- Facile Synthesis of Chiral Arylamines, Alkylamines and Amides by Enantioselective NiH-Catalyzed Hydroamination
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Regio- and enantioselective hydroarylamination, hydroalkylamination and hydroamidation of styrenes have been developed by NiH catalysis with a simple bioxazoline ligand under mild conditions. A wide range of enantioenriched benzylic arylamines, alkylamines and amides can be easily accessed by nitroarenes, hydroxylamines and dioxazolones, respectively as amination reagents. The chiral induction in these reactions is proposed to proceed through an enantiodifferentiating syn-hydronickellation step.
- Meng, Lingpu,Yang, Jingjie,Duan, Mei,Wang, You,Zhu, Shaolin
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supporting information
p. 23584 - 23589
(2021/09/28)
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- Selecting double bond positions with a single cation-responsive iridium olefin isomerization catalyst
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The catalytic transposition of double bonds holds promise as an ideal route to alkenes of value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, normally requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst selectively produces either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on noncovalent modifications.
- Camp, Andrew M.,Kita, Matthew R.,Blackburn, P. Thomas,Dodge, Henry M.,Chen, Chun-Hsing,Miller, Alexander J.M.
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supporting information
p. 2792 - 2800
(2021/03/01)
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- Cobalt-Catalyzed Z to e Isomerization of Alkenes: An Approach to (E)-β-Substituted Styrenes
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An efficient cobalt-catalyzed Z to E isomerization of β-substituted styrenes using the amido-diphosphine ligand was developed, delivering the (E)-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of (Z)- and (E)-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.
- Liu, Hongmei,Xu, Man,Cai, Cheng,Chen, Jianhui,Gu, Yugui,Xia, Yuanzhi
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p. 1193 - 1198
(2020/02/04)
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- RETRACTED ARTICLE: Copper-Catalyzed Decarboxylative C(sp2)-C(sp3) and C(sp)-C(sp3) Coupling of Substituted Cinnamic Acids and 3-Phenyl Propiolic Acid with N-Tosyl Oxaziridines
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A mild and efficient strategy for decarboxylative C(sp2)-C(sp3) and C(sp)-C(sp3) coupling of α,β-unsaturated carboxylic acids such as substituted cinnamic acids and 3-phenyl propiolic acid with N-Tosyl oxaziridines was developed. The corresponding products were achieved in moderate to good yields with excellent stereoselectivity. Base-free and oxidant-free conditions allow good functional group tolerance. Radical inhibitors such as TEMPO and BHT completely suppressed the reactions suggesting a radical mechanism was involved. This study is supposed to broaden the frontier of oxaziridines' chemistry and to open up a novel cascade for alkylating reagents.
- Nguyen, Bich-Ngoc,Cao, Hai-Thuong
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supporting information
p. 5912 - 5915
(2019/08/07)
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- Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis
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We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.
- Meng, Qing-Yuan,Schirmer, Tobias E.,Katou, Kousuke,K?nig, Burkhard
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p. 5723 - 5728
(2019/04/03)
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- Orthogonally protected 1,2-diols from electron-rich alkenes using metal-free olefin syn-dihydroxylation
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A new method for the stereoselective metal-free syn-dihydroxylation of electron-rich olefins is reported, involving reaction with TEMPO/IBX in trifluoroethanol (TFE) or hexafluoroisopropanol (HFIP) and the addition of a suitable nucleophile. Orthogonally
- Colomer, Ignacio,Barcelos, Rosimeire Coura,Christensen, Kirsten E.,Donohoe, Timothy J.
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p. 5880 - 5883
(2016/11/29)
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- Direct fluorination of styrenes
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We have developed a practical method to synthesize fluorostyrene compounds. A mild and regioselective mono-fluorination reaction occurred smoothly for various di- and trisubstituted styrenes in the presence of RuCl3 and N-fluorobenzenesulfonimide (NFSI). A tandem alkyne hydroarylation-olefin fluorination reaction was also developed using an Au catalyst.
- Shao, Qian,Huang, Yong
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supporting information
p. 6584 - 6586
(2015/04/14)
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- Photocatalytic synthesis of dihydrobenzofurans by oxidative [3+2] cycloaddition of phenols
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We report a protocol for oxidative [3+2] cycloadditions of phenols and alkenes applicable to the modular synthesis of a large family of dihydrobenzofuran natural products. Visible-light-activated transition metal photocatalysis enables the use of ammonium persulfate as an easily handled benign terminal oxidant. The broad range of organic substrates that are readily oxidized by photoredox catalysis suggests that this strategy may be applicable to a variety of useful oxidative transformations.
- Blum, Travis R.,Zhu, Ye,Nordeen, Sarah A.,Yoon, Tehshik P.
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supporting information
p. 11056 - 11059
(2015/03/30)
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- Alkyl transfer from C-C cleavage: Replacing the nitro group of nitro-olefins
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Alkyl substituted Hantzsch esters are rationally used as alkylation reagents to replace the nitro groups of nitro olefins to give excellent yields of trans-olefins. The reaction mechanism is considered to proceed through a free radical mechanism, which is different from the corresponding transfer alkylation of imines. This journal is the Partner Organisations 2014.
- Li, Guangxun,Wu, Lei,Lv, Gang,Liu, Hongxin,Fu, Qingquan,Zhang, Xiaomei,Tang, Zhuo
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p. 6246 - 6248
(2014/06/09)
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- Pd0-mediated rapid coupling of methyl iodide with excess amounts of benzyl- and cinnamylboronic acid esters: Efficient method for incorporation of positron-emitting 11C radionuclide into organic frameworks by coupling between two sp<
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Pd0-mediated rapid cross coupling between sp3- hybridized carbons of CH3I and benzyl- or cinnamylboronic acid esters using [Pd{P(tert-C4H9)3}2]/CsF in DMF/H2O gave the
- Koyama, Hiroko,Zhang, Zhouen,Ijuin, Ryosuke,Siqin,Son, Jeongwan,Hatta, Yuma,Ohta, Masashi,Wakao, Masahiro,Hosoya, Takamitsu,Doi, Hisashi,Suzuki, Masaaki
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p. 9391 - 9401
(2013/07/27)
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- A novel and efficient method for the olefination of carbonyl compounds with Grignard reagents in the presence of diethyl phosphite
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The widely available carbonyl compounds react with Grignard reagents in the presence of diethyl phosphite to give the corresponding olefins in good to excellent yields: A range of conjugated dienes, terminal olefins, multisubstituted-alkenes and conjugated enynes could be readily obtained by the method in mild conditions.
- Wang, Tongqiang,Hu, Yuanyuan,Zhang, Songlin
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supporting information; experimental part
p. 2312 - 2315
(2010/07/09)
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- Highly selective dimerization of styrenes and linear co-dimerization of styrenes with ethylene catalyzed by a ruthenium complex
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(Chemical Equation Presented) Heads you win: An unusual head-to-head dimerization of styrenes has been developed using the zero-valent ruthenium catalyst [Ru(η6-cot)(η2-dmfm)2] (cot = 1,3,5-cyclooctatriene, dmfm = dimethyl fumarate) in the presence of primary alcohols to give the homo-dimer in high regio- and stereoselectivity. The catalyst system is also effective for the selective co-dimerization of styrenes with ethylene to give the co-dimer in high yield.
- Kondo, Teruyuki,Takagi, Daisuke,Tsujita, Hiroshi,Ura, Yasuyuki,Wada, Kenji,Mitsudo, Take-Aki
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p. 5958 - 5961
(2008/09/18)
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- Copper catalyzed enantioselective allylic substitution by MeMgX
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Methyl Grignard undergoes highly regio (>90/10) and enantioselective (ee 91-96%) copper catalyzed allylic substitution on cinnamyl-type chlorides. CuBr (3%) and 3.3% of a chiral phosphoramidite ligand are sufficient for a complete reaction. The synthesis of a precursor of (+)-Naproxen is described. The reaction can be extended to alkyl substituted allylic chlorides (ee 72%).
- Tissot-Croset, Karine,Alexakis, Alexandre
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p. 7375 - 7378
(2007/10/03)
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- Novel synthesis of alkenes via triethylborane-induced free-radical reactions of alkyl iodides and β-nitrostyrenes
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Reactions of (E)-β-nitrostyrenes 1 and triethylborane 2 or tricyclohexylborane 4 in THF solution at room temperature in the presence of oxygen in the air as radical initiator generate high yields of trans-alkenes (E)-3 or (E)-5. Medium to high yields of d
- Liu,Jang,Shih,Hu,Chu,Yao
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p. 6021 - 6028
(2007/10/03)
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- One-pot synthesis of trans-β-alkylstyrenes
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One-pot synthesis of (E)-alkenes 5 from the reactions of aldehyde 1 and nitromethane 2 in the acetic acid solution and then with triethylborane 4 in the biphase of diethyl ether and aqueous solution in the presence of oxygen in air was reported. Various (E)-alkenes 7 could also be prepared when different kinds of secondary or tertiary alkyl iodides 6 were used under similar conditions.
- Liu, Ju-Tsung,Yao, Ching-Fa
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p. 6147 - 6150
(2007/10/03)
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- Free radical reactions to generate alkenes and/or ionic reactions to generate hydroximoyl chlorides when β-nitrostyrenes react with triethylaluminium or diethylaluminium chloride
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β-Nitrostyrenes 1 react with triethylaluminium or diethylaluminium chloride in diethyl ether solution and under nitrogen or argon to generate the alkenes 2 and the hydroximoyl chlorides 3 after work-up with ice-cold, cone, hydrochloric acid. The formation of the alkenes 2 is proposed to be a free-radical reaction via NO2/alkyl substitution since the yields of the alkenes 2 are increased in the presence of benzoyl peroxide (Bz2O2) and decreased in the presence of galvinoxyl. Only the alkenes 2 are produced with a high stereoselectivity for the E isomers when β-nitrostyrenes react with triethylaluminium in the presence of one to two equivalents of Bz2O2 as free-radical initiator. The mechanism of the generation of the hydroximoyl chlorides 3 is proposed to proceed through a 1,4-addition pathway to produce nitronates A, then the protonated nitronates B or the nitroso cations C are trapped by chloride ion to form the final products. The yields of compounds 3 are also improved by the presence of Lewis acids such as MgCl2. Medium to high yields of the hydroximoyl chlorides 3 and traces or low yields of the alkenes 2 are generated when triethylaluminium or diethylaluminium chloride react with β-nitrostyrenes in the presence of three equivalents of MgCl2 under argon.
- Chu, Cheng-Ming,Liu, Ju-Tsung,Lin, Wen-Wei,Yao, Ching-Fa
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- Free-Radical Reactions of Trialkylboranes with β-Nitrostyrenes to Generate Alkenes
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β-Nitrostyrenes 1 react with trialkylboranes under a nitrogen atmosphere to generate high yields of alkenes 2. The mechanism is proposed to be a free-radical reaction via NO2/alkyl substitution since the reaction is stimulated by the presence of a trace of oxygen in the nitrogen or tert-butyl peroxide or by photolysis and is retarded or inhibited by the addition of galvinoxyl to the solution.
- Yao, Ching-Fa,Chu, Cheng-Ming,Liu, Ju-Tsung
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p. 719 - 722
(2007/10/03)
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- An unexpected reaction between 2-aryl-1-nitro-1-alkenes and trialkylgallium compounds
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A novel reaction between 2-aryl-1-nitro-1-alkenes and trialkylgallium compound via NO2/alkyl substitution is found, and a possible mechanism is proposed.
- Han, Ying,Huang, Yao-Zeng,Zhou, Cheng-Ming
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p. 3347 - 3350
(2007/10/03)
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- Chemoselective reductive deoxygenation of α,β-unsaturated ketones and allyl alcohols
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A simple and convenient procedure for a highly chemoselective reductive deoxygenation of α,β-unsaturated ketones and allyl alcohols to olefins by sodium cyanoborohydride and boron trifluoride etherate in dry THF is described.
- Srikrishna, Adusumilli,Viswajanani, Ranganathan,Sattigeri, Jitendra A.,Yelamaggad, Channabasaveshwar V.
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p. 2347 - 2350
(2007/10/02)
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- Stereochemistry of direct olefin formation from carbonyl compounds and lithiated heterocyclic sulfones
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The conditions for the title reaction were studied for the 2-benzothiazole and 2-pyridine series and for some examples in the 2-pyrimidine series.The olefin preparations were generally observed to be more efficient for 2-BT-sulfone systems.From the data of the hundred cases studied, it can be concluded that (E)-olefins are obtained: (i) from saturated BT-sulfones and aromatic aldehydes; and (ii) from benzylic BT-sulfones and branched saturated aldehydes (isobutyraldehyde, pivalaldehyde) or α,β-ethylenic or aromatic aldehydes. (Z)-olefins arise: (i) fom propargylic BT-sulfones and saturated or aromatic aldehydes; and (ii) from allylic or benzylic Pyr-sulfones and saturated aldehydes.Possible mechanisms for this new olefination procedure were examined. - heteroaromatic sulfones, organolithium derivatives, intramolecular ipso reactions, stereochemistry, elimination, olefination.
- Baudin, J. B.,Hareau, G.,Julia, S. A.,Lorne, R.,Ruel, O.
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p. 856 - 878
(2007/10/02)
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- Protonation and Alkykation of 1-Arylpropenyl-lithium
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The protonation and alkylation of 1-arylpropenyl-lithium (1a-c) in ether was undertaken systematically; the regio- and stereo-chemistry being influenced by various factors.The characteristic features are as follows. (a) Protonation occurs predominantly at C-3, whereas the sterically more crowded C-1 is the more favoured site for alkylation, and (b) although 1-arylpropenyl-lithium (1) seems to exist mainly as the E-isomer, in some cases the product (3) or (5) having the Z-configuration is produced from attack at C-3 in a significant amount together with the E-isomer, e.g. protonation by oxygen acids in the presence or absence of tetramethylethylenediamine and methylation of the p-methoxy derivative (1a).
- Tanaka, Jiro,Nojima, Masatomo,Kusabayashi, Shigekazu,Nagase, Shigeru
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p. 673 - 678
(2007/10/02)
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- REACTIONS EN MILIEU HETEROGENE SOLIDE-LIQUIDE FAIBLEMENT HYDRATE III - LA REACTION DE WITTIG DANS LE SYSTEME CARBONATES ALCALINS/SOLVANT ORGANIQUE PROTIQUE
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The use of alkaline carbonates in a slighty hydrated solid-liquid protic organic media allowed the synthesis of alkenes from polyfunctional aldehydes with high yield in a E preferential stereochemistry specially with non-stabilized ylides.It has been shown that the decomposition of the threo betain acts as the determining step of the reaction.
- Le Bigot, Y.,El Gharbi, R.,Delmas, M.,Gaset, A.
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p. 3813 - 3824
(2007/10/02)
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