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Synthesis and characterization of palladium nanoparticles immobilized on graphene oxide functionalized with triethylenetetramine or 2,6-diaminopyridine and application for the Suzuki cross-coupling reaction
Graphene oxide (GO) was functionalized with two organic ligands, triethylenetetramine (TETA) or 2,6-diaminopyridine (DAP), followed by palladium nanoparticles (Pd NPs) for the synthesis of Pd NPs/GO-TETA and Pd NPs/GO-DAP nanocomposites, respectively. The two heterogeneous nanocomposites were fully characterized and their efficiency was investigated for C[sbnd]C bond formation for the synthesis of biaryl compounds via the Suzuki cross-coupling reaction of aryl halides with arylboronic acid derivatives. The obtained results indicated that the Pd NPs/GO-TETA nanocomposite was more effective in the Suzuki coupling reaction as compared to Pd NPs/GO-DAP. Thus, the Suzuki cross-coupling reaction of different aryl halides with arylboronic acid derivatives using Pd NPs/GO-TETA nanocomposite catalyst in the presence of Na2CO3 as base in DMF/H2O (1/1) as solvent at 90 °C was carried out to afford the desired biaryl compounds in high to excellent yields (81–100%) and short reaction times (10–90 min). Additionally, Pd NPs/GO-TETA nanocomposite can be recovered and reused for 8 consecutive runs without any apparent loss of its catalytic activity, proving its high stability and potential use in organic transformations.
Boukherroub, Rabah,Mirza-Aghayan, Maryam,Mohammadi, Marzieh
(2021/11/22)

Nickel-Catalyzed Reductive Cross-Coupling of Benzylic Sulfonium Salts with Aryl Iodides
A nickel-catalyzed cross-electrophile coupling of benzylic sulfonium salts with aryl iodides has been developed, providing direct access to diarylalkanes from readily available and stable coupling partners. Preliminary mechanistic studies suggest that the C-S bond cleavage proceeds through a single-electron transfer process to generate a benzylic radical.
Wang, Wei,Yao, Ken,Wu, Fan
supporting information
p. 361 - 366
(2022/03/07)

Desulfurative Ni-Catalyzed Reductive Cross-Coupling of Benzyl Mercaptans/Mercaptoacetates with Aryl Halides
The C-S activation and sulfur removal from native thiols is challenging, which limits their application as feedstock materials in organic synthesis despite their natural abundance. Herein, we introduce a per-/polyfluoroaryl moiety, which serves as a redox-active scaffold, into sp3-hybridized thiols to activate the C-S bond. Using a Ni catalyst with MgBr2 as an additive, the S group can be removed to yield an aliphatic radical that can react with an aryl halide in a reductive cross-coupling.
Chan, Cheng-Lin,Hsu, Che-Ming,Lee, Shao-Chi,Li, Li-Yun,Liao, Hsuan-Hung,Mi?oza, Shinje,Tsai, Hao-En,Tsai, Zong-Nan,Tsao, Yong-Ting
(2022/02/07)

METHOD FOR PRODUCING ARENE COMPOUNDS AND ARENE COMPOUNDS PRODUCED BY THE SAME
Provided is a method for producing (alkyl)arene compounds represented by Formulae 3-1, 3-2, and 3-3 by the Friedel-Crafts alkylation reaction of alkyl halide compounds and arene compounds using organic phosphine compounds as a catalyst.
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(2021/06/26)

Photocatalytic Dehydroxymethylative Arylation by Synergistic Cerium and Nickel Catalysis
Under mild reaction conditions with inexpensive cerium and nickel catalysts, easily accessible free alcohols can now be utilized as operationally simple and robust carbon pronucleophiles in selective C(sp3)-C(sp2) cross-couplings. Facilitated by automated high-throughput experimentation, sterically encumbered benzoate ligands have been identified for robust cerium complexes, enabling the synergistic cooperation of cerium catalysis in the emerging metallaphotoredox catalysis. A broad range of free alcohols and aromatic halides can be facilely employed in this transformation, representing a new paradigm for the C(sp3)-C(sp2) bond construction between free alcohols and aryl halides with the extrusion of formaldehyde. Moreover, mechanistic investigations have been conducted, leading to the identification of a tribenzoate cerium(III) complex as a viable intermediate.
Chen, Yuegang,Wang, Xin,He, Xu,An, Qing,Zuo, Zhiwei
supporting information
p. 4896 - 4902
(2021/05/04)

Nickel-Catalyzed Cross-Coupling of Aryl 2-Pyridyl Ethers with Organozinc Reagents: Removal of the Directing Group via Cleavage of the Carbon-Oxygen Bonds
Reaction of aryl 2-pyridyl ethers with arylzinc reagents under catalysis of NiCl2(PCy3)2 affords aryl-aryl cross-coupling products via selective cleavage of CAr-OPy bonds. The reaction features a wide substrate range and good compatibility of functional groups. β-H-free alkylzinc reagents are also applicable as the nucleophiles in the transformation, whereas β-H-containing alkylzinc reagents lead to a mixture of cross-coupling and hydrogenation products.
Dai, Wei-Can,Yang, Bo,Xu, Shi-He,Wang, Zhong-Xia
p. 2235 - 2243
(2021/02/01)

para-Selective arylation and alkenylation of monosubstituted arenes using thianthreneS-oxide as a transient mediator
Using thianthreneS-oxide (TTSO) as a transient mediator,para-arylation and alkenylation of mono-substituted arenes have been demonstratedviaapara-selective thianthrenation/Pd-catalyzed thio-Suzuki-Miyaura coupling sequence under mild conditions. This reaction features a broad substrate scope, and functional group and heterocycle tolerance. The versatility of this approach was further demonstrated by late-stage functionalization of complex bioactive scaffolds, and direct synthesis of some pharmaceuticals, including Tetriprofen, Ibuprofen, Bifonazole, and LJ570.
Chen, Xiao-Yue,Nie, Xiao-Xue,Wu, Yichen,Wang, Peng
p. 5058 - 5061
(2020/05/18)

Preparation method of para-substituted aryl compound
The invention discloses a preparation method of a para-substituted aryl compound shown as a formula (I) which is described in the specfication. The preparation method is characterized by comprising the following step of: subjecting an aryl sulfonium salt shown as a formula (II) which is described in the specfication and boride to a coupling reaction in a solvent in an inert atmosphere under the action of alkali and a palladium catalyst to obtain the para-substituted aryl compound. According to the method, mono-substituted aromatic hydrocarbon is taken as a substrate, the aryl sulfonium salt isconstructed in situ, and the palladium catalyst catalyzes the aryl sulfonium salt constructed in situ to undergo the Suzuki-Miyaura coupling reaction, so a mono-substituted aromatic hydrocarbon para-arylation or alkenylation product is constructed quickly and efficiently. The method is mild in conditions, high in substrate universality and wide in tolerance of a heterocyclic coupling substrate.
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(2020/06/09)

NHC-Nickel Catalyzed C-N Bond Cleavage of Mono-protected Anilines for C-C Cross-Coupling
A Ni-catalyzed aryl C-N bond cleavage of mono-protected anilines, N-arylsulfonamides, has been developed. A new N-heterocyclic carbene derived from benzoimidazole shows high reactivity for the C-N cleavage/C-C cross-coupling reaction. The ortho-directing group is not required to break the C-N bond of sulfonyl-protected anilines, which are not limited to π-extended anilines. The mechanistic studies have revealed that a sulfamidomagnesium salt is the key coupling intermediate.
Xia, Ji-Bao,Zhang, Zheng-Bing
p. 9609 - 9613
(2020/12/21)

Iridium-Catalysed Reductive Deoxygenation of Ketones with Formic Acid as Traceless Hydride Donor
An iridium-catalysed deoxygenation of ketones and aldehydes is achieved, with formic acid as hydride donor and water as co-solvent. At low catalyst loading, a number of 4-(N,N-disubstituted amino) aryl ketones are readily deoxygenated in excellent yields and chemoselectivity. Numerous functional groups, especially phenolic and alcoholic hydroxyls, secondary amine, carboxylic acid, and alkyl chloride, are well tolerable. Geminally dideuterated alkanes are obtained with up to 90% D incorporation, when DCO2D and D2O are used in place of their hydrogenative counterparts. The activating 4-(N,N-disubstituted amino)aryl groups have been demonstrated to undergo a variety of useful transformations. The deoxygenative deuterations have been used to prepare a deuterated drug molecule Chlorambucil-4,4-d2. (Figure presented.).
Yang, Zhiheng,Zhu, Xueya,Yang, Shiyi,Cheng, Weiyan,Zhang, Xiaojian,Yang, Zhanhui
p. 5496 - 5505
(2020/10/22)

Transition-Metal-Free C-C, C-O, and C-N Cross-Couplings Enabled by Light
Transition-metal-catalyzed cross-couplings to construct C-C, C-O, and C-N bonds have revolutionized chemical science. Despite great achievements, these metal catalysts also raise certain issues including their high cost, requirement of specialized ligands, sensitivity to air and moisture, and so-called "transition-metal-residue issue". Complementary strategy, which does not rely on the well-established oxidative addition, transmetalation, and reductive elimination mechanistic paradigm, would potentially eliminate all of these metal-related issues. Herein, we show that aryl triflates can be coupled with potassium aryl trifluoroborates, aliphatic alcohols, and nitriles without the assistance of metal catalysts empowered by photoenergy. Control experiments reveal that among all common aryl electrophiles only aryl triflates are competent in these couplings whereas aryl iodides and bromides cannot serve as the coupling partners. DFT calculation reveals that once converted to the aryl radical cation, aryl triflate would be more favorable to ipso substitution. Fluorescence spectroscopy and cyclic voltammetry investigations suggest that the interaction between excited acetone and aryl triflate is essential to these couplings. The results in this report are anticipated to provide new opportunities to perform cross-couplings.
Liu, Wenbo,Li, Jianbin,Querard, Pierre,Li, Chao-Jun
p. 6755 - 6764
(2019/05/06)

Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides
For the first time, by using H3PO3/I2 system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H3PO3, benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.
Gao, Jing,Han, Li-Biao,Ma, Yonghao,Tang, Zilong,Wu, Xiaofang,Xiao, Jing
p. 22343 - 22347
(2019/07/31)

A SO2F2 mediated mild, practical, and gram-scale dehydroxylative transforming primary alcohols to quaternary ammonium salts
A simple, practical and gram-scale process for direct transformation of primary alcohols or silyl ethers to ammonium salts was developed. This method has the feathers of easy work-up (a simple filtration), mild condition, high yield, great practicality and robustness. And the application of the ammonium salts in Suzuki coupling reaction was also accomplished.
Zhao, Chuang,Zha, Gao-Feng,Fang, Wan-Yin,Alharbi, Njud S.,Qin, Hua-Li
p. 4648 - 4656
(2019/07/12)

Deoxygenative cross-electrophile coupling of benzyl chloroformates with aryl iodides
This work describes Ni-catalyzed cross-electrophile coupling of benzyl chloroformate derivatives with aryl iodides that generates a wide range of diaryl methane products. The mild reaction conditions merit the C-O bond radical fragmentation of benzyl chloroformates via halide abstraction or a single electron reduction by a Ni catalyst. This work offers a new substrate type for cross-electrophile couplings.
Pan, Yingying,Gong, Yuxin,Song, Yanhong,Tong, Weiqi,Gong, Hegui
supporting information
p. 4230 - 4233
(2019/05/06)

The Dual Role of Benzophenone in Visible-Light/Nickel Photoredox-Catalyzed C?H Arylations: Hydrogen-Atom Transfer and Energy Transfer
A dual catalytic protocol for the direct arylation of non-activated C(sp3)?H bonds has been developed. Upon photochemical excitation, the excited triplet state of a diaryl ketone photosensitizer abstracts a hydrogen atom from an aliphatic C?H bond. This inherent reactivity was exploited for the generation of benzylic radicals which subsequently enter a nickel catalytic cycle, accomplishing the benzylic arylation.
Dewanji, Abhishek,Krach, Patricia E.,Rueping, Magnus
supporting information
p. 3566 - 3570
(2019/02/26)

Construction of Di(hetero)arylmethanes Through Pd-Catalyzed Direct Dehydroxylative Cross-Coupling of Benzylic Alcohols and Aryl Boronic Acids Mediated by Sulfuryl Fluoride (SO2F2)
A practical Pd-catalyzed direct dehydroxylative coupling of (hetero)benzylic alcohols with (hetero)arylboronic acids for the constructions of di(hetero)arylmethane derivatives under SO2F2 was described. This new method provided a strategically distinct approach to di(hetero)arylmethane derivatives from readily available and abundant benzylic alcohols under mild condition.
Zhao, Chuang,Zha, Gao-Feng,Fang, Wan-Yin,Rakesh,Qin, Hua-Li
p. 1801 - 1807
(2019/02/07)

An Efficient Ga(OTf)3/Isopropanol Catalytic System for Direct Reduction of Benzylic Alcohols
This study aims to report the first gallium-catalyzed direct reduction of benzylic alcohols using isopropanol as a reductant. The reaction proceeds via gallium catalyst-assisted hydride transfer of the in situ-generated benzylic isopropyl ether. The method generates only water and acetone as byproducts and thus provides an atom-economic and environmentally friendly approach to the synthesis of di- and triarylmethanes, which are important substructures in various bioactive compounds and functional materials. (Figure presented.).
Sai, Masahiro
supporting information
p. 4330 - 4335
(2018/10/15)

Chlorotrimethylsilane and Sodium Iodide: A Remarkable Metal-Free Association for the Desulfurization of Benzylic Dithioketals under Mild Conditions
A novel metal-free process allowing the reductive desulfurization of various benzylic dithioketals to afford diarylmethane and benzylester derivatives with good to excellent yields is reported. At room temperature, this mild reduction process requires only the use of TMSCl and NaI in CH2Cl2 and tolerates a large variety of functional groups. (Figure presented.).
Zhao, Guangkuan,Yuan, Ling-Zhi,Alami, Mouad,Provot, Olivier
p. 2522 - 2536
(2018/05/14)

Decarboxylative Negishi Coupling of Redox-Active Aliphatic Esters by Cobalt Catalysis
A cobalt-catalyzed decarboxylative Negishi coupling reaction of redox-active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkyl–aryl, alkyl–alkenyl, and alkyl–alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (±)-preclamol highlight the synthetic potential of this method. Mechanistic studies indicated that a radical mechanism is involved.
Liu, Xu-Ge,Zhou, Chu-Jun,Lin,Han, Xiang-Lei,Zhang, Shang-Shi,Li, Qingjiang,Wang, Honggen
p. 13096 - 13100
(2018/09/21)

Gold(I)-catalyzed Benzylation of (Hetero)aryl Boronic Acids with (Hetero)benzyl Bromides by the Strategy of a SN2-type Reaction
Herein, the first example of gold-catalyzed benzylation of (hetero)aryl boronic acids with (hetero)benzyl bromides to give the corresponding cross-coupling products in moderate to good yields is reported. The reaction proceeds through a possible intermolecular SN2-type reaction pathway to give a wide variety of di(hetero)arylmethanes as the desired products. An intriguing reaction mechanism has been proposed on the basis of control experiments, 31P-NMR spectroscopic detection and DFT calculations.
Zang, Wenqing,Wei, Yin,Shi, Min
supporting information
p. 2791 - 2795
(2018/09/20)

Modular Functionalization of Arenes in a Triply Selective Sequence: Rapid C(sp2) and C(sp3) Coupling of C?Br, C?OTf, and C?Cl Bonds Enabled by a Single Palladium(I) Dimer
Full control over multiple competing coupling sites would enable straightforward access to densely functionalized compound libraries. Historically, the site selection in Pd0-catalyzed functionalizations of poly(pseudo)halogenated arenes has been unpredictable, being dependent on the employed catalyst, the reaction conditions, and the substrate itself. Building on our previous report of C?Br-selective functionalization in the presence of C?OTf and C?Cl bonds, we herein complete the sequence and demonstrate the first general arylations and alkylations of C?OTf bonds (in I dimer. This allowed the realization of the first general and triply selective sequential C?C coupling (in 2D and 3D space) of C?Br followed by C?OTf and then C?Cl bonds.
Keaveney, Sinead T.,Kundu, Gourab,Schoenebeck, Franziska
supporting information
p. 12573 - 12577
(2018/09/18)

Transition-Metal-Free C-H Arylation of Unactivated Arenes with 8-Hydroxyquinoline as a Promoter
A method for the transition-metal-free direct C-H arylation of unactivated arenes is developed with aryl bromides as substrates and 8-hydroxyquinoline as an efficient promoter. A variety of biaryl compounds with structural diversity are obtained in moderate to high yields. Mechanistic studies reveal that the reaction proceeds via a homolytic aromatic substitution pathway.
Zheng, Xuehua,Wu, Xu-Nian,Chen, Jing-Yi,Luo, Hai-Bin,Wu, Deyan,Wu, Yinuo
p. 1721 - 1727
(2018/02/06)

Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
p. 4622 - 4627
(2018/05/22)

Transition-Metal-Free Suzuki-Type Cross-Coupling Reaction of Benzyl Halides and Boronic Acids via 1,2-Metalate Shift
Cross-coupling of organoboron compounds with electrophiles (Suzuki-Miyaura reaction) has greatly advanced C-C bond formation and has been well received in medicinal chemistry. During the past 50 years, transition metals have played a central role throughout the catalytic cycle of this important transformation. In this process, chemoselectivity among multiple carbon-halogen bonds is a common challenge. In particular, selective oxidative addition of transition metals to alkyl halides rather than aryl halides is difficult due to unfavorable transition states and bond strengths. We describe a new approach that uses a single organic sulfide catalyst to activate both C(sp3) halides and arylboronic acids via a zwitterionic boron "ate" intermediate. This "ate" species undergoes a 1,2-metalate shift to afford Suzuki coupling products using benzyl chlorides and arylboronic acids. Various diaryl methane analogues can be prepared, including those with complex and biologically active motifs. The reactions proceed under transition-metal-free conditions, and C(sp2) halides, including aryl bromides and iodides, are unaffected. The orthogonal chemoselectivity is demonstrated in the streamlined synthesis of highly functionalized diaryl methane scaffolds using multi-halogenated substrates. Preliminary mechanistic experiments suggest both the sulfonium salt and the sulfur ylide are involved in the reaction, with the formation of sulfonium salt being the slowest step in the overall catalytic cycle.
He, Zhiqi,Song, Feifei,Sun, Huan,Huang, Yong
supporting information
p. 2693 - 2699
(2018/02/28)

Development of Versatile Sulfone Electrophiles for Suzuki-Miyaura Cross-Coupling Reactions
The development of fluorinated sulfone derivatives as versatile electrophiles for Suzuki-Miyaura cross-coupling reactions is described. Introducing electron-withdrawing groups on the aryl ring of the sulfone facilitates the Pd-catalyzed activation of C-SO2 bonds. Cross-coupling reactions with fluorinated sulfone electrophiles are reported, leading to a variety of multiply arylated products in good yields. The reactivity of this unusual electrophile is benchmarked versus common electrophiles and its use in iterative cross-couplings for concise synthesis of biologically active molecules is described.
Nambo, Masakazu,Keske, Eric C.,Rygus, Jason P. G.,Yim, Jacky C.-H.,Crudden, Cathleen M.
p. 1108 - 1112
(2017/08/09)

A Zinc Catalyzed C(sp3)?C(sp2) Suzuki–Miyaura Cross-Coupling Reaction Mediated by Aryl-Zincates
The Suzuki–Miyaura (SM) reaction is one of the most important methods for C?C bond formation in chemical synthesis. In this communication, we show for the first time that the low toxicity, inexpensive element zinc is able to catalyze SM reactions. The cross-coupling of benzyl bromides with aryl borates is catalyzed by ZnBr2, in a process that is free from added ligand, and is compatible with a range of functionalized benzyl bromides and arylboronic acid pinacol esters. Initial mechanistic investigations indicate that the selective in situ formation of triaryl zincates is crucial to promote selective cross-coupling reactivity, which is facilitated by employing an arylborate of optimal nucleophilicity.
Procter, Richard J.,Dunsford, Jay J.,Rushworth, Philip J.,Hulcoop, David G.,Layfield, Richard A.,Ingleson, Michael J.
p. 15889 - 15893
(2017/10/24)

One-pot borylation/Suzuki-Miyaura sp2-sp3 cross-coupling
We describe the first one-pot borylation/Suzuki-Miyaura sp2-sp3 cross-coupling between readily available aryl (pseudo)halides and activated alkyl chlorides. This method streamlines the synthesis of diaryl methanes, α-aryl carbonyls and allyl aryl compounds, substructures that are commonly found in life changing drug molecules.
Whitaker, Luke,Harb, Hassan Y.,Pulis, Alexander P.
p. 9364 - 9367
(2017/08/23)

Synthesis of Di- and Triarylmethanes through Palladium-Catalyzed Reductive Coupling of N -Tosylhydrazones and Aryl Bromides
A palladium-catalyzed reductive coupling between N-tosylhydrazones and aryl bromides has been developed. The reaction provides an efficient method for the synthesis of diarylmethanes and triarylmethanes via the formation of C(sp2)-C(sp3) single bonds. This new methodology for the synthesis of diarylmethanes and triarylmethanes is featured by the ready availability of the starting materials, mild reaction conditions, and the tolerance of wide range of functional groups. The reaction follows a pathway including palladium carbene formation, migratory insertion, and reduction of the alkylpalladium(II) intermediate.
Xia, Yamu,Hu, Fangdong,Xia, Ying,Liu, Zhenxing,Ye, Fei,Zhang, Yan,Wang, Jianbo
p. 1073 - 1086
(2017/02/24)

Cooperative Al-H Bond Activation in DIBAL-H: Catalytic Generation of an Alumenium-Ion-Like Lewis Acid for Hydrodefluorinative Friedel-Crafts Alkylation
The Ru-S bond in Ohki-Tatsumi complexes breaks oligomeric DIBAL-H structures into their more reactive monomer. That deaggregation is coupled to heterolytic Al-H bond activation at the Ru-S bond, formally splitting the Al-H linkage into hydride and an alumenium ion. The molecular structure of these Lewis pairs was established crystallographically, revealing an additional Ru-Al interaction next to the Ru-H and Al-S bonds. That bonding situation was further analyzed by quantum-chemical calculations and is best described as a three-center-two-electron (3c2e) donor-acceptor σ(Ru-H) → Al interaction. Despite the extra stabilization of the aluminum center by the interaction with both the sulfur atom and the Ru-H bond, the hydroalane adducts are found to be stronger Lewis acids and electrophiles than the free ruthenium catalyst and DIBAL-H in its different aggregation states. Hence, the DIBAL-H molecule and its Al-H bond are activated by the Ru-S bond, but these hydroalane adducts are not to be mistaken as sulfur-stabilized alumenium ions in a strict sense. The Ohki-Tatsumi complexes catalyze C(sp3)-F bond cleavage with DIBAL-H, and the catalytic setup is applied to hydrodefluorinative Friedel-Crafts alkylations. A broad range of CF3-substituted arenes is efficiently converted into unsymmetrical diarylmethanes with various arenes as nucleophiles. Computed fluoride-ion affinities (FIAs) of the hydroalane adducts as well as DIBAL-H in its aggregation states support this experimental finding.
Forster, Francis,Mets?nen, Toni T.,Irran, Elisabeth,Hrobárik, Peter,Oestreich, Martin
supporting information
p. 16334 - 16342
(2017/11/22)

An Efficient Synthetic Approach to trans-(NHC)2Pd(R)Br Type Complexes and Their Use in Suzuki–Miyaura Cross-Coupling Reactions
Mixed organohalidopalladium complexes of the type trans-(NHC)2Pd(R)Br were conveniently obtained from trans-(NHC)2PdBr2 type complexes by a ligand-substitution reaction. In particular, the trans-[1-(1S)-menthyl-4-(R1)-1,2,4-triazol-5-ylidene]2Pd(R2)Br [R1 = Et, R2 = CH2Ph (3a1); R1 = Et, R2 = o-OMeC6H4 (3a2); R1 = R2 = CH2Ph (3b1); R1 = CH2Ph, R2 = o-OMeC6H4 (3b2)] complexes were obtained from the corresponding palladium(II) precursor complexes, 2a,b, by reaction with the respective Grignard reagents, in good to excellent yields (74–93 %). Three of the four mixed organohalidopalladium complexes, 3a1,a2,b1, have been structurally characterized by single-crystal X-ray diffraction, which revealed the trans disposition of the NHC ligands around the palladium center. The use of these mixed organohalidopalladium complexes in the Suzuki–Miyaura cross-coupling reaction was established for all of the complexes, 3a1–b2, which yielded the desired cross-coupled products upon treatment with various ArB(OH)2 [Ar = 1-naphthyl, 4-(1,1′-biphenyl), 9-phenanthrenyl, 4-FC6H4, and 2,6-Me2C6H3] compounds, in the presence of NaOH as a base, in CH3CN, in three hours, under reflux conditions.
Kumar, Anuj,Prakasham,Gangwar, Manoj Kumar,Vishnoi, Pratap,Butcher, Raymond J.,Ghosh, Prasenjit
p. 2144 - 2154
(2017/04/21)

A Zwitterionic Palladium(II) Complex as a Precatalyst for Neat-Water-Mediated Cross-Coupling Reactions of Heteroaryl, Benzyl, and Aryl Acid Chlorides with Organoboron Reagents
The Suzuki–Miyaura cross-coupling (SMC) reactions of several heteroaryl chlorides, benzyl chlorides, and aryl acid chlorides with (hetero)arylboron reagents have been investigated in the presence of [Pd(HL1)(PPh3)Cl2] (I) [HL1 = 3-[(2,6-diisopropylphenyl)-1-imidazolio]-2-quinoxalinide] as catalyst and K2CO3 as base in neat water. The synthesis of the heterocycle-containing biaryls required the addition of 2 mol-% of a phosphine ligand (PPh3 or X-Phos). A combination of more than 115 substrates were screened and it was found that I is a versatile catalyst that can produce heterocycle-containing biaryls, diarylmethanes, and benzophenones in moderate-to-excellent yields.
Ramakrishna, Visannagari,Rani, Morla Jhansi,Reddy, Nareddula Dastagiri
p. 7238 - 7255
(2018/01/01)

N-Heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of benzyl carbamates with arylboronic acids
The Suzuki-Miyaura coupling of benzyl carbamates with arylboronic acids was achieved in an environmentally benign medium. Using water as the sole solvent, such transformation took place very well to give the desired diarylmethane derivatives in good to almost quantitative yields in the presence of a well-defined NHC-Pd(ii)-Im complex under mild conditions. It is worth noting here that this is the first example of benzyl carbamates used in coupling reaction, thus affording a new method for the formation of diarylmethanes by palladium-catalyzed C-O bond activation.
Wang, Xiao-Xia,Luo, Mao-Jun,Lu, Jian-Mei
p. 11438 - 11444
(2015/12/04)

N-heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of benzyl sulfonates with arylboronic acids
The first example of palladium-catalyzed Suzuki-Miyaura coupling between benzyl sulfonates and arylboronic acids was reported in this paper. In the presence of a well-defined, air-stable and easily available NHC-Pd(ii)-Im complex, all reactions worked well to give the desired products in good to almost quantitative yields under the optimal conditions. Electron-rich, -neutral, -poor and sterically-hindered substituents on both substrates are tolerated in such transformation, providing a convenient, efficient and alternative method for the synthesis of diarylmethanes.
Wang, Xiao-Xia,Xu, Bin-Bin,Song, Wen-Ting,Sun, Kai-Xin,Lu, Jian-Mei
p. 4925 - 4930
(2015/05/05)

Alternative approach toward the generation of benzylic zinc reagent: Direct oxidative addition of active zinc into the carbon-oxygen bond of benzyl mesylates
The use of highly active zinc, prepared by the Rieke method, for the direct preparation of benzylic zinc mesylate was investigated. The oxidative addition of highly active zinc to benzyl mesylate was easily completed under mild conditions. The resulting benzylic zinc mesylates were employed in subsequent cross-coupling reactions with a broad range of electrophiles, and the formation of the corresponding products was successful.
Jung, Hye-Soo,Kim, Seung-Hoi
p. 666 - 670
(2015/03/14)

Synthesis of diarylmethanes through palladium-catalyzed coupling of benzylic phosphates with arylsilanes
An efficient approach to the benzylation of arenes has been developed. The reactions described provide straightforward access to diarylmethanes through Pd-catalyzed coupling of benzylic phosphates with arylsilanes in good to excellent yields. The reaction tolerates a wide range of functionalities such as halide, alkoxyl, and nitro groups.
Zhang, Pengbo,Xu, Jian,Gao, Yuzhen,Li, Xueqin,Tang, Guo,Zhao, Yufen
p. 2928 - 2932
(2015/01/16)

Cyclometalated 2-phenylimidazole palladium carbene complexes in the catalytic Suzuki-Miyaura cross-coupling reaction
We present the syntheses of 12 cyclometalated palladium C-N 2-phenylimidazole carbene complexes with different N-1 groups as well as different substituents at the C-2 phenyl group of the cyclometalating imidazole. We investigated the influence of these substituents by comparing the catalytic performance of the complexes in the Suzuki-Miyaura cross-coupling reaction of aryl chlorides. We can show a strong dependence between the steric demand of the N-1 substituent of the cyclometalating imidazole and the catalytic activity in the cross-coupling reaction. The most active complex shows a wide substrate scope, where several aryl as well as benzyl chlorides could be coupled with different boronic acids in excellent yields using very low catalyst concentrations of 0.05 mol %.
Micksch, Maik,Tenne, Mario,Strassner, Thomas
p. 3966 - 3976
(2014/09/30)

Cu-Catalyzed Suzuki-Miyaura reactions of primary and secondary benzyl halides with arylboronates
A copper-catalyzed Suzuki-Miyaura coupling of benzyl halides with arylboronates is described. Varieties of primary benzyl halides as well as more challenging secondary benzyl halides with β hydrogens or steric hindrance could be successfully converted into the corresponding products. Thus it provides access to diarylmethanes, diarylethanes and triarylmethanes. This journal is the Partner Organisations 2014.
Sun, Yan-Yan,Yi, Jun,Lu, Xi,Zhang, Zhen-Qi,Xiao, Bin,Fu, Yao
p. 11060 - 11062
(2014/09/30)

Parallel and combinatorial liquid-phase synthesis of alkylbiphenyls using pentaerythritol support
Unfunctionalized alkylbiphenyls were fabricated by a parallel and combinatorial synthesis using pentaerythritol as a tetrapodal soluble support for a sulfonate-based traceless multifunctional linker system. Nickel N-heterocyclic carbene-catalyzed reactions of pentaerythritol tetrakis(biphenylsulfonate)s with primary alkylmagnesium bromides generated the alkylbiphenyl derivatives by desulfitative cleavage/cross-coupling of the C-S bond without any memory of the attachment on the support. Though the reactions were completed with sufficient yields in 12 h at room temperature, even with only 1.5 equiv of nucleophiles, they still retained the benefits of facile isolation observed in polymer-supported reactions.
Kim, Wang-Kyu,Jang, Jong-Hoon,Jo, Hyunjong,Park, Kwangyong
supporting information
p. 225 - 231
(2014/06/09)

Iron-catalyzed arylation of aromatic ketones and aldehydes mediated by organosilanes
A simple and efficient iron-catalyzed method for arylation of aromatic carbonyl compounds is reported. The use of 4-% FeCl3 or Fe(acac) 3 as the catalyst, in combination with a slight excess of chlorotrimethylsilane and triethylsilane, chlorination of benzylic ketones and aldehydes with subsequent Friedel-Crafts alkylation of arenes is achieved. Although the method is limited by the general constraints associated with Friedel-Crafts alkylation reactions, robust applications for the synthesis of pharmaceutical intermediates and so on can be envisioned. A robust one-pot, iron-catalyzed chlorination Friedel-Crafts alkylation reaction of benzylic carbonyl compounds, mediated by chlorotrimethylsilane and triethylsilane, has been developed to yield substituted diaryl and triaryl building blocks. Copyright
Savela, Risto,Majewski, Marcin,Leino, Reko
p. 4137 - 4147
(2014/07/08)

Palladium-catalyzed benzylation of arylboronic acids with N,N-ditosylbenzylamines
The palladium-catalyzed coupling of N,N-ditosylbenzylamines with arylboronic acids has been investigated, and the resulting diarylmethanes were obtained in high yields. Conversion of the amine to a N,N-ditosylimide group provided an efficient leaving group for the Pd-catalyzed benzylation of arylboronic acids.
Yoon, Sangeun,Hong, Myeng Chan,Rhee, Hakjune
p. 4206 - 4211
(2014/05/20)

Direct electrosynthesis of ketones from benzylic methylenes by electrooxidative C-H activation
Electrify your chemistry! Direct electrosynthesis of ketones from benzylic methylenes in an undivided cell was realized in moderate to good yields (see scheme). In this electrosynthesis, electrons instead of conventional oxidants and catalysts are employed to make the reaction environmentally benign. Moreover, the reaction intermediate radical was detected by ESR spectroscopy and the reaction mechanism was clarified.
Meng, Li,Su, Jihu,Zha, Zhenggen,Zhang, Li,Zhang, Zhenlei,Wang, Zhiyong
supporting information
p. 5542 - 5545
(2013/05/23)

N-Tosylhydrazine-mediated deoxygenative hydrogenation of aldehydes and ketones catalyzed by Pd/C
A mild and efficient method for the deoxygenative hydrogenation of aldehydes and ketones has been developed. The reaction is mediated by N-tosylhydrazine with H2 (1 atm) as the reductant and 10% Pd/C as the catalyst.
Zhou, Lei,Liu, Zhenxing,Liu, Yizhou,Zhang, Yan,Wang, Jianbo
p. 6083 - 6087
(2013/07/25)

Efficient synthesis of substituted styrenes and biaryls (or heteroaryls) with regioselective reactions of ortho -, meta -, and para-bromobenzyl bromide
Regio- and stereoselective reactions of ortho-, meta-, and para-bromobenzyl bromide under Stille and (or) Suzuki cross-coupling reactions are described that provided substituted styrene monomers and biaryls in two steps. By controlling the experimental conditions, the first coupling provided access to allylarene or diarylmethane intermediates, and the second reaction led to the desired styrenes and biaryls, substituted by a spacer arm in the ortho, meta or para position depending on the starting material. Georg Thieme Verlag Stuttgart · New York.
Anselmi, Elsa,Abarbri, Mohamed,Duchene, Alain,Langle-Lamande, Sandrine,Thibonnet, Jerome
experimental part
p. 2023 - 2040
(2012/09/05)

Direct arylation/alkylation/magnesiation of benzyl alcohols in the presence of grignard reagents via Ni-, Fe-, or Co-catalyzed sp3 C-O Bond activation
Direct application of benzyl alcohols (or their magnesium salts) as electrophiles in various reactions with Grignard reagents has been developed via transition metal-catalyzed sp3 C-O bond activation. Ni complex was found to be an efficient catalyst for the first direct cross coupling of benzyl alcohols with aryl/alkyl Grignard reagents, while Fe, Co, or Ni catalysts could promote the unprecedented conversion of benzyl alcohols to benzyl Grignard reagents in the presence of nhexylMgCl. These methods offer straightforward pathways to transform benzyl alcohols into a variety of functionalities.
Yu, Da-Gang,Wang, Xin,Zhu, Ru-Yi,Luo, Shuang,Zhang, Xiao-Bo,Wang, Bi-Qin,Wang, Lei,Shi, Zhang-Jie
p. 14638 - 14641
(2012/11/07)

Palladium(II) complexes of Y,C,Y-chelated phosphines: Synthesis, structure, and catalytic activity in Suzuki-Miyaura reaction
The phosphines L1PPh2 (1) and L2PPh 2 (2) containing different Y,C,Y-chelating ligands, L1 = 2,6-(tBuOCH2)2C6H3 - and L2 = 2,6-(Me2NCH2) 2C6H3-, were treated with PdCl 2 and di-Aμ-chloro-bis[2-[(N,N-dimethylamino)methyl]phenyl- C,N]-dipalladium(II) and yielded complexes trans-{[2,6-(tBuOCH 2)2C6H3]PPh2} 2PdCl2 (3), {[2,6-(Me2NCH2) 2C6H3]PPh2} PdCl2 (4), {[2,6-(tBuOCH2)2C6H 3]PPh2}Pd(Cl)[2-(Me2NCH2)C 6H4] (5) and {[2,6-(Me2NCH2) 2C6H3]PPh2}Pd(Cl)[2-(Me 2NCH2)C6H4] (6) as the result of different ability of starting phosphines 1 and 2 to complex PdCl2. Compounds 3-6 were characterized by 1H, 13C, 31P NMR spectroscopy and ESI-MS. The molecular structures of 3,4 and 6 were also determined by X-ray diffraction analysis. The catalytic activity of complexes 3-6 was evaluated in the Suzuki-Miyaura cross-coupling reaction.
Reznicek, Tomas,Dostal, Libor,Ruzicka, Ales,Kulhanek, Jiri,Bures, Filip,Jambor, Roman
experimental part
p. 173 - 179
(2012/04/23)

Synthesis and characterization of imine-palladacycles containing imidate "pseudohalide" ligands: Efficient Suzuki-Miyaura cross-coupling precatalysts and their activation to give Pd0Ln species (L = Phosphine)
Dinuclear palladacyclic complexes [{Pd(C^N)(μ-NCO)} 2] (C^N = N-phenylbenzaldimine, Phbz) containing asymmetric imidato units (-NCO- = succinimidate (succ; 1), phthalimidate (phthal; 2), maleimidate (mal; 3), 2,3-dibromomaleimidate (2,3-diBrmal; 4), glutarimidate (glut; 5)) have been readily prepared by reaction between the di-μ-acetate precursor and cyclic imide ligands in a 1:2 molar ratio. Base treatment of the less acidic ligands 2-oxazolidone and δ-valerolactame with KOH/MeOH was required to give analogous -NCO- bridged complexes (6 and 7). Reactions of the dinuclear complexes with tertiary phosphines provide novel mononuclear N-bonded imidate derivatives of the general formula [Pd(Phbz)(imidate)(PR3)] (R = Ph (a), 4-F-C6H4 (b), 4-MeO-C6H4 (c), CH2CH2CN (d)). The application of these novel palladacyclic complexes as precatalysts for the Suzuki-Miyaura cross-coupling reactions of both aryl and benzyl bromides with phenylboronic acid has been examined. The acetate adducts [Pd(Phbz)(CH 3COO)(PR3)] (8a,c) were prepared to assess the role of imidate ligands in catalyst performance. The mononuclear imidate derivatives possess greater activity than the parent dinuclear complexes, exhibiting comparable performance in the cross-coupling of benzyl bromide with arylboronic acids to the best examples reported in the literature. The mononuclear imidate derivatives give a common Pd0Ln intermediate, as inferred by the release of the organic fragment (first reductive elimination product). Catalyst activation occurs by reaction of phenylboronic acid with the palladacycle in the absence of exogenous base (as shown by GC-MS and ESI-MS), with implications for the reliable comparison of catalyst performance across a series of related precatalysts (e.g., how catalyst/reagents are mixed and what is their order of addition). The single-crystal X-ray structures of compounds 4, 7, 1d, 3c, and 8a have been determined.
Serrano, Jose Luis,Garcia, Luis,Perez, Jose,Perez, Eduardo,Garcia, Joaquin,Sanchez, Gregorio,Sehnal, Petr,De Ornellas, Sara,Williams, Thomas J.,Fairlamb, Ian J. S.
experimental part
p. 5095 - 5109
(2011/11/14)

InBr3-catalyzed deoxygenation of carboxylic acids with a hydrosilane: Reductive conversion of aliphatic or aromatic carboxylic acids to primary alcohols or diphenylmethanes
A simple and practical procedure for the direct reduction of aliphatic carboxylic acids with a variety of functional groups to a primary alcohol using the mild reducing reagent tetramethyldisiloxane (TMDS), in the presence of a catalytic amount of InBr3 has been developed. This simple reducing system, when used together with a hydrosilane, allows the preparation of the diphenylmethane derivative directly from an aromatic carboxylic acid and an aromatic compound. Copyright
Sakai, Norio,Kawana, Keita,Ikeda, Reiko,Nakaike, Yumi,Konakahara, Takeo
experimental part
p. 3178 - 3183
(2011/06/28)

Microwave-assisted nafion-H catalyzed friedel-crafts type reaction of aromatic aldehydes with arenes: Synthesis of triarylmethanes
A new solid acid Nafion-H, a perfluorinated sulfonic acid resin, catalyzed microwave-assisted synthesis of triarylmethanes is described. Various benzaldehydes react readily with arenes to provide the corresponding triarylmethanes in good to excellent yields. The reactions were carried out under solvent free conditions under microwave irradiation in a pressure vessel. The solvent free microwave irradiation methods appears to be an environmentally friendly synthetic protocol providing products in significantly shorter reaction times over traditional heating methods carried out in a pressure tube.
Prakash, Surya G. K.,Fogassy, Gabriella,Olah, George A.
experimental part
p. 155 - 159
(2011/01/04)

Extremely efficient cross-coupling of benzylic halides with aryltitanium tris(isopropoxide) catalyzed by low loadings of a simple palladium(II) acctate/Tris(p-tolyl)phosphine system
Highly efficient coupling reactions of benzylic bromides or chlorides with aryltitanium tris(isopropoxide) [ArTi(O-i-Pr)3] catalyzed by a simple palladium(II) Acctate/tris(p-tolyl)phosphine [Pd(OAc)2/ P(p-tolyl)3] system are reported. The coupling reactions proceed in general at room temperature employing low catalyst loadings of 0.02 to 0.2 mol%, affording coupling products in excellent yields of up to 99%. For benzylic bromides bearing strong electronwithdrawing cyano (CN) or trifluoromethyl (CF 3) substituents, the reactions require a higher catalyst loading of 1 mol%, or the reactions are carried out at 60°C. The catalytic system also tolerates (1-bromoethyl)benzene bearing β-hydrogen atoms while using a catalyst loading of 1 mol% to afford the coupling product in a 70% yield.
Chen, Chi-Ren,Zhou, Shuangliu,Biradar, Deepak Baburao,Gau, Han-Mou
experimental part
p. 1718 - 1727
(2010/09/18)

A metal-free catalytic system for the oxidation of benzylic methylenes and primary amines under solvent-free conditions
Iodine-pyridine-tert-butylhydroperoxide is developed as a green and efficient catalytic system for the oxidation of benzylic methylenes to ketones and primary amines to nitriles. The reaction conditions are quite mild and environmentally benign, no transition metals, organic solvents or hazard reagents being needed. The oxidation of benzylic methylenes gave the corresponding ketones in excellent yields with complete chemoselectivity, while the oxidation of primary amines was complete in several minutes, affording various nitriles in moderate to good yields.
Zhang, Jintang,Wang, Zhentao,Wang, Ye,Wan, Changfeng,Zheng, Xiaoqi,Wang, Zhiyong
supporting information; scheme or table
p. 1973 - 1978
(2010/06/15)