- Enantioselective synthesis of 3-substituted dihydrobenzofurans through iridium-catalyzed intramolecular hydroarylation
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Intramolecular hydroarylationviaC-H activation is one of the most powerful methods to synthesize carbo- and heterocyclic compounds, whereas we still have room for developing a highly enantioselective variant of the reaction. Here we describe Ir-catalyzed enantioselective intramolecular hydroarylation ofm-allyloxyphenyl ketones. The enantioselective cyclization was efficiently catalyzed by a cationic iridium complex coordinated with a conventional chiral bisphosphine ligand to give benzofurans in high yields with high enantioselectivity. A carbonyl group of ketones functioned as an effective directing group for the C-H activation. In terms of synthetic utility, we also achieved one-pot synthesis of chiral 3-substituted dihydrobenzofurans from readily available allylic carbonates andm-hydroxyacetophenonesviasequential Pd-catalyzed allylic substitution and Ir-catalyzed intramolecular hydroarylation.
- Nishimura, Takahiro,Sakamoto, Kana
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supporting information
p. 684 - 690
(2021/02/06)
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- Palladium-Catalyzed Oxidative Allylic Alkylation of N -Hydroxy-imides
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A palladium-catalyzed oxidative C-H allylic alkylation of N -hydroxyimides has been developed. This transformation provided valuable N -allyloxypyrrolidinediones in moderate to excellent yields using operationally simple, ligand free, and mild reaction co
- Ahire, Milind M.,Ayyagari, Narasimham,Belani, Jitendra D.,Ngo, Kevin,Sunnam, Sunil Kumar,Yang, Minxi
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- Size-Exclusion Borane-Catalyzed Domino 1,3-Allylic/Reductive Ireland–Claisen Rearrangements: Impact of the Electronic and Structural Parameters on the 1,3-Allylic Shift Aptitude
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The reductive Ireland–Claisen rearrangement through borane-mediated hydrosilylation is reported. The method employs a borane catalyst with a special structural design and affords access to synthetically relevant products with high diastereoselectivity. Depending on electronic and structural parameters, the reaction can be coupled with a 1,3-allylic shift, thus the valence isomer of the Ireland–Claisen product is formed.
- Fegyverneki, Dániel,Kolozsvári, Natália,Molnár, Dániel,Egyed, Orsolya,Holczbauer, Tamás,Soós, Tibor
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supporting information
p. 2179 - 2183
(2019/01/04)
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- Palladium-catalyzed allylic C-H oxidation under simple operation and mild conditions
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We discovered an effective and simple system (Pd/BQ/air/r.t.) for making allylic alcohols through Pd-catalyzed allylic C-H bond functionalization. This approach exhibits advantages due to its simple operation, mild conditions, and environmentally benign features. By modifying reaction conditions, it can be suitable for preparing unsaturated aldehydes, allylic esters, ethers, and amines.
- Guo, Yunlong,Shen, Zengming
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supporting information
p. 3103 - 3107
(2019/03/26)
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- Sequential Palladium-Catalyzed Allylic Alkylation/retro-Dieckmann Fragmentation Strategy for the Synthesis of α-Substituted Acrylonitriles
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A straightforward synthesis of α-substituted acrylonitriles is described using 4-cyano-3-oxotetrahydro-thiophene (c-THT) as an acrylonitrile surrogate. This unprecedented two-step sequence featuring a palladium-catalyzed allylic alkylation (Pd-AA) and a retro-Dieckmann fragmentation provides a general entry into diversely substituted 1,4-dienes.
- Katsina, Tania,Sharma, Sachi Prem,Buccafusca, Roberto,Quinn, Derek J.,Moody, Thomas S.,Arseniyadis, Stellios
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p. 9348 - 9352
(2019/11/20)
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- Highly Enantioselective, Base-Free Synthesis of α-Quaternary Succinimides through Catalytic Asymmetric Allylic Alkylation
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The synthesis of diversely substituted five-membered ring succinimide derivatives is reported featuring a direct, base-free, palladium-catalyzed asymmetric allylic alkylation. The method allows a straightforward access to the desired heterocyclic scaffold bearing an all-carbon α-quaternary stereogenic center in high yields and good to excellent enantioselectivities. To further demonstrate the synthetic utility of the method, the allylated products were further converted to various versatile chiral building blocks, including a chiral pyrrolidine and a spirocyclic derivative, using selective transformations.
- Song, Tao,Arseniyadis, Stellios,Cossy, Janine
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p. 8076 - 8080
(2018/06/15)
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- Hydroamination versus Allylic Amination in Iridium-Catalyzed Reactions of Allylic Acetates with Amines: 1,3-Aminoalcohols via Ester-Directed Regioselectivity
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In the presence of a neutral dppf-modified iridium catalyst and Cs2CO3, linear allylic acetates react with primary amines to form products of hydroamination with complete 1,3-regioselectivity. The collective data, including deuterium labeling studies, corroborate a catalytic mechanism involving rapid, reversible acetate-directed aminoiridation with inner-sphere/outer-sphere crossover followed by turnover-limiting proto-demetalation mediated by amine.
- Kim, Seung Wook,Wurm, Thomas,Brito, Gilmar A.,Jung, Woo-Ok,Zbieg, Jason R.,Stivala, Craig E.,Krische, Michael J.
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p. 9087 - 9090
(2018/08/03)
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- Heterotelechelic Polymers by Ring-Opening Metathesis and Regioselective Chain Transfer
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Heterotelechelic polymers were synthesized by a kinetic telechelic ring-opening metathesis polymerization method relying on the regioselective cross-metathesis of the propagating Grubbs’ first-generation catalyst with cinnamyl alcohol derivatives. This procedure allowed the synthesis of hetero-bis-end-functional polymers in a one-pot setup. The molecular weight of the polymers could be controlled by varying the ratio between cinnamyl alcohol derivatives and monomer. The end functional groups can be changed using different aromatically substituted cinnamyl alcohol derivatives. Different monomers were investigated and the presence of the functional groups was shown by NMR spectroscopy and MALDI-ToF mass spectrometry. Labeling experiments with dyes were conducted to demonstrate the orthogonal addressability of both chain ends of the heterotelechelic polymers obtained.
- Liu, Peng,Yasir, Mohammad,Ruggi, Albert,Kilbinger, Andreas F. M.
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p. 914 - 917
(2018/01/01)
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- S,O-ligand-promoted palladium-catalyzed C–H olefination of arenes with allylic substrates
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An efficient catalytic system for the C–H olefination of arenes with different allylic substrates is reported. The catalytic system is based on Pd(OAc)2 and a readily accessible bidentate S,O-ligand. The methodology shows high activity with a wide range of arenes, including bulky and, electron-rich and -poor arenes. The applicability of this catalyst is demonstrated in the late-stage functionalization of the complex molecule O-methylestrone.
- Naksomboon, Kananat,álvarez-Casao, Yolanda,Uiterweerd, Michiel,Westerveld, Nick,Maciá, Beatriz,Fernández-Ibá?ez, M. ángeles
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supporting information
p. 379 - 382
(2017/12/28)
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- Hydrazone-Pd-catalyzed direct intermolecular reaction of: O -alkynylphenols with allylic acetates
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We found that the hydrazone-Pd-catalyzed direct intermolecular reaction of o-alkynylphenols with allylic acetates afforded the corresponding 2-substituted-3-allylbenzofuran derivatives. This reaction proceeded smoothly at room temperature using a hydrazon
- Watanabe, Kohei,Mino, Takashi,Ishikawa, Eri,Masuda, Chihiro,Yoshida, Yasushi,Sakamoto, Masami
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supporting information
p. 575 - 584
(2018/02/07)
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- Oxygenation of Simple Olefins through Selective Allylic C?C Bond Cleavage: A Direct Approach to Cinnamyl Aldehydes
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A novel metal-free allylic C?C σ-bond cleavage of simple olefins to give valuable cinnamyl aldehydes is reported. 1,2-Aryl or alkyl migration through allylic C?C bond cleavage occurs in this transformation, which is assisted by an alkyl azide reagent. This method enables O-atom incorporation into simple unfunctionalized olefins to construct cinnamyl aldehydes. The reaction features simple hydrocarbon substrates, metal-free conditions, and high regio- and stereoselectivity.
- Liu, Jianzhong,Wen, Xiaojin,Qin, Chong,Li, Xinyao,Luo, Xiao,Sun, Ao,Zhu, Bencong,Song, Song,Jiao, Ning
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supporting information
p. 11940 - 11944
(2017/09/20)
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- Stereoselective and Site-Specific Allylic Alkylation of Amino Acids and Small Peptides via a Pd/Cu Dual Catalysis
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We report a stereoselective and site-specific allylic alkylation of Schiff base activated amino acids and small peptides via a Pd/Cu dual catalysis. A range of noncoded α,α-dialkyl α-amino acids were easily synthesized in high yields and with excellent enantioselectivities (up to >99% ee). Furthermore, a direct and highly stereoselective synthesis of small peptides with enantiopure α-alkyl or α,α-dialkyl α-amino acids residues incorporated at specific sites was accomplished using this dual catalyst system.
- Huo, Xiaohong,He, Rui,Fu, Jingke,Zhang, Jiacheng,Yang, Guoqiang,Zhang, Wanbin
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p. 9819 - 9822
(2017/08/02)
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- p-Cymene as Solvent for Olefin Metathesis: Matching Efficiency and Sustainability
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The underexploited biorenewable p-cymene is employed as a solvent for the metathesis of various substrates. p-Cymene is a nontoxic compound that can be obtained in large amounts as a side product of the cellulose and citrus industry. For the cross-metathesis of estragole with methyl acrylate, this solvent prevents the consecutive double-bond isomerization of the product and affords the best yield of all solvents tested. Undesired consecutive isomerization is a major challenge for many substrates in olefin metathesis, including pharmaceutical precursors, and the use of p-cymene as a solvent may be a way to prevent it. This solvent results in a better metathesis performance than toluene for the three substrates tested in this work, matching its performance for two other substrates.
- Granato, Artur V.,Santos, Alexandra G.,dos Santos, Eduardo N.
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p. 1832 - 1837
(2017/04/27)
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- Terephthalic acid derived ligand-stabilized palladium nanocomposite catalyst for Heck coupling reaction: without surface-modified heterogeneous catalyst
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A new protocol is reported for the synthesis of a heterogeneous palladium nanocomposite stabilized with a terephthalic acid-derived ligand (N,N-bis(4-hydroxy-3-methoxybenzylidene)terephthalohydrazide). This is a highly insoluble ligand in common organic solvents, except dimethylformamide and dimethylsulfoxide. The resulting palladium nanocomposite acts as an efficient catalyst precursor for Mizoroki–Heck coupling reactions conducted under various reaction conditions. The spectral data suggest that the rate, yield and recycling of the catalyst are more effective for C–C coupling reactions. Copyright
- Jithendra kumara,Krishnamurthy,Kumara swamy,Shashi kumar,Naik, Satish,Krishna,Naik, Nagaraj
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- Palladium-catalyzed diastereoselective synthesis of homoaldol equivalent products
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A palladium-catalyzed reaction of easily accessible 3-(pinacolatoboryl)allyl acetates and aldehydes provides facile access to synthetically useful homoaldol equivalent products with high diastereoselectivity. The reaction presumably proceeds via allylation of aldehydes with α-acetoxy allylboronates that produced in situ by reductive elimination from allylic gem-palladium/boryl intermediates.
- Horino, Yoshikazu,Sugata, Miki,Sugita, Tetsu,Aimono, Ataru,Abe, Hitoshi
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p. 2131 - 2134
(2017/05/09)
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- Ruthenium-Catalyzed Cross-Metathesis of Allyl Acetate and Styrenes: A Practical Approach to the Synthesis of Tripolinolate A and Its Analogs
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The scope of the Ru-catalyzed cross-metathesis of allyl acetates and styrenes was explored. A variety of electronically and structurally divergent styrenes were tolerated, and the resultant products were obtained in reasonable yields. The reported method was utilized in the synthesis of inhibitors of the proliferation of glioma and colorectal cancer cells, tripolinolate A and its diacetate analog.
- Araki, Yasuhiro,Topolov?an, Nikola,Kotora, Martin
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supporting information
p. 1736 - 1739
(2017/04/13)
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- Allylic C–H acetoxylation of terminal alkenes over TiO2 supported palladium nanoparticles using molecular oxygen as the oxidant
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A method for synthesizing linear allylic acetates from terminal alkenes over TiO2 supported Pd nanoparticles (NPs) has been developed, in which O2 serves as the sole oxidant. Good catalytic activity was performed when using allylbenzene as a substrate and the catalyst can be reused at least five times without activity losing. The catalytic system has a broad substrate scope including transformation of 1,3-butadiene into 1,4-diacetoxy-2-butene, which is an important industrial intermediate for production of 1,4-butanediol. In contrast to previous reports that the Pd-catalyzed allylic acetoxylation is generally promoted by PdII species, the XAFS measurements suggest that this reaction is catalyzed over Pd0 NPs. Additionally, XPS analysis of the catalyst confirms the interaction between Pd and TiO2, which probably promote the initial catalytic procedure.
- Zhang, Zhenzhong,Wu, Qixun,Hashiguchi, Taishin,Ishida, Tamao,Murayama, Haruno,Tokunaga, Makoto
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- Regio- and stereoselective allylic C-H arylation with electron-deficient arenes by 1,1′-Bi-2-naphthol-palladium cooperation
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A palladium-catalyzed allylic C-H arylation reaction with electron-deficient arenes with high regio- and stereoselectivity is reported. This work represents the first successful use of 1,1′-bi-2-naphthol as the ancillary ligand in allylic C-H activation, which is the key factor for chemoselectivity. Furthermore, high selectivity allylic C-H acetoxylation and amination were also successfully achieved under the same catalytic system.
- Wang, Gang-Wei,Zhou, An-Xi,Li, Shi-Xia,Yang, Shang-Dong
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supporting information
p. 3118 - 3121
(2014/06/23)
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- Access to cinnamyl derivatives from arenes and allyl esters by a biomimetic aerobic oxidative dehydrogenative coupling
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An efficient biomimetic aerobic oxidative dehydrogenative alkenylation of arenes with allyl esters is presented. The reaction proceeds under an ambient pressure of oxygen with relatively low catalyst loading of palladium acetate, employing catalytic amounts of electron-transfer mediators (ETMs). This study represents a new environmentally friendly method for the synthesis of cinnamyl derivatives.
- Gigant, Nicolas,Baeckvall, Jan-E.
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supporting information
p. 1664 - 1667
(2014/04/17)
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- Organic synthesis via magnetic attraction: Benign and sustainable protocols using magnetic nanoferrites
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Magnetic nano-catalysts have been prepared using simple modification of iron ferrites. The nm size range of these particles facilitates the catalysis process, as an increased surface area is available for the reaction; the easy separation of the catalysts by an external magnet and their recovery and reuse are additional beneficial attributes. Glutathione bearing nano-ferrites have been used as organocatalysts for the Paal-Knorr reaction and homocoupling of boronic acids. Nanoferrites, post-synthetically modified by ligands, were used to immobilize nanometals (Cu, Pd, Ru, etc.) which enabled the development of efficient, sustainable and green procedures for azide-alkynes-cycloaddition (AAC) reactions, C-S coupling, O-allylation of phenol, Heck-type reactions and hydration of nitriles.
- Nasir Baig,Varma, Rajender S.
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p. 398 - 417
(2013/03/14)
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- Sterically controlled alkylation of arenes through iridium-catalyzed C-H borylation
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Complementary chemistry: A one-pot method for the site-selective alkylation of arenes controlled by steric effects is reported. The process occurs through Ir-catalyzed C-H borylation, followed by Pd- or Ni-catalyzed coupling with alkyl electrophiles. This selectivity complements that of the typical Friedel-Crafts alkylation; meta-selective alkylation of a broad range of arenes with various electronic properties and functional groups occurs in good yield with high site selectivity. Copyright
- Robbins, Daniel W.,Hartwig, John F.
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supporting information
p. 933 - 937
(2013/02/25)
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- Heck-Matsuda reaction of arenediazonium salts in water
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The palladium-catalyzed arylation of alkenes with aryldiazonium salts can be carried out through an environmentally friendly protocol using neat water low palladium loadings at room temperature under base-additive- and ligand-free conditions.
- Salabert, Jordi,Sebastián, Rosa María,Vallribera, Adelina,Cívicos, José Francisco,Nájera, Carmen
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p. 2655 - 2659
(2013/03/28)
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- A simple and facile Heck-type arylation of alkenes with diaryliodonium salts using magnetically recoverable Pd-catalyst
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The Heck-type arylation of alkenes was achieved in aqueous polyethylene glycol using a magnetically recoverable heterogenized palladium catalyst employing diaryliodonium salts under ambient conditions. The benign reaction medium and the stability of the catalyst are the salient features of this simple and facile protocol.
- Vaddula, Buchi Reddy,Saha, Amit,Leazer, John,Varma, Rajender S.
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supporting information; experimental part
p. 2133 - 2136
(2012/09/08)
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- Pd(II)-catalyzed direct olefination of arenes with allylic esters and ethers
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A convenient Pd(II)-catalyzed direct olefination of unactivated arenes with allylic esters and ethers via C-H activation was demonstrated. Under the typical conditions, various aryl-substituted allylic esters and ethers can be prepared. Georg Thieme Verlag Stuttgart - New York.
- Shang, Xiaojie,Xiong, Yun,Zhang, Yuexia,Zhang, Lei,Liu, Zhongquan
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supporting information; experimental part
p. 259 - 262
(2012/03/08)
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- Aryliodine(III) diacetates as substrates for Pd-Ag catalyzed arylation of alkenes
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An unprecedented application of aryliodine(III) diacetates as substrates in Pd-Ag catalyzed arylation of alkenes is described. The mechanistic studies revealed that the binary Pd-Ag catalysis leads to the decomposition of aryliodine(III) diacetates to oxygen and aryl iodides followed by arylation of alkenes forming Heck-type products. Under optimized conditions both electron-rich and electron-deficient alkenes undergo arylation in high yields. Advantageously, the reaction proceeds smoothly in water as a solvent and neither organic ligands nor inert atmosphere are required.
- Evdokimov, Nikolai M.,Kornienko, Alexander,Magedov, Igor V.
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experimental part
p. 4327 - 4329
(2011/09/12)
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- Palladium-catalyzed 1,1-aryloxygenation of terminal olefins
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This paper describes the 1,1-arylacetoxylation of diverse α-olefins using organostannanes and hypervalent iodine oxidants. The reaction provides a convergent approach for generating a C-C and a C-O bond as well as a new stereocenter in a single catalytic transformation.(Figure Presented)
- Satterfield, Andrew D.,Kubota, Asako,Sanford, Melanie S.
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supporting information; experimental part
p. 1076 - 1079
(2011/04/26)
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- Sulfur-directed olefin oxidations: Observation of divergent reaction mechanisms in the palladium-mediated acetoxylation of unsaturated thioacetals
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The Pd-mediated oxidation of unsaturated thioacetals gives either allyl or vinyl esters, depending on the substrate structure. We report the characterization of a range of sulfur-stabilized palladium intermediates via a combined computational and experime
- Mann, Sam E.,Aliev, Abil E.,Tizzard, Graham J.,Sheppard, Tom D.
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scheme or table
p. 1772 - 1775
(2011/06/22)
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- Silica gel-mediated rearrangement of allylic acetates. Application to the synthesis of 1,3-enynes
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Silica gel was found to efficiently promote the rearrangement of allylic acetates into their most stable regioisomers under microwave irradiation. The reaction is easy to perform and eco-friendly. This method was applied to the metal-free synthesis of 1,3-enynes.
- Serra-Muns, Anna,Guerinot, Amandine,Reymond, Sebastien,Cossy, Janine
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supporting information; experimental part
p. 4178 - 4180
(2010/08/07)
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- PdII-catalyzed highly selective arylation of allyl esters via C-H functionalization of unreactive arenes with retention of the traditional leaving group
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A highly selective Fujiwara-Moritani oxidative Heck reaction of allyl esters with unreactive arenes via C - H bond activation was developed, in which -H elimination is highly chemo-, regio- and stereoselective. Moreover, even electron-deficient arenes are tolerated in this type of C - H activation. 2010 Wiley-VCH Verlag GmbH Co. KGaA, Weinheim.
- Pan, Delin,Yu, Miao,Chen, Wei,Jiao, Ning
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experimental part
p. 1090 - 1093
(2011/07/08)
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- Allylic C-H acetoxylation with a 4,5-diazafluorenone-ligated palladium catalyst: A ligand-based strategy to achieve aerobic catalytic turnover
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Pd-catalyzed C-H oxidation reactions often require the use of oxidants other than O2. Here we demonstrate a ligand-based strategy to replace benzoquinone with O2 as the stoichiometric oxidant in Pd-catalyzed allylic C-H acetoxylation. Use of 4,5-diazafluorenone (1) as an ancillary ligand for Pd(OAc)2 enables terminal alkenes to be converted to linear allylic acetoxylation products in good yields and selectivity under 1 atm O 2. Mechanistic studies have revealed that 1 facilitates C-O reductive elimination from a π-allyl-PdII intermediate, thereby eliminating the requirement for benzoquinone in this key catalytic step.
- Campbell, Alison N.,White, Paul B.,Guzei, Ilia A.,Stahl, Shannon S.
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supporting information; experimental part
p. 15116 - 15119
(2011/01/06)
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- Simple and efficient method for acetylation of alcohols, phenols, amines, and thiols using anhydrous NiCl2 under solvent-free conditions
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Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac2O) in the presence of 0.1mol% (13mg) anhydrous NiCl2, an inexpensive and easily available catalyst, is described. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.
- Meshram, Gangadhar,Patil, Vishvanath D.
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experimental part
p. 4384 - 4395
(2010/04/29)
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- Mechanistic investigations of bipyrimidine-promoted palladium-catalyzed allylic acetoxylation of olefins
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Several pyridine-like ligands were found to improve Pd(OAc) 2-catalyzed allylic oxidation of allylbenzene to cinnamyl acetate by p-benzoquinone in acetic acid. The best ligand examined, bipyrimidine, was used to identify the catalyst precursor for this system, (bipyrimidine)Pd(OAc) 2, which was fully characterized. Mechanistic studies suggest the reaction takes place through disproportionation of (bipyrimidine)Pd(OAc) 2 to form a bipyrimidine-bridged dimer, which reacts with olefin to form a PdII-olefin adduct, followed by allylic C-H activation to produce (η3-allyl)PdII species. The (η3-allyl)PdII intermediate undergoes a reversible acetate attack to generate a Pd0-(allyl acetate) adduct, which subsequently reacts with p-benzoquinone to release allyl acetate and regenerate (bipyrimidine)Pd(OAc)2. No KIE is observed for the competition experiment between allylbenzene-d0 and allylbenzene-d5 (CD2=CDCD2C6H5), suggesting that allylic C-H activation is not rate-determining. Catalytic allylic acetoxylations of other terminal olefins as well as cyclohexene were also effected by (bipyrimidine)Pd(OAc)2.
- Lin, Bo-Lin,Labinger, Jay A.,Bercaw, John E.
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experimental part
p. 264 - 271
(2009/10/23)
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- Highly regio- and stereoselective Heck reaction of allylic esters with arenediazonium salts: Application to the synthesis of kavalactones
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Image Presented A highly efficient palladium-catalyzed Heck reaction of allylic esters with arenediazonium salts is described. The reaction proceeds under mild conditions, with excellent to total regio- and stereochemical control and with retention of the traditional leaving group. Furthermore, the generality of the present methodology is illustrated by the short total synthesis of the natural kavalactones, yangonine, (±)-methysticin, and (±)-dihydromethysticin.
- Moro, Angelica Venturini,Cardoso, Flavio Sega Pereira,Correia, Carlos Roque Duarte
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supporting information; experimental part
p. 3642 - 3645
(2011/02/25)
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- Control of chemo-, regio-, and stereoselectivities in ligand-free Pd-catalyzed oxidative heck reactions of arylboronic acids or alkenylboronate with allyl esters
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A ligand-free Pd-catalyzed highly selective oxidative Heck reaction of organoboronic acids with allyl esters was developed. β-H elimination is highly chemoselectively controlled, leading to γ-substituted allyl esters, which is contrary to the traditional
- Su, Yijin,Jiao, Ning
-
supporting information; experimental part
p. 2980 - 2983
(2009/12/05)
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- Ligand-free Pd-catalyzed highly selective arylation of allylic esters with retention of the traditional leaving group
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(Chemical Equation Presented) What leaving group? Organic halides and allylic esters undergo efficient Pd-catalyzed Heck reactions under mild conditions in air to form a new C-C bond without elimination of the β-OAc group in the intermediate palladium complex. Instead a highly regioselective β-H elimination takes place to provide substituted derivatives of allylic alcohols (see scheme).
- Pan, Delin,Chen, Anjun,Su, Yijin,Zhou, Wang,Li, Si,Jia, Wei,Xiao, Juan,Liu, Qingjian,Zhang, Liangren,Jiao, Ning
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supporting information; experimental part
p. 4729 - 4732
(2009/02/06)
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- Direct, iridium-catalyzed enantioselective and regioselective allylic etherification with aliphatic alcohols
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(Chemical Equation Presented) From alcohol to ether: Iridium-catalyzed allylations yield α chiral ether derivatives directly from aliphatic alcohols with a simple alkali metal base (see equation). These reactions form ethers from primary, secondary, and tertiary alkoxides with high enantioselectivity. By-products from isomerization were suppressed by the use of an alkyne additive.
- Ueno, Satoshi,Hartwig, John F.
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p. 1928 - 1931
(2008/12/22)
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- DDQ catalyzed benzylic acetoxylation of arylalkanes: a case of exquisitely controlled oxidation under sonochemical activation
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Acetoxylated arylalkanes are selectively obtained via sonochemical activation of DDQ catalyzed benzylic oxidation of arylalkanes in the presence of anhydrous acetic acid. The method gives an exquisite control of benzylic acetoxylation under ultrasound, in contrast to the uncontrolled oxidation observed under conventional heating or microwave activation. In addition, the developed method could be?a useful strategy for the synthesis of industrially important enantiopure benzyl alcohols due to the easy amenability of obtained acetoxylated products toward chiral resolution.
- Kumar, Vinod,Sharma, Abhishek,Sharma, Meenakshi,Sharma, Upendra K.,Sinha, Arun K.
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p. 9718 - 9723
(2008/02/12)
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- Ruthenium-catalysed linear-selective allylic alkylation of allyl acetates
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The regioselectivity in the ruthenium-catalysed allylic alkylation of mono substituted allyl acetates with the malonate anion was highly controlled by Ru3(CO)12 with 2-(diphenylphosphino)benzoic acid, and the linear-type alkylated product was obtained. The Royal Society of Chemistry.
- Kawatsura, Motoi,Ata, Fumio,Wada, Shohei,Hayase, Shuichi,Uno, Hidemitsu,Itoh, Toshiyuki
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p. 298 - 300
(2007/10/03)
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- Retention of regiochemistry of monosubstituted allyl acetates in the ruthenium catalysed allylic alkylation with malonate anion
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In the RuCl2(p-cymene)/PPh3 catalysed regioselective allylic alkylation of monosubstituted allyl acetates with malonate anion, the selective substitution at the position originally substituted with acetate was observed. The Royal Society of Chemistry.
- Kawatsura, Motoi,Ata, Fumio,Hayase, Shuichi,Itoh, Toshiyuki
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p. 4283 - 4285
(2008/03/28)
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- Sequential catalytic isomerization and allylic substitution. Conversion of racemic branched allylic carbonates to enantioenriched allylic substitution products
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A catalytic protocol for the conversion of readily accessible racemic, branched aromatic allylic esters to branched allylic amines, ethers, and alkyls has been developed. Palladium-catalyzed isomerization of branched allylic esters to terminal allylic esters, followed by sequential iridium-catalyzed allylic substitution, gave the branched allylic products in good yield with high regioisomeric and enantiomeric selectivity. Both electron-rich and electron-poor branched allylic esters gave products in >90% ee. High enantiomeric excesses were also observed for the products from the reactions of 2-thienyl acetates and dienyl carbonates. Copyright
- Shekhar, Shashank,Trantow, Brian,Leitner, Andreas,Hartwig, John F.
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p. 11770 - 11771
(2007/10/03)
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- The photochemistry of ring-substituted cinnamyl acetates
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The photochemistry of the (E)-cinnamyl acetates ((E)-1-aryl-3-propenyl acetates, 8a-8e) with substituents H, 4-CH3O, 3-CH3O, 4-CF3, and 3-CF3, respectively, was examined in both cyclohexane and methanol solvents. Alkene isomerization (E to Z) occurred more efficiently than other reactions and evidence is presented that this process occurs from the excited triplet state. In a slower process, 1,3-migration of the acetoxy group led to the rearranged 3-aryl-3-propenyl acetate isomers (9a-9e) as the major pathway, particularly in cylohexane. In methanol, the isomeric ethers 3-aryl-3-methoxypropene (14) and 1-aryl-3-methoxypropene (15) were formed by reaction of methanol with the photochemically generated cation. The combined yield of 14 and 15 (95% and 5%, respectively) was quantitative for the 4-methoxyphenyl compound (8b). Independent irradiations of the isomers 9a-9c demonstrated that the ethers 14 and 15 were primary photoproducts from 8 and not secondary photoproducts from 9. Fluorescence quantum yields and excited singlet state lifetimes indicated that the reactions, other than the E to Z isomerization, are from the excited singlet state.
- Fleming,Renault,Grundy,Pincock
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p. 1146 - 1154
(2007/10/03)
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- Ruthenium-catalyzed olefin cross metathesis of styrenes as an alternative to the Heck and cross-coupling reactions
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The use of olefin cross metathesis as a method for the formation of styrenyl-olefins is described using allylic substituted olefins and electron-deficient olefins. These methods provide an orthogonal method to alternative olefination strategies, such as the Heck reaction. These methods have also been employed in the total synthesis of 3-flavanols.
- Chatterjee, Arnab K.,Toste, F. Dean,Choi, Tae-Lim,Grubbs, Robert H.
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p. 634 - 637
(2007/10/03)
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- Synthesis of 2,3-dihydrobenzofurans by Mn(OAc)3-based oxidative cycloaddition of 2-cyclohexenones with alkenes. Synthesis of (±)-conocarpan
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Oxidative cycloaddition of a 2-cyclohexenone or α-tetralone and an alkene with dried Mn(OAc)3 in benzene at 80-140 °C provides a general route to dihydrobenzofurans 15 and dihydronaphthofurans 17. Although the yields are modest, this one-pot reaction provides simple access to these compounds, which have previously been prepared by multistep routes. Oxidative cycloaddition of 2-cyclohexenones with β-methylstyrenes provides a new route to benzofuranoid neolignans, which was applied to the synthesis of conocarpan (22). The formation of 2-acetoxyhexanedioic acids 27 and 47 from acetoxylation of 2-cyclohexenones in HOAc, but not in benzene, opens up a new class of Mn(OAc)3 reactions and explains Watt and Demir's discovery that much higher yields of α'-acetoxy enones are obtained in benzene than in HOAc.
- Snider, Barry B.,Han, Luning,Xie, Chaoyu
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p. 6978 - 6984
(2007/10/03)
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- Electron-transfer Processes: Oxidation of α- and β-Alkenylbenzenes by Peroxydisulphate in Acetic Acid
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Oxidation of α- and β-unsaturated alkylbenzenes by peroxydisulphate in acetic acid gives side-chain acetoxylation with formation of the corresponding glycol diacetates and compounds (10), respectively.The reaction is catalysed by transition-metal salts, among which cupric acetate gives the best results.Generally, electron-releasing substituents on the benzene ring increase the yield and improve the selectivity.The same substrates are oxidized in water under Ag+ catalysis to the corresponding aldehydes.The different behaviour in the two solvents is ascribed to the difference in reactivity between the primary oxidation products and the starting olefin, whereas the initial oxidation step is suggested to occur in both cases via an electron-transfer process from the olefin to the sulphate radical anion.
- Citterio, Attilio,Arnoldi, Claudio,Giordano, Claudio,Castaldi, Grasiano
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p. 891 - 896
(2007/10/02)
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- PALLADIUM-CATALYZED ALLYLIC OXIDATION OF OLEFINS BY t-BUTYL HYDROPEROXIDE AND TELLURIUM(IV) OXIDE
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Treatment of several cyclic olefins, β-pinene, allylbenzene and estragole with palladium(II) salt in acetic acid in the presence of t-butyl hydroperoxide and tellurium(IV) oxide afforded mainly the corresponding allylic acetates.The reaction proceeded catalytically with palladium(II) salt, t-BuOOH working as a reoxidazing agent.
- Uemura, Sakae,Fukuzawa, Shin-ichi,Toshimitsu, Akio,Okano, Masaya
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- RHODIUM(II) ACETATE: AN EFFECTIVE HOMOGENEOUS CATALYST FOR SELECTIVE ALLYLIC OXIDATION AND CARBON-CARBON BOND FISSION OF OLEFINS
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Treatment of some cyclic olefins and allylbenzene with Rh2(OAc)4 in acetic acid in the presence of t-BuOOH gave the corresponding enones and allylic acetates, the former being predominant, Application to several styrene derivatives resulted in a selective C=C bond fission to give benzaldehyde or acetophenone.It is suggested that the reaction proceeds catalytically with Rh(II) acetate via an ionic pathway.
- Uemura, Sakae,Patil, Suresh R.
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p. 1743 - 1746
(2007/10/02)
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