yields under the catalyst of CuI/2-aminopyridine 1-oxides. Furthermore, the catalyst system worked well for the coupling of cyclic secondary amines and N-methyl benzylamine with (hetero)aryl chlorides.
Chen, Xiahong,He, Yongqiang,Liang, Yun,Liu, Wenjie,Wang, Deping,Xia, Xiaohong,Xu, Jiamin,Xu, Zhifeng,Zhang, Fuxing,Zhang, Xin
supporting information
p. 7486 - 7490
(2020/10/12)

Practical Transition-Metal-Free Protodeboronation of Arylboronic Acids in Aqueous Sodium Hypochlorite
A concise and practical method was developed for the protodeboronation of arylboronic acids under mild conditions in aqueous NaClO at 100 °C. The strategy is low-cost, transition-metal-free, and base-free.
Li, Minxin,Tang, Yanling,Gao, Jinchun,Rao, Gaoxiong,Mao, Zewei
p. 2039 - 2042
(2020/10/21)

Hydrodebromination of Aromatic Bromides Catalyzed by Unsupported Nanoporous Gold: Heterolytic Cleavage of Hydrogen Molecule
Unsupported nanoporous gold (AuNPore) is a highly efficient, practically applicable, and recyclable catalyst for hydrodebromination of aromatic bromides. The AuNPore-catalyzed hydrodebromination of aromatic bromides proceeded smoothly at relatively low hydrogen pressure and temperature to achieve good to excellent yields of the corresponding non-bromine variants. The selective hydrodebromination reaction occurred exclusively in the coexistence of chlorine atom. For the first time, a mechanistic study revealed that the H?H bond splits in a heterolysis manner on the surface of AuNPore to generate Au?H hydride species.
Bao, Ming,Feng, Xiujuan,Yamamoto, Yoshinori,Zhang, Sheng,Zhao, Yuhui
p. 4951 - 4957
(2020/09/09)

A Novel Modified Cross-Coupling of Phenols and Amines Using Dichloroimidazolidinedione (DCID)
Phenols are considered as an ideal alternative to aryl halides as coupling partners in cross-coupling reactions. In the present work a copper-catalyzed cross-coupling of phenols with various aromatic and aliphatic amines for the synthesis of secondary aryl amines using dichloroimidazolidinedione (DCID) as a new and efficient activating agent has been developed. Substituted phenols were compatible with the standard reaction conditions. The two proposed mechanisms, which are based on the oxidation addition of copper with Ar-OMCID (MCID: Monochloroimidazolidinedione), are also discussed.
Madankar, Kamelia,Mokhtari, Javad,Mirjafary, Zohreh
supporting information
p. 1725 - 1729
(2020/09/01)

Improved Process for the Palladium-Catalyzed C-O Cross-Coupling of Secondary Alcohols
An improved protocol for the Pd-catalyzed C-O cross-coupling of secondary alcohols is described. The use of biaryl phosphine L2 as the ligand was key to achieving efficient cross-coupling of (hetero)aryl chlorides with only a 20percent molar excess of the alcohol. Additionally, we observed an unusual reactivity difference between an electron-rich aryl bromide and the analogous aryl chloride, and deuterium-labeling suggested that currently unidentified pathways for reduction play an important role in explaining this disparity.
Zhang, Hong,Ruiz-Castillo, Paula,Schuppe, Alexander W.,Buchwald, Stephen L.
supporting information
p. 5369 - 5374
(2020/07/14)

Copper-Catalyzed Electrophilic Amination of Alkoxyarylsilanes
We report a copper-catalyzed amination reaction between simple alkoxyarylsilanes and N-benzoyloxyamines. Silver fluoride serves as a stoichiometric base as well as an indispensable activator that allows the catalytic process to proceed. Multiply alkoxylated arylsilanes, such as trialkoxyarylsilanes and dialkoxyarylsilanes were transformed into the corresponding tertiary anilines under mild reaction conditions.
Hitoshio, Kenshiro,Saito, Hayate,Shimokawa, Jun,Yorimitsu, Hideki,Zhang, Qian
(2020/07/04)

Catalyst-free photodecarbonylation ofortho-amino benzaldehyde
It is almost a consensus that decarbonylation of the aldehyde group (-CHO) needs to not only be mediated by transition metal catalysts, but also requires severe reaction conditions (high temperature and long reaction time). In this work, inspired by the “conformational-selectivity-based” design strategy, we broke this consensus and discovered a catalyst-free photodecarbonylation of the aldehyde group. It revealed that decarbonylation can be easily achieved with visible light irradiation by introducing a tertiary amine into theortho-position of the aldehyde group. A diverse array of tertiary amines is tolerated by our photodecarbonylation under mild conditions. Furthermore, the (QM) computations of the mechanism and the experiments on well-designed special substrates revealed that our photodecarbonylation depends on the conformational specificity of the aldehyde group and tertiary amine, and occurs through an unusual [1,4]-H shift and a subsequent [1,3]-H shift.
Li, Lamei,Wang, Songping,Wei, Wentao,Yan, Ming,Zhou, Jingwei
p. 3421 - 3426
(2020/06/25)

Nickel-Catalyzed Decarbonylative Amination of Carboxylic Acid Esters
The reaction of carboxylic acid derivatives with amines to form amide bonds has been the most widely used transformation in organic synthesis over the past century. Its utility is driven by the broad availability of the starting materials as well as the kinetic and thermodynamic driving force for amide bond formation. As such, the invention of new reactions between carboxylic acid derivatives and amines that strategically deviate from amide bond formation remains both a challenge and an opportunity for synthetic chemists. This report describes the development of a nickel-catalyzed decarbonylative reaction that couples (hetero)aromatic esters with a broad scope of amines to form (hetero)aryl amine products. The successful realization of this transformation was predicated on strategic design of the cross-coupling partners (phenol esters and silyl amines) to preclude conventional reactivity that forms inert amide byproducts.
Malapit, Christian A.,Borrell, Margarida,Milbauer, Michael W.,Brigham, Conor E.,Sanford, Melanie S.
supporting information
p. 5918 - 5923
(2020/04/08)

Transition-Metal-Catalyzed Amination of Aryl Fluorides
Arene activation via transition-metal (TM) η 6-coordination has merged as a powerful method to diversify the aromatic C-F bond, which is relatively less reactive due to its high bond energy. However, this strategy in general requires to use largely excess arenes or TM η 6-complexes as the substrates. Herein, we highlight our recent work on the catalytic S NAr amination of electron-rich and electron-neutral aryl fluorides that are inert in classical S NAr reactions. This protocol enabled by a Ru/hemilabile ligand catalyst covers a broad scope of substrates without wasting arenes. Mechanistic studies revealed that the nucleo?-philic substitution proceeded on a Ru η 6-arene complex, and the hemilabile ligand significant promoted the arene dissociation.
Kang, Qi-Kai,Li, Yuntong,Lin, Yunzhi,Shi, Hang
p. 1235 - 1239
(2020/07/20)

Ru(II)-Catalyzed Amination of Aryl Fluorides via η6-Coordination
We developed a Ru/hemilabile-ligand-catalyzed nucleophilic aromatic substitution (SNAr) of aryl fluorides as the limiting reagents. Significant ligand enhancement was demonstrated by the engagement of both electron-rich and neutral arenes in the SNAr amination without using excess arenes. Preliminary mechanistic studies revealed that the nucleophilic substitution proceeds on a η6-complex of the Ru catalyst and the substrate, and the hemilabile ligand facilitates dissociation of products from the metal center.
Kang, Qi-Kai,Li, Yuntong,Lin, Yunzhi,Shi, Hang
supporting information
p. 3706 - 3711
(2020/03/11)

Continuous Synthesis of Aryl Amines from Phenols Utilizing Integrated Packed-Bed Flow Systems
Aryl amines are important pharmaceutical intermediates among other numerous applications. Herein, an environmentally benign route and novel approach to aryl amine synthesis using dehydrative amination of phenols with amines and styrene under continuous-flow conditions was developed. Inexpensive and readily available phenols were efficiently converted into the corresponding aryl amines, with small amounts of easily removable co-products (i.e., H2O and alkanes), in multistep continuous-flow reactors in the presence of heterogeneous Pd catalysts. The high product selectivity and functional-group tolerance of this method allowed aryl amines with diverse functional groups to be selectively obtained in high yields over a continuous operation time of one week.
Ichitsuka, Tomohiro,Kobayashi, Shū,Koumura, Nagatoshi,Sato, Kazuhiko,Takahashi, Ikko
supporting information
p. 15891 - 15896
(2020/07/13)

Nickel-Catalyzed Amination of Aryl Thioethers: A Combined Synthetic and Mechanistic Study
Herein, we report a nickel-1,2-bis(dicyclohexylphosphino)ethane (dcype) complex for the catalytic Buchwald-Hartwig amination of aryl thioethers. The protocol shows broad applicability with a variety of different functional groups tolerated under the catalytic conditions. Extensive organometallic and kinetic studies support a nickel(0)-nickel(II) pathway for this transformation and revealed the oxidative addition complex as the resting state of the catalytic cycle. All the isolated intermediates have proven to be catalytically and kinetically competent catalysts for this transformation. The fleeting transmetalation intermediate has been successfully synthesized through an alternative synthetic organometallic pathway at lower temperature, allowing for in situ NMR study of the C-N bond reductive elimination step. This study addresses key factors governing the mechanism of the nickel-catalyzed Buchwald-Hartwig amination process, thus improving the understanding of this important class of reactions.
Bismuto, Alessandro,Delcaillau, Tristan,Müller, Patrick,Morandi, Bill
p. 4630 - 4639
(2020/05/19)

Copper(ii)-catalyzed c-n coupling of aryl halides and n-nucleophiles promoted by quebrachitol or diethylene glycol
Herein, we report the natural ligand quebrachitol (QCT) as a promoter for a Cu(II) catalyst, which is highly effective for N-Arylation of various amines and related aryl halides. A series of diarylamine derivatives were obtained in high yields by using diethylene glycol (DEG) as both ligand and solvent. The C-N coupling reactions proceed under mild conditions and exhibit good functional group tolerance.
Chen, Guoliang,Chen, Yuanguang,Du, Fangyu,Fu, Yang,Wu, Ying,Zhou, Qifan
supporting information
p. 2161 - 2168
(2019/11/25)

Palladium nanoparticles supported on cysteine-functionalized MNPs as robust recyclable catalysts for fast O- and N-arylation reactions in green media
A magnetically robust recyclable nanocatalyst was fabricated by immobilizing of Pd onto the surface of cysteine-functionalized magnetic nanoparticles (MNPs?Cys-Pd). This nanocatalyst was characterized using various techniques such as FT-IR, XRD, TEM, SEM, EDX, VSM, and ICP. The application of catalyst (MNPs?Cys-Pd) was investigated for O-arylation and N-arylation reactions. This phosphine-free complex was found as highly efficient heterogeneous catalyst in green media and mild reaction conditions. In addition, it gave excellent recyclability without significant deactivation after ten cycles.
Hajipour, Abdol R.,Khorsandi, Zahra,Fatemeh Mohammadi Metkazini
(2019/08/12)

Facile synthesis of Pd(ii) and Ni(ii) pincer carbene complexes by the double C-H bond activation of a new hexahydropyrimidine-based bis(phosphine): Catalysis of C-N couplings
Hexahydropyrimidine-based bis(phosphine), a pro-NHC ligand, was synthesized in one step and excellent yield. It underwent spontaneous double C-H bond activation to give cationic pincer NHC complexes of the type [(PCP)MCl]X (M = Pd, Ni and X = Cl, BF4) in the absence of any external reagents. Their structures were determined by X-ray diffraction methods and the mechanism of formation of palladium carbene complexes as analyzed by DFT calculations showed two transition states. The Pd(ii) carbene complex effectively catalyzes a few C-N cross coupling reactions.
Subramaniyan, Vasudevan,Dutta, Bidisa,Govindaraj, Anbarasu,Mani, Ganesan
p. 7203 - 7210
(2019/06/13)

Robust Buchwald-Hartwig amination enabled by ball-milling
An operationally simple mechanochemical method for the Pd catalysed Buchwald-Hartwig amination of arylhalides with secondary amines has been developed using a Pd PEPPSI catalyst system. The system is demonstrated on 30 substrates and applied in the context of a target synthesis. Furthermore, the performance of the reaction under aerobic conditions has been probed under traditional solution and mechanochemical conditions, the observations are discussed herein.
Cao, Qun,Nicholson, William I.,Jones, Andrew C.,Browne, Duncan L.
supporting information
p. 1722 - 1726
(2019/02/20)

Recyclable bimetallic CuMoO4 nanoparticles for C-N cross-coupling reaction under mild conditions
Herein we disclosed inexpensive copper(ii) bimetallic CuMoO4 nanoparticles for the C-N cross-coupling reaction of alkyl and aryl amines with haloarenes. The reaction proceeds under mild and ligand free conditions. The catalyst is recyclable and effective for a wide range of amines and haloarenes. Here, the efficiency of the Cu(ii) catalyst is increased by doping molybdenum metal. The bimetallic nanoparticles are anticipated to proceed via normal oxidative addition and reductive eliminations.
Panigrahi, Reba,Panda, Subhalaxmi,Behera, Pradyota Kumar,Sahu, Santosh Kumar,Rout, Laxmidhar
supporting information
p. 19274 - 19278
(2019/12/24)

Electrochemical Regioselective Bromination of Electron-Rich Aromatic Rings Using n Bu 4 NBr
Electrochemical regioselective bromination of electron-rich aromatic rings using stoichiometric tetrabutylammonium bromide (n Bu 4 NBr) has been accomplished under mild conditions. This protocol provides an environmentally friendly and simple way for the construction of C-Br bond in moderate to high yields with wide functional group tolerance.
Bai, Ya,Che, Xin,Liu, Nian,Ning, Shulin,Shi, Lingling,Wang, Shutao,Wang, Siyu,Xiang, Jinbao,Xie, Wenxia
supporting information
p. 1313 - 1316
(2019/06/20)

Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes
Photoexcited electron-hole pairs on a semiconductor surface can engage in redox reactions with two different substrates. Similar to conventional electrosynthesis, the primary redox intermediates afford only separate oxidized and reduced products or, more rarely, combine to one addition product. Here, we report that a stable organic semiconductor material, mesoporous graphitic carbon nitride (mpg-CN), can act as a visible-light photoredox catalyst to orchestrate oxidative and reductive interfacial electron transfers to two different substrates in a two- or three-component system for direct twofold carbon–hydrogen functionalization of arenes and heteroarenes. The mpg-CN catalyst tolerates reactive radicals and strong nucleophiles, is straightforwardly recoverable by simple centrifugation of reaction mixtures, and is reusable for at least four catalytic transformations with conserved activity.
Ghosh, Indrajit,Khamrai, Jagadish,Savateev, Aleksandr,Shlapakov, Nikita,Antonietti, Markus,K?nig, Burkhard
p. 360 - 366
(2019/08/15)

Nickel-catalyzed N-arylation of amines with arylboronic acids under open air
In this study, a well-defined, novel NHC-Ni complex was developed and used to catalyze the N-arylation of alkyl- and arylamines with arylboronic acids in a rare version of Chan-Lam coupling. Although the same coupling using copper catalysts has been widely studied, the nickel-catalyzed version is rare and normally requires 10–20 mol% catalyst loading. This novel NHC-Ni complex in combination with 4,4′-dimethyl-2,2′-bipyridine, however, proved to be an effective catalyst that lowered the required catalyst loading to only 2.0 mol%.
Ando, Shin,Hirota, Yurina,Matsunaga, Hirofumi,Ishizuka, Tadao
supporting information
p. 1277 - 1280
(2019/04/10)

C?N Cross-Coupling Reactions Under Mild Conditions Using Singlet Di-Radical Nickel(II)-Complexes as Catalyst: N-Arylation and Quinazoline Synthesis
Herein we report a cost-effective synthetic approach for C?N cross-coupling reactions of a broad array of nitrogen nucleophiles and aryl halides under mild conditions. These reactions are catalyzed by an inexpensive, air-stable, earth-abundant and easy-to-prepare singlet di-radical nickel(II)-catalyst containing two antiferromagnetically coupled single-electron oxidized diiminosemiquinonato type ligands. This protocol provides an alternative method for C?N cross-coupling reactions avoiding nickel(0)/nickel(II) or nickel(I)/nickel(III) redox processes via cooperative participation of metal and ligand-centered redox events. Besides a wide range of N-arylation reactions, by judicious choice of aryl halides and nitrogen nucleophiles the synthesis of a variety of polysubstituted quinazolines has been achieved in moderate to good yields under relatively mild reaction conditions. Our catalyst has been found to be almost equally effective in quinazoline synthesis via C?N cross-coupling of (i) 2-bromobenzylamine with benzamide, and (ii) 2-bromobenzylbromide with amidine. Control experiments and DFT studies were performed to improve the understanding of the cooperative participation of ligand and metal (nickel)-centered redox events during oxidative addition/reductive elimination processes of the catalytic cycle and to shed light on the plausible mechanistic pathway of the C?N cross-coupling reactions. (Figure presented.).
Sikari, Rina,Sinha, Suman,Chakraborty, Gargi,Das, Siuli,van Leest, Nicolaas Petrus,Paul, Nanda D.
supporting information
p. 4342 - 4353
(2019/08/21)

Iron-Catalyzed/Mediated C-N Bond Formation: Competition between Substrate Amination and Ligand Amination
Iron catalyzed carbon-nitrogen bond formation reactions of a wide variety of nucleophiles and aryl halides using well-defined iron-complexes featuring redox noninnocent 2-(arylazo)-1,10-phenanthroline (L1) ligands are reported. Besides substrate centered C-N coupling, C-N bond formation reactions were also observed at the ortho- and para-positions of the phenyl ring of the coordinated azo-aromatic scaffolds affording new tetradentate ligands, 2-N-aryl-(2-arylazo)-1,10-phenanthroline (L2), and tridentate ligands, 4-N-aryl-(2-arylazo)-1,10-phenanthroline (L3), respectively. Control experiments and mechanistic studies reveal that the complex [FeL1Cl2] (1) undergoes in situ reduction during the catalytic reaction to produce the monoanionic complex [1]-, which then acts as the active catalyst. The metal (iron) and the coordinated ligand were found to work in a cooperative manner during the transfer processes involved in the fundamental steps of the catalytic cycle. Detailed experimental and theoretical (DFT) studies were performed to get insight into the competitive substrate versus ligand centered amination reactions.
Sinha, Suman,Sikari, Rina,Sinha, Vivek,Jash, Upasona,Das, Siuli,Brand?o, Paula,Demeshko, Serhiy,Meyer, Franc,De Bruin, Bas,Paul, Nanda D.
p. 1935 - 1948
(2019/01/25)

Structure Ligation Relationship of Amino Acids for the Amination Cross-Coupling Reactions
The structure ligation relationship (SLR) of amino acids (AAs) for the cross-coupling aminations was examined. While AA ligated C-N cross-couplings under Pd and Ni catalysis were minor or ineffective, the AA ligated Cu-catalyzed C-N cross-couplings were promising particularly with the use of l-methionine. The roles of -NH2, -CO2H, and -S- of l-methionine were investigated and found critical for their ligation efficiency. The finding was compatible with aromatic as well as aliphatic amines including tautomerizable N-heteroarenes.
Vaidya, Gargi Nikhil,Khan, Arif,Verma, Hansa,Kumar, Sanjeev,Kumar, Dinesh
p. 3004 - 3010
(2019/03/07)

New Insights into the Reaction Capabilities of Ionic Organic Bases in Cu-Catalyzed Amination
The application of ionic organic bases in the copper-catalyzed amination reaction (Ullmann reaction) has been studied at room temperature, with sub-mol-% catalyst loadings, and with more challenging amines at elevated temperatures. The cation present in the base has been shown to have little effect on the reaction at standard catalyst and ancillary ligand loadings, whereas the choice of anion is crucial for good reactivity. A substrate scope carried out at room temperature with the best performing bases, TBAM and TBPM, showed both bases to be highly effective under these mild reaction conditions. Moreover, under sub-mol % catalyst loadings and room temperature conditions, TBPM gave good to excellent yields for a number of different amines and functionalized aryl iodides (14 examples). However, reactions involving more challenging amines gave little or no yield. By using more forceful conditions (120 °C) moderate to excellent yields of cross-coupled products containing more challenging amines was achievable using TBPM and to a lesser extent with TBAM. As part of this work a study on the stability of the organic bases at 120 °C was undertaken. TBAM is shown to decompose to give nBu3N and mono-butylmalonate at higher temperatures, and this can be correlated to a decrease in performance in the coupling reaction. The phosphonium cations in TBPM did not undergo analogous reactivity but were shown instead to experience some degree of deprotonation at the α-CH2 to generate phosphonium ylides. This however did not lead to a significantly degradation in the activity of the TBPM in the cross-coupling reaction.
Lo, Quintin A.,Sale, David,Braddock, D. Christopher,Davies, Robert P.
p. 1944 - 1951
(2019/02/19)

METHODS FOR FORMING ARYL CARBON-NITROGEN BONDS USING LIGHT AND PHOTOREACTORS USEFUL FOR CONDUCTING SUCH REACTIONS
The disclosure relates to a method for forming aryl carbon-nitrogen bonds and to photoreactors useful in these and other light-driven reactions. The method comprises contacting an aryl halide with an amine in the presence of a Ni salt catalyst solution and an optional base, thereby forming a reaction mixture; exposing the reaction mixture to light under reaction condition sufficient to produce the aryl carbon-nitrogen bonds. In certain embodiments, the amine may be present in a molar excess to the aryl halide. In certain embodiments, the Ni salt catalyst solution includes a Ni(II) salt and a polar solvent, wherein the Ni(II) salt is dissolved in the polar solvent. In certain embodiments, the reactions conditions include holding the reaction mixture at between about room temperature and about 80° C. for between about 1 hour and about 20 hours such that at least about 50% yield is obtained.
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Paragraph 0097-0098; 0162-0163

(2019/11/22)

Direct Installation of a Silyl Linker on Ready-Made NHC Ligands: Immobilized NHC-Pd Complex for Buchwald-Hartwig Amination
An immobilized N-heterocyclic carbene (NHC)-Pd complex was prepared via direct silyl linker installation onto the imidazole backbone of commercially available 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) ligand. The IPr backbone was lithiated and treated with Me2SiCl2 to afford ClMe2Si-IPr, which reacted with [Pd(π-allyl)Cl]2 to yield a ClMe2Si-IPr-Pd complex, and this was immobilized on Wang resin. The immobilized NHC-Pd complex facilitated quantitative Buchwald-Hartwig amination of aryl chlorides within 10 min, even at a low Pd loading of 0.2 mol %. The catalyst could be removed from the reaction mixture by simple filtration, and Pd leaching into the reaction medium was suppressed to below 1 ppm.
Mizusaki, Tomoteru,Matsumoto, Kazuhiro,Takeuchi, Katsuhiko,Fukaya, Norihisa,Takagi, Yukio,Choi, Jun-Chul
supporting information
p. 1872 - 1876
(2019/05/07)