- Mechanistic study on benzylic oxidations catalyzed by bismuth(III) salts: X-ray structures of two bismuth-picolinate complexes
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We report studies that are consistent with benzylic oxidation reactions catalyzed using bismuth(III) salts proceeding via a radical mechanism. Additionally, X-ray structures of two potential bismuth-picolinate complex intermediates are reported.
- Callens, Emmanuel,Burton, Andrew J.,White, Andrew J.P.,Barrett, Anthony G.M.
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Read Online
- Nickel-Catalyzed C-Br/C-H Bis-phenylation of Methyl 4-Bromocrotonate: A Stereoselective Entry to Methyl (E)-3,4-Diphenylbut-2-enoate
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A method for C-Br/C-H bis-phenylation of methyl 4-bromocrotonate via nickel-catalyzed cross-coupling reaction has been developed. This protocol involves commercially available catalyst components and furnishes a suitable doubly phenylated building block.
- Funicello, Maria,Chiummiento, Lucia,Lupattelli, Paolo,Tramutola, Francesco
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Read Online
- A Simple Synthesis of 1,3-Diphenylpropene
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A simple approach to the synthesis of 1,3-diphenylpropene isomers was developed based on Fe(acac)3-catalyzed cross-coupling of (E)- and (Z)-1,3-dichloropropenes with phenylmagnesium bromide.
- Shakhmaev,Sunagatullina, A. Sh.,Vasilyeva,Zorin
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Read Online
- Vinylation of Benzylic Amines via C-N Bond Functionalization of Benzylic Pyridinium Salts
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Cross-couplings of benzylic pyridinium salts and vinylboronic acids or esters have been developed. Via benzylic pyridinium intermediates, benzylic amines can be engaged in these cross-couplings through C-N bond functionalization. This method boasts mild reaction conditions and excellent tolerance for heteroaryl substituents and a range of functional groups.
- Guan, Weiye,Liao, Jennie,Watson, Mary P.
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Read Online
- Direct and Unified Access to Carbon Radicals from Aliphatic Alcohols by Cost-Efficient Titanium-Mediated Homolytic C?OH Bond Cleavage
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Low-valent Ti-mediated homolytic C?O bond cleavage offers unified access to carbon radicals from ubiquitous non-activated tertiary, secondary, and even primary alcohols. In contrast to the representative Ti reagents, which were ineffective for this purpos
- Suga, Takuya,Takahashi, Yuuki,Miki, Chinatsu,Ukaji, Yutaka
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- Palladacycle-Catalyzed Regioselective Heck Reaction Using Diaryliodonium Triflates and Aryl Iodides
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We describe a P-containing palladacycle-catalyzed regioselective Heck reaction of 2,3-dihydrofuran with diaryliodonium salts and aryl iodides to afford 2-aryl-2,5-dihydrofurans and 2-aryl-2,3-dihydrofurans, respectively, in good yields. Mechanistic studie
- Hou, Cheng,Lei, Lu,Liang, Cui,Mo, Dong-Liang,Wang, Zhi-Xin,Zou, Pei-Sen
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supporting information
p. 663 - 667
(2022/01/28)
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- Nickel-Catalyzed Electrochemical C(sp3)?C(sp2) Cross-Coupling Reactions of Benzyl Trifluoroborate and Organic Halides**
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Reported here is the redox neutral electrochemical C(sp2)?C(sp3) cross-coupling reaction of bench-stable aryl halides or β-bromostyrene (electrophiles) and benzylic trifluoroborates (nucleophiles) using nonprecious, bench-stable NiCl2?glyme/polypyridine catalysts in an undivided cell configuration under ambient conditions. The broad reaction scope and good yields of the Ni-catalyzed electrochemical coupling reactions were confirmed by 50 examples of aryl/β-styrenyl chloride/bromide and benzylic trifluoroborates. Potential applications were demonstrated by electrosynthesis and late-stage functionalization of pharmaceuticals and natural amino acid modification, and three reactions were run on gram-scale in a flow-cell electrolyzer. The electrochemical C?C cross-coupling reactions proceed through an unconventional radical transmetalation mechanism. This method is highly productive and expected to find wide-spread applications in organic synthesis.
- Luo, Jian,Hu, Bo,Wu, Wenda,Hu, Maowei,Liu, T. Leo
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supporting information
p. 6107 - 6116
(2021/02/01)
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- Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source
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Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp3)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.
- Biswas, Nandita,Srimani, Dipankar
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p. 10544 - 10554
(2021/07/31)
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- Method for synthesizing 1, 2-disubstituted olefin through reaction of terminal group olefin and sulfoxide
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The invention discloses a method for synthesizing 1, 2-disubstituted olefin by reaction of terminal olefin and sulfoxide. According to the method, terminal olefin with sulfoxide make reaction in one pot in the presence of ferric salt and hydrogen peroxide to generate the 1, 2-disubstituted olefin. sulfoxide is simultaneously used as a hydrocarbylation reagent and a solvent of olefin, and a reaction product is 1, 2-disubstituted olefin of which a terminal carbon atom in terminal olefin is coupled with a sulfoxide alkyl group, so that an olefin carbon chain is increased; the reaction conditionsare mild, the selectivity is high, the yield is high, and industrial production is facilitated.
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Paragraph 0053-0054; 0057-0062; 0080
(2021/02/10)
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- Method for synthesizing alkyl olefin through coupling of double-bond carbon-hydrogen bond and saturated carbon-hydrogen bond
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The invention discloses a method for synthesizing alkyl olefin through coupling of a double-bond carbon-hydrogen bond and a saturated carbon-hydrogen bond. According to to the method, one-pot reactionis implemented on olefin and sulfoxide in the presence of ferric salt and hydrogen peroxide to generate alkyl olefin; in the method, sulfoxide is simultaneously used as a hydrocarbylation reagent anda solvent of olefin, and a reaction product is alkyl olefin from sulfoxide alkyl coupled with olefin carbon atoms, so that an olefin carbon chain is increased; the reaction conditions are mild, the selectivity is good, the yield is high, and industrial production is facilitated.
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Paragraph 0074-0077; 0103
(2021/02/10)
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- Pd-Catalyzed Nazarov-Type Cyclization: Application in the Total Synthesis of β-Diasarone and Other Complex Cyclopentanoids
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We describe the palladium-catalyzed Nazarov-type cyclization of easily accessible (hetero)arylallyl acetates to pentannulated (hetero)arenes. This method provides ready access to various types of bi-, tri-, tetra-, and pentacyclic cyclopentanoids under ne
- Bankar, Siddheshwar K.,Ramasastry, S. S. V.,Singh, Bara
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supporting information
(2022/02/05)
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- Palladium-Catalyzed Regioselective and Stereospecific Ring-Opening Suzuki-Miyaura Arylative Cross-Coupling of 2-Arylazetidines with Arylboronic Acids
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We have developed a palladium-catalyzed regioselective and enantiospecific ring-opening Suzuki–Miyaura arylative cross-coupling of N-tosyl-2-arylazetidines to give enantioenriched 3,3-diarylpropylamines. This reaction represents an example of transition-metal-catalyzed ring-opening cross-coupling using azetidines as a non-classical alkyl electrophile. Density functional theory rationalized the mechanism of the full catalytic cycle, which consists of the selectivity-determining ring opening of the azetidine, reaction with water, rate-determining transmetalation, and reductive elimination. Transition states of the selectivity-determining ring-opening step were systematically determined by the multi-component artificial force induced reaction (MC-AFIR) method to explain the regioselectivity of the reaction. (Figure presented.).
- Takeda, Youhei,Toyoda, Kazuya,Sameera,Tohnai, Norimitsu,Minakata, Satoshi
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p. 2796 - 2805
(2021/04/15)
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- NHC-Iridium-Catalyzed Deoxygenative Coupling of Primary Alcohols Producing Alkanes Directly: Synergistic Hydrogenation with Sodium Formate Generated in Situ
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The direct conversion of alcohols into long-chain alkanes is an attractive but extremely challenging approach for biomass upgrading. Here, we describe the highly selective deoxygenative coupling of aryl ethanols with primary alcohols to produce alkanes, using a bis-N-heterocyclic carbene iridium (bis-NHC-Ir) complex as the catalyst. Up to quantitative yields and selectivity with a broad substrate scope are attained in both homo- and cross-coupling reactions. Mechanistic studies reveal that the further synergistic hydrogenation of the alkene intermediates by the formate generated in situ in the presence of bis-NHC-Ir is crucial for alkane production.
- Lu, Zeye,Zheng, Qingshu,Yang, Siqi,Qian, Chun,Shen, Yajing,Tu, Tao
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p. 10796 - 10801
(2021/09/08)
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- Electrochemically Enabled, Nickel-Catalyzed Dehydroxylative Cross-Coupling of Alcohols with Aryl Halides
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As alcohols are ubiquitous throughout chemical science, this functional group represents a highly attractive starting material for forging new C-C bonds. Here, we demonstrate that the combination of anodic preparation of the alkoxy triphenylphosphonium ion and nickel-catalyzed cathodic reductive cross-coupling provides an efficient method to construct C(sp2)-C(sp3) bonds, in which free alcohols and aryl bromides - both readily available chemicals - can be directly used as coupling partners. This nickel-catalyzed paired electrolysis reaction features a broad substrate scope bearing a wide gamut of functionalities, which was illustrated by the late-stage arylation of several structurally complex natural products and pharmaceuticals.
- Li, Zijian,Sun, Wenxuan,Wang, Xianxu,Li, Luyang,Zhang, Yong,Li, Chao
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supporting information
p. 3536 - 3543
(2021/03/08)
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- Deoxygenative coupling of 2-aryl-ethanols catalyzed by unsymmetrical pyrazolyl-pyridinyl-triazole ruthenium
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A pyrazolyl-pyridinyl-triazole Ru complex was synthesized from unsymmetrical pyrazolyl-pyridinyl-triazole (PPT) skeleton ligand and characterized through X-ray crystallography. The corresponding heterogeneous pyrazolyl-pyridinyl-triazole Ru complexes on γ
- Cao, Fei,Duan, Zheng-Chao,Zhu, Haiyan,Wang, Dawei
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- Method for preparing alkane through coupling of primary alcohol catalyzed by N-heterocyclic carbene metal compound
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The invention belongs to the technical field of transition metal catalysis and coupling reaction of biomass alcohol, and particularly relates to a method for preparing alkane in one step through self-coupling and cross-coupling of primary alcohol catalyzed by an N-heterocyclic carbene metal compound. The invention firstly provides a catalyst, namely a homogeneous N-heterocyclic carbene metal compound, for preparing alkane through primary alcohol coupling. The method comprises the following steps: by taking primary alcohol as a reaction raw material, tert-butyl alcohol salt of alkali metal, hydroxide and other strong alkalis as alkalis, the N-heterocyclic carbene metal compound as a catalyst and tertiary alcohol, benzene analogue or long-chain alkane as a solvent, reacting at 80-200 DEG C for 4-24 hours to obtain a corresponding alkane product. Compared with the prior art, the method disclosed by the invention has the advantages that the cheap and easily available biomass alcohol can be used as the starting raw material, the use of toxic phosphine-containing ligands with poor stability is avoided, the reaction selectivity and the yield can be quantified, the operation is simple and convenient, different high-purity alkane products can be obtained only through simple post-treatment, and the method is suitable for industrial amplification and application.
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Paragraph 0079-0100
(2021/08/19)
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- Construction of 5H-Dibenzo[c,e]azepine Framework from Dibenzothiophene Dioxides and N-Benzylimines through SNAr Reactions
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Treatment of a mixture of dibenzothiophene dioxides and benzaldehyde N-benzylimines with potassium hexamethyldisilazide induces sequential intermolecular and intramolecular SNAr reactions to eventually form the corresponding 5H-dibenzo[c,e]azep
- Furukawa, Tomoki,Kaga, Atsushi,Saito, Hayate,Yanagi, Tomoyuki,Yorimitsu, Hideki
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- Nickel-Catalyzed Reductive Csp2-Csp3Cross Coupling Using Phosphonium Salts
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A nickel-catalyzed reductive cross coupling with phosphonium salts and allylic C(sp3)-O bond electrophiles, which granted direct construction of the C(sp2)-C(sp3) bond, is successfully developed. The protocol features broad substrate scope, high-functional-group tolerance, and heterocycle compatibility. Notably, the much more challenging reductive cross coupling with heterocyclic thiazolylphosphonium salts has also been accomplished for the first time.
- Liang, Hongze,Lu, Xinyao,Luo, Yunjie,Man, Xi,Mou, Zehuai,Wang, Huifei,Wang, Yuting,Yang, Mengwan
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p. 8183 - 8188
(2021/11/13)
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- Nickel-Catalyzed Arylation of C(sp3)-O Bonds in Allylic Alkyl Ethers with Organoboron Compounds
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A nickel-catalyzed cross-coupling of allylic alkyl ethers with organoboron compounds through the cleavage of the inert C(sp3)-O(alkyl) bonds is described. Several types of allylic alkyl ethers can be coupled with various boronic acids or their derivatives to give the corresponding products in good to excellent yields with wide functional group tolerance and excellent regioselectivity. The gram-scale reaction and late-stage modification of biologically active compounds further prove the practicality of this synthetic method.
- Li, Xiaowei,Li, Yuxiu,Zhang, Zhong,Shi, Xiaolin,Liu, Ruihua,Wang, Zemin,Li, Xiangqian,Shi, Dayong
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p. 6612 - 6616
(2021/09/02)
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- Dehydrative allylation of P-H species under metal-free conditions
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An environmentally benign protocol for C-P bond construction was developed under metal- and solvent-free conditions. In the presence of B(C6F5)3, wide-spectrum P-H species, including dialkylphosphite, hypophosphite ester,
- Yang, Xiaobo,Li, Bowen,Xing, Huicong,Qiu, Ju,Loh, Teck-Peng,Xie, Peizhong
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supporting information
p. 1633 - 1637
(2021/03/09)
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- METHOD FOR PRODUCING ARENE COMPOUNDS AND ARENE COMPOUNDS PRODUCED BY THE SAME
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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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Paragraph 0032
(2021/06/26)
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- Boron-catalyzed dehydrative allylation of 1,3-diketones and β-ketone esters with 1,3-diarylallyl alcohols in water
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A metal-free catalytic allylation with atom economy and green environment friendly was developed. Allylic alcohols could be directly dehydrated in water by B(C6F5)3, without using any base additives. The reaction can afford the corresponding monoallylated product in moderate to high yield and has been performed on a gram-scale, and a quaternary carbon center can be constructed for the active methine compounds of 1,3-diketones or β-ketone esters in this process. The product can be further converted, such as the synthesis of tetra-substituted pyrazole compounds, or 1,4-dienes and functionalized dihydropyrans.
- Zhang, Guo-Min,Zhang, Hua,Wang, Bei,Wang, Ji-Yu
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p. 17025 - 17031
(2021/05/25)
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- Electro-mediated PhotoRedox Catalysis for Selective C(sp3)–O Cleavages of Phosphinated Alcohols to Carbanions
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We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp3)?O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E-selective and can be made Z-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation, and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for an intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp3)?O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions tolerate aryl chlorides/bromides and do not give rise to Birch-type reductions.
- Barham, Joshua P.,K?nig, Burkhard,Karl, Tobias A.,Reiter, Sebastian,Tian, Xianhai,Yakubov, Shahboz,de Vivie-Riedle, Regina
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p. 20817 - 20825
(2021/08/18)
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- Base-promoted one-pot synthesis of pyridine derivatives via aromatic alkyne annulation using benzamides as nitrogen source
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In the presence of Cs2CO3, the first simple, efficient, and one-pot procedure for the synthesis of 3,5-diaryl pyridines via a variety of aromatic terminal alkynes with benzamides as the nitrogen source in sulfolane is described. The formation of pyridine derivatives accompanies the outcome of 1,3-diaryl propenes, which are also useful intermediates in organic synthesis. Thus, pyridine ring results from a formal [2+2+1+1] cyclocondensation of three alkynes with benzamides, and one of the alkynes provides one carbon, whilst benzamides provide a nitrogen source only. A new transformation of alkynes as well as new utility of benzamide are found in this work.
- Ashiq, Muhammad Naeem,Hua, Ruimao,Iqbal, Muhammad Asif,Mehmood, Hina
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supporting information
(2021/11/08)
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- Nickel-catalyzed cross-electrophile coupling of aryl chlorides with allylic alcohols
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Nickel-catalyzed cross-electrophile coupling of aryl chlorides with allylic alcohols proceeds readily under mild conditions in the presence of zinc powder and MgCl2to produce allylarenes in 25-92% yields. The reaction shows high regioselectivit
- Yu, Hang,Wang, Zhong-Xia
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p. 9723 - 9731
(2021/12/01)
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- METHODS OF ARENE ALKENYLATION
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The present disclosure provides for a rhodium-catalyzed oxidative arene alkenylation from arenes and styrenes to prepare stilbene and stilbene derivatives. For example, the present disclosure provides for method of making arenes or substituted arenes, in particular stilbene and stilbene derivatives, from a reaction of an optionally substituted arene and/or optionally substituted styrene. The reaction includes a Rh catalyst or Rh pre-catalyst material and an oxidant, where the Rh catalyst or Rh catalyst formed Rh pre-catalyst material selectively functionalizes CH bond on the arene compound (e.g., benzene or substituted benzene).
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Page/Page column 18; 42; 51-52
(2021/11/26)
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- Decarbonylative Olefination of Aldehydes to Alkenes
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New atom-economical alternatives to Wittig chemistry are needed to construct olefins from carbonyl compounds, but none have been developed to-date. Here we report an atom-economical olefination of carbonyls via aldol-decarbonylative coupling of aldehydes using robust and recyclable supported Pd catalysts, producing only CO and H2O as waste. The reaction affords homocoupling of aliphatic aldehydes, as well as heterocoupling of aliphatic and aromatic ones. Computations provide insight into the selectivity and thermodynamics of the reaction. The tandem aldol-decarbonylation reaction opens the door to exploration of new carbonyl reactivity to construct olefins.
- Ainembabazi, Diana,Reid, Christopher,Chen, Amanda,An, Nan,Kostal, Jakub,Voutchkova-Kostal, Adelina
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supporting information
p. 696 - 699
(2020/01/31)
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- Nickel-Catalyzed Alkylation or Reduction of Allylic Alcohols with Alkyl Grignard Reagents
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By choosing different phosphine ligands, nickel-catalyzed selective alkylation and reduction of allylic alcohols with alkyl Grignard reagents were performed. The reaction using Ni(dppe)Cl2 as the catalyst resulted in the cross-coupling of allylic alcohols with primary alkyl Grignard reagents and cyclopropylmagnesium bromide. The reaction catalyzed by the combination of Ni(PCy3)2Cl2 and dcype led to the reduction of allylic alcohols. Secondary alkyl Grignard reagents except cyclopropylmagnesium bromide always led to reduction of allylic alcohols using either Ni(dppe)Cl2 or Ni(PCy3)2Cl2/dcype as the catalyst. In the reductive reaction β-H-containing alkyl Grignard reagents were required.
- Yang, Bo,Wang, Zhong-Xia
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p. 4772 - 4784
(2020/05/01)
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- C–C Cross-Coupling Reactions of Organosilanes with Terminal Alkenes and Allylic Acetates Using PdII Catalyst Supported on Starch Coated Magnetic Nanoparticles
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Starch coated magnetic nanoparticles supported palladium catalyst has been explored to perform C–C cross coupling reactions, such as oxidative Heck coupling and Tsuji–Trost allylic coupling using organosilicon compounds as one of the coupling partners. The biopolymer coated magnetic catalyst was very easy to recover magnetically and was efficiently recycled in the subsequent batches. All the reactions were performed in air and thus the necessity of air and moisture free reaction condition is avoided. The present protocols show wide substrate scope and good yields of the products.
- Patra, Debabrata,Panja, Subir,Saha, Amit
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p. 878 - 883
(2020/02/13)
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- Multifunctional chiral aminophosphines for enantiodivergent catalysis in a palladium-catalyzed allylic alkylation reaction
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Trifunctional MAP-based chiral phosphines were tested as new ligands in a Pd-catalyzed asymmetric allylic alkylation, demonstrating fast and enantiodivergent catalysis. The palladium complexes of representative ligands by X-ray analysis revealed a novel mode of P,N-coordination of the ligand to the palladium center, which may contribute to switching the sense of the asymmetric induction via combined steric and tunable H-bonding interactions between the metal complex and the substrates.
- Eliseenko, Sviatoslav S.,Bhadbhade, Mohan,Liu, Fei
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p. 1311 - 1323
(2020/08/07)
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- Analyses of the Structural and Electronic Properties of NHCs with Bicyclic Architectures
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Quantification of the steric and electronic properties of ligands is an important task for the development of highly effective chemical transformations when using a metal complex as a catalyst. In this study, we used silver and iridium complexes to perform systematic analyses to quantify the steric and electronic properties of original NHCs, which we refer to as DHASI and BCPSI. In addition to two silver chloride complexes that we previously reported, two novel BCPSIiPrAgCl and BCPSICyAgCl complexes were prepared and used for XRD studies to quantify the steric properties via use of a method referred to as the percent buried volume (%VBur). We then synthesized 6 IrCl(CO)2(HNC) complexes to calculate the TEP values, and the results indicated that the influences of two different core bicyclic motifs were somewhat unclear, while the influences of different N-substituents were readily apparent. Finally, the original NHCs were applied to a copper catalyzed allylic arylation of cinnamyl bromide with PhMgBr. The regioselectivity of the substitutions suggested that the steric environments existing at relatively long distances from the bound copper also exerted a considerable amount of influence over the catalytic properties.
- Ando, Shin,Otsuka, Mio,Ishizuka, Tadao
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p. 3839 - 3848
(2020/11/13)
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- Chemoselective Hydrosilylation of the α,β-Site Double Bond in α,β- And α,β,γ,δ-Unsaturated Ketones Catalyzed by Macrosteric Borane Promoted by Hexafluoro-2-propanol
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The B(C6F5)3-catalyzed chemoselective hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones into the corresponding non-symmetric ketones in mild reaction conditions is developed. Nearly 55 substrates including those bearing reducible functional groups such as alkynyl, alkenyl, cyano, and aromatic heterocycles are chemoselectively hydrosilylated in good to excellent yields. Isotope-labeling studies revealed that hexafluoro-2-propanol also served as a hydrogen source in the process.
- Zhan, Xiao-Yu,Zhang, Hua,Dong, Yu,Yang, Jian,He, Shuai,Shi, Zhi-Chuan,Tang, Lei,Wang, Ji-Yu
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p. 6578 - 6592
(2020/07/17)
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- A photocatalyst-free photo-induced denitroalkylation of β-nitrostyrenes with 4-alkyl substituted Hantzsch esters at room temperature
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A photocatalyst-free stereoselectively photo-induced strategy for the denitroalkylation of β-nitrostyrenes using 4-alkyl substituted Hantzsch esters as the alkyl source under xenon lamp irradiation is developed. The reaction proceeds at room temperature and affords the corresponding products in moderate to excellent yields. The oxidant di-t-butyl peroxide serves as an efficient radical initiator under irradiation of a Xenon lamp, initiating alkyl radicals from the 4-alkyl substituted Hantzsch esters.
- Duan, Chunying,Hao, Xinyu,Jin, Kun,Li, Yaming,Wang, Jiaao,Zhang, Rong,Zhang, Siyu
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- In Situ Ring-Closing Strategy for Direct Synthesis of N-Heterocyclic Carbene Nickel Complexes and Their Application in Coupling of Allylic Alcohols with Aryl Boronic Acids
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A in situ ring-closing strategy was developed for the synthesis of N-heterocyclic carbene nickel complexes. The process was carried out in air, and did not require solvent purification. The resulting nickel complexes were investigated as catalysts for the coupling of allylic alcohols with aryl boronic acids. A wide range of allylic substrates and aryl acids proved to be applicable to this catalytic system. Control experiments suggest that the Ni(0) may be the true active species in the coupling reactions. (Figure presented.).
- Wang, Yu-Bin,Liu, Bin-Yuan,Bu, Qingqing,Dai, Bin,Liu, Ning
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p. 2930 - 2940
(2020/06/17)
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- Synthesis of Stilbenes by Rhodium-Catalyzed Aerobic Alkenylation of Arenes via C-H Activation
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Arene alkenylation is commonly achieved by late transition metal-mediated C(sp2)-C(sp2) cross-coupling, but this strategy typically requires prefunctionalized substrates (e.g., with halides or pseudohalides) and/or the presence of a directing group on the arene. Transition metal-mediated arene C-H activation and alkenylation offers an alternative method to functionalize arene substrates. Herein, we report a rhodium-catalyzed oxidative arene alkenylation from arenes and styrenes to prepare stilbene and stilbene derivatives. The reaction is successful with several functional groups on both the arene and the olefin including fluoride, chloride, trifluoromethyl, ester, nitro, acetate, cyanide, and ether groups. Reactions of monosubstituted arenes are selective for alkenylation at the meta and para positions, generally with approximately 2:1 selectivity, respectively. Resveratrol and (E)-1,2,3-trimethoxy-5-(4-methoxystyryl)benzene (DMU-212) are synthesized by this single-step approach in high yield. Comparison with palladium catalysis showed that rhodium catalysis is more selective for meta-functionalization for monosubstituted arenes and that the Rh catalysis has better tolerance of halogen groups.
- Jia, Xiaofan,Frye, Lucas I.,Zhu, Weihao,Gu, Shunyan,Gunnoe, T. Brent
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supporting information
p. 10534 - 10543
(2020/06/08)
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- Palladium-catalyzed reaction of γ-silylated allyl acetates proceeding through 1,2-shift of a substituent on silicon
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The palladium-catalyzed reaction of γ-silylated allyl acetates with water in the presence of CsF induces a previously unprecedented 1,2-shift of a substituent on silicon to produce allylsilanes in situ. The catalytic activity of the palladium increased when using an electron-poor phosphine ligand possessing fluorinated substituents. Further investigation of the reaction revealed that the approximate order of the migratory aptitude of groups from silicon was PhC≡C, allyl > Bn > Ph, vinyl > alkyl (Me, Et). A density functional theory study was employed to explore the reaction mechanism. Finally, the Hosomi–Sakurai-type allylation of aldehydes with in situ-generated α,γ-disubstituted allylsilanes was also investigated.
- Horino, Yoshikazu,Ishibashi, Mayo,Nakasai, Kosuke,Korenaga, Toshinobu
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- Synthetic method of ethyl 2,4,6-triphenylnicotinate
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The invention discloses a synthetic method of ethyl 2,4,6-triphenylnicotinate. The method comprises the following steps of: reacting beta-enamine ester as shown in a formula I and 1,3-diphenyl propylene as shown in a formula II which are used as raw mater
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Paragraph 0014; 0015
(2020/01/08)
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- Visible Light-Driven, Room Temperature Heck-Type Reaction of Alkyl Halides with Styrene Derivatives Catalyzed by B12 Complex
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A visible light driven Heck-type coupling reaction of alkyl halides with styrene and its derivatives catalyzed by the cobalamin derivative (B12) with the [Ru(bpy)3]Cl2 photosensitizer at room temperature is reported. The catalytic efficiencies of the B12 catalyst were compared to that of other cobalt complexes such as cobaloxime. Various control experiments supported a radical-based mechanism similar to those for typical B12 model reactions. A unique coupling reaction combined with 1,2-migration of the functional group is also reported. Mild reaction conditions using an environmentally benign cobalt catalyst derived from the natural B12 provided a practical protocol for the synthetic organic chemistry of the B12 catalyzed reaction system. (Figure presented.).
- Chen, Li,Hisaeda, Yoshio,Shimakoshi, Hisashi
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p. 2877 - 2884
(2019/04/03)
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- Asmic Isocyanide-Nitrile Isomerization-Alkylations
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Anisylsulfanylmethylisocyanide, Asmic, is a versatile building block whose alkylations provide a range of substituted isocyanides. The anisylsulfanyl group plays a critical role in the sequenced deprotonation-alkylation and the subsequent sulfanyl-lithium exchange. Complexation of the anisylsulfanyl group to BuLi in the presence of TMEDA affords a lithiated isocyanide whose alkylations generate trisubstituted isocyanides. In the absence of TMEDA, BuLi triggers cyanide expulsion to afford a transient carbene; reorientation of cyanide with attack at the carbene affords a lithiated nitrile whose alkylations afford quaternary nitriles. The complexation-induced isocyanide-nitrile rearrangement is exceptionally facile, occurring within 5 min at –78 °C. Detailed mechanistic and computational analyses identify the importance of chelation in the bifurcating mechanism: internal chelation favors cyanide extrusion to form a carbene whereas chelating agents favor arylsulfanyl-lithium exchange to generate a lithiated isocyanide. The combined experimental and computational analyses reveal a new mechanism for isocyanide-nitrile isomerization which provides valuable insight for rapidly assembling substituted isocyanides.
- Alwedi, Embarek,Lujan-Montelongo, J. Armando,Cortés-Mejía, Rodrigo,del Campo, Jorge M.,Altundas, Bilal,Fleming, Fraser F.
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supporting information
p. 4644 - 4648
(2019/07/31)
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- Vinylidenation of Organoboronic Esters Enabled by a Pd-Catalyzed Metallate Shift
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Organoboron “ate” complexes undergo a net vinyl insertion reaction to give 1,1-disubstituted alkenyl boronic esters when treated with stoichiometric allyl acetate and a palladium catalyst. Reactions that employ vinyllithium afforded good to excellent yields after one hour, while reactions that employ vinylmagnesium chloride furnished modest to good yields after 18 hours.
- Aparece, Mark D.,Gao, Chenpeng,Lovinger, Gabriel J.,Morken, James P.
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p. 592 - 595
(2019/01/04)
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- Influences of Phenyl Rings on NHC Ligands with Bicyclic Architectures
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In addition to phosphanes, olefins, amines, and amides, over the past two decades N-heterocyclic carbene (NHC) has emerged as a useful alternative ligand. Based on a number of derivatization studies on NHC ligands, imidazol-2-ylidene and imidazolin-2-ylidene became the standard heterocyclic form, and bulky substituents have commonly been introduced on the nitrogen(s) adjacent to carbenic carbons. Our group previously developed NHCs equipped with noncarbenic carbons with a bicyclic architecture that gives them unique steric properties that make them bulky but accessible. In this study, we synthesized a novel type of NHC ligand that possesses a bicyclo[2.2.1]heptane architecture, and we compared five derivatives using copper-catalyzed allylic arylations with aryl Grignard reagents. The regioselectivity of the substitution obviously indicates that a phenyl ring over an active site has a characteristic effect on the resultant copper catalysts when γ-substitution is the major pathway.
- Ando, Shin,Miyata, Ryota,Matsunaga, Hirofumi,Ishizuka, Tadao
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p. 128 - 139
(2019/01/04)
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- Iron-Catalyzed Cross-Coupling of Alkynyl and Styrenyl Chlorides with Alkyl Grignard Reagents in Batch and Flow
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Transition-metal-catalyzed cross-coupling chemistry can be regarded as one of the most powerful protocols to construct carbon–carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron-based cross-coupling reaction that enables the formation of Csp?Csp3 and Csp2?Csp3 bonds. In a telescoped flow process, the reaction can be combined with the Grignard reagent synthesis. Moreover, flow allows the use of a supporting ligand to be avoided without eroding the reaction selectivity.
- Deng, Yuchao,Wei, Xiao-Jing,Wang, Xiao,Sun, Yuhan,No?l, Timothy
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p. 14532 - 14535
(2019/11/21)
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- Transition-Metal-Free Deaminative Vinylation of Alkylamines
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The amino group is one of the most fundamental structural motifs in natural products and synthetic chemicals. However, amines potential as effective alkylating agents in organic synthesis is still problematic. A unified strategy has been established for deaminative vinylation of the alkylamines with vinyl boronic acids by C?N bond activation under catalyst-free conditions. The key to the high reactivity is the utilization of pyridinium salt-activated alkylamines, with a base as a promoter. The transformation exhibits good functional group compatibility, and includes inexpensive primary amine feedstocks and amino acids. The proposed method can serve as a powerful synthetic method for late-stage modification of complex compounds. Mechanistic experiments suggest that free radical processes are involved in this system. (Figure presented.).
- Hu, Jiefeng,Cheng, Bo,Yang, Xianyu,Loh, Teck-Peng
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supporting information
p. 4902 - 4908
(2019/09/13)
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- Cross-coupling reaction of allylic ethers with aryl Grignard reagents catalyzed by a nickel pincer complex
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A cross-coupling reaction of allylic aryl ethers with arylmagnesium reagents was investigated using β-aminoketonato- and β-diketiminato-based pincer-type nickel(II) complexes as catalysts. An β-aminoketonato nickel(II) complex bearing a diphenylphosphino group as a third donor effectively catalyzed the reaction to afford the target cross-coupled products, allylbenzene derivatives, in high yield. The regioselective reaction of a variety of substituted cinnamyl ethers proceeded to give the corresponding linear products. In contrast, α- and γ-alkyl substituted allylic ethers afforded a mixture of the linear and branched products. These results indicated that the coupling reaction proceeded via a π-allyl nickel intermediate.
- Hashimoto, Toru,Funatsu, Kei,Ohtani, Atsufumi,Asano, Erika,Yamaguchi, Yoshitaka
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- Iron-catalysed allylation-hydrogenation sequences as masked alkyl-alkyl cross-couplings
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An iron-catalysed allylation of organomagnesium reagents (alkyl, aryl) with simple allyl acetates proceeds under mild conditions (Fe(OAc)2 or Fe(acac)2, Et2O, r.t.) to furnish various alkene and styrene derivatives. Mechanistic studies indicate the operation of a homotopic catalyst. The sequential combination of such iron-catalysed allylation with an iron-catalysed hydrogenation results in overall C(sp3)-C(sp3)-bond formation that constitutes an attractive alternative to challenging direct cross-coupling protocols with alkyl halides.
- Bernauer, Josef,Wu, Guojiao,Von Wangelin, Axel
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p. 31217 - 31223
(2019/10/19)
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- Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
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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
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p. 4622 - 4627
(2018/05/22)
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- Manganese-Catalyzed Dual-Deoxygenative Coupling of Primary Alcohols with 2-Arylethanols
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Reported herein is a general and efficient dual-deoxygenative coupling of primary alcohols with 2-arylethanols catalyzed by a well-defined Mn/PNP pincer complex. This reaction is the first example of the catalytic dual-deoxygenation of alcohols using a non-noble-metal catalyst. Both deoxygenative homocoupling of 2-arylethanols (17 examples) and their deoxygenative cross-coupling with other primary alcohols (20 examples) proceeded smoothly to form the corresponding alkenes by a dehydrogenation and deformylation reaction sequence.
- Wang, Yujie,Shao, Zhihui,Zhang, Kun,Liu, Qiang
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supporting information
p. 15143 - 15147
(2018/11/01)
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- Nickel-Catalyzed Direct Coupling of Allylic Alcohols with Organoboron Reagents
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The direct coupling of allylic alcohols with arylboronic acids or their derivatives catalyzed by Ni(cod)2 in the presence of a catalytic amount of base has been developed. A wide variety of allylic substrates or arylboronic acids turned out to be applicable to this catalytic system. The present method does not require the use of ligands for stabilizing the nickel catalyst in most cases or additional activators for activation of allylic alcohols.
- Wang, Gaonan,Gan, Yi,Liu, Yuanhong
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supporting information
p. 916 - 920
(2018/09/22)
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- Aqueous protocol for allylic arylation of cinnamyl acetates with sodium tetraphenylborate using a Bedford-type palladacycle catalyst
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Allylic arylation of cinnamyl acetates with sodium tetraphenylborate using 0.002 mol% of a Bedford-type palladacycle catalyst is described. The developed methodology is applicable for a wide range of cinnamyl acetates furnishing excellent yields of up to 93%. Notably all reactions proceed smoothly under mild reaction conditions in water under an air atmosphere.
- Ghorpade, Seema Arun,Sawant, Dinesh Nanaji,Renn, Dominik,Zernickel, Anna,Du, Weiyuan,Sekar, Nagaiyan,Eppinger, J?rg
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supporting information
p. 6210 - 6214
(2018/04/23)
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- Iron-Catalyzed Grignard Cross-Couplings with Allylic Methyl Ethers or Allylic Trimethylsilyl Ethers
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We have found that cross-coupling between aryl Grignard reagents and allylic methyl ethers proceeded well in the presence of a catalytic amounts of Fe(acac) 3 to afford the corresponding allylic substitution products in good yields. Under the same conditions, allylic trimethylsilyl ethers also reacted with Grignard reagents to give the corresponding cross-coupling products.
- Seto, Chika,Otsuka, Takeshi,Takeuchi, Yoshiki,Tabuchi, Daichi,Nagano, Takashi
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p. 1211 - 1214
(2018/03/26)
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- Direct Reduction of Allylic Alcohols Using Isopropanol as Reductant
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The lithium cation-catalyzed direct reduction of allylic alcohols to alkenes using isopropanol as a hydride donor was developed. The hydride transfer of the in situ-generated lithium isopropoxide to an allylic cation is the key process in this transformation. The reaction generates only water and acetone as byproducts, which highlights the synthetic utility of this method. (Figure presented.).
- Sai, Masahiro
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p. 3482 - 3487
(2018/09/14)
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- Ru-Catalyzed Cross-Dehydrogenative Coupling between Primary Alcohols to Guerbet Alcohol Derivatives: With Relevance for Fragrance Synthesis
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A simple method has been developed for the cross dehydrogenative coupling between two different primary alcohols using readily available RuCl2(PPh3)3 as a precatalyst through the borrowing-hydrogen approach. The present methodology is applicable to a large variety of alcohol derivatives including long chain aliphatic alcohols and heteroaryl alcohols. In addition, the methodology was applied in a straightforward protocol to synthesize commercially available fragrances such as Rosaphen and Cyclamenaldehyde in good yields.
- Manojveer, Seetharaman,Salahi, Saleh,Wendt, Ola F.,Johnson, Magnus T.
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p. 10864 - 10870
(2018/09/06)
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- Single-Step Synthesis of Dinuclear Neutral Gold(I) Complexes with Bridging Di(N-heterocyclic carbene) Ligands and Their Catalytic Performance in Cross Coupling Reactions and Alkyne Hydroamination
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We report on a single-step procedure for the synthesis of dinuclear gold(I) complexes with bridging di(N-heterocyclic carbene) (diNHC) ligands of general formula Au2Br2L1-9 (L = diNHC). The obtained complexes differ in the bridging group between the carbene donors and in the terminal wingtip substituents at the imidazol-2-ylidene rings. The complexes have been characterized by means of elemental analysis, NMR spectroscopy, ESI-MS spectrometry, and single-crystal X-ray structure analysis. The dinuclear gold(I) complexes have been tested as homogeneous catalysts in technologically relevant reactions such as the cross coupling between phenylboronic acid and aryl bromides and the intermolecular hydroamination of alkynes. The catalytic performance has been compared for complexes Au2Br2L1-9 and the benchmark mononuclear complex IPrAuCl.
- Baron, Marco,Battistel, Edoardo,Tubaro, Cristina,Biffis, Andrea,Armelao, Lidia,Rancan, Marzio,Graiff, Claudia
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p. 4213 - 4223
(2018/11/23)
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