- Formation of allylated quaternary carbon centers: Via C-O/C-O bond fragmentation of oxalates and allyl carbonates
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Disclosed herein emphasizes Fe-promoted cross-electrophile allylation of tertiary alkyl oxalates with allyl carbonates that generates all C(sp3)-quaternary centers. The reaction involves fragmentation of tertiary alkyl oxalate C-O bonds to give tertiary alkyl radical intermediates, addition of the radicals to less hindered alkene terminals, and subsequent cleavage of the allyl C-O bonds. Allylation with 2-aryl substituted allyl carbonates was mediated by Zn/MgCl2, and Fe is used to promote the radical addition efficiency. By introduction of activated alkenes, a three-component radical cascade reaction took place.
- Chen, Haifeng,Ye, Yang,Tong, Weiqi,Fang, Jianhui,Gong, Hegui
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- P-Chiral Monophosphorus Ligands for Asymmetric Copper-Catalyzed Allylic Alkylation
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Asymmetric copper-catalyzed allylic alkylation between allyl bromides and alkyl Grignard reagents using a P-chiral monophosphorus ligand is described. A range of terminal olefins bearing tertiary or quaternary carbon centers were formed in good branched/linear selectivities and excellent enantioselectivities at copper loadings as low as 0.5 mol %.
- Xiong, Wenrui,Xu, Guangqing,Yu, Xinhong,Tang, Wenjun
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p. 4003 - 4013
(2019/06/24)
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- Method for synthesizing cis-olefin by catalyzing decarboxylation coupling reaction of NHP ester and aryl-terminated alkyne with iridium
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The invention provides a method for synthesizing Z-selective olefin by catalyzing a decarboxylation coupling reaction of an NHP ester and aryl-terminated alkyne with iridium. The aryl-terminated alkyne and its derivative and the NHP ester undergo a one-po
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Paragraph 0088-0089; 0099; 0101
(2019/02/13)
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- Selective Syntheses of Z-Alkenes via Photocatalyzed Decarboxylative Coupling of N-Hydroxyphthalimide Esters with Terminal Arylalkynes
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A novel, efficient Z-alkene synthesis via photocatalyzed decarboxylative couplings between terminal aryl alkynes and alkyl N-hydroxyphthalimide (NHPI) esters, which are derived from aliphatic carboxylic acids, is described. A wide range of primary, secondary, and tertiary carboxylates as well as α-amino acid and α-oxyacid-derived esters were employed as suitable substrates. The mild reaction conditions, broad substrate scope, functional group tolerance, and operational simplicity make this decarboxylative coupling reaction a valuable method in organic syntheses.
- Dai, Guo-Li,Lai, Shu-Zhen,Luo, Zhuangzhu,Tang, Zhen-Yu
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supporting information
p. 2269 - 2272
(2019/04/10)
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- Photo-induced Decarboxylative Heck-Type Coupling of Unactivated Aliphatic Acids and Terminal Alkenes in the Absence of Sacrificial Hydrogen Acceptors
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1,2-Disubstituted alkenes such as vinyl arenes, vinyl silanes, and vinyl boronates are among the most versatile building blocks that can be found in every sector of chemical science. We herein report a noble-metal-free method of accessing such olefins through a photo-induced decarboxylative Heck-type coupling using alkyl carboxylic acids, one of the most ubiquitous building blocks, as the feedstocks. This transformation was achieved in the absence of external oxidants through the synergistic combination of an organo photo-redox catalyst and a cobaloxime catalyst, with H2 and CO2 as the only byproducts. Both control experiments and DFT calculations supported a radical-based mechanism, which eventually led to the development of a selective three-component coupling of aliphatic carboxylic acids, acrylates, and vinyl arenes. More than 90 olefins across a wide range of functionalities were effectively synthesized with this simple protocol.
- Cao, Hui,Jiang, Heming,Feng, Hongyu,Kwan, Jeric Mun Chung,Liu, Xiaogang,Wu, Jie
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supporting information
p. 16360 - 16367
(2018/11/27)
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- Iron-Catalyzed Vinylic C?H Alkylation with Alkyl Peroxides
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A variety of alkyl peresters and alkyl diacyl peroxides, which are readily accessible from carboxylic acids, are utilized as general primary, secondary, and tertiary alkylating reagents for iron-catalyzed vinylic C?H alkylation of vinyl arenes, dienes, and 1,3-enynes. This transformation affords olefinic products in up to 98 % yield with high E/Z values. A broad range of functionalities, including carboxyl, boronic acid, methoxy, ester, amino, and halides, are tolerated. This protocol provides a facile approach to some olefins that are difficult to access, and hence, offers an alternative to existing systems. The synthetic utility of this method is demonstrated by late-stage functionalization of selected natural-product derivatives.
- Ge, Liang,Jian, Wujun,Zhou, Huan,Chen, Shaowei,Ye, Changqing,Yu, Fei,Qian, Bo,Li, Yajun,Bao, Hongli
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supporting information
p. 2522 - 2528
(2018/08/01)
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- Visible Light-Induced Room-Temperature Heck Reaction of Functionalized Alkyl Halides with Vinyl Arenes/Heteroarenes
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The first visible light-induced Pd-catalyzed Heck reaction of α-heteroatom substituted alkyl iodides and -bromides with vinyl arenes/heteroarenes has been developed. This transformation efficiently proceeds at room temperature and enables synthesis of valuable functionalized allylic systems, such as allylic silanes, boronates, germanes, stannanes, pivalates, phosphonates, phthalimides, and tosylates from the corresponding α-substituted methyl iodides. Notably, synthesis of the latter substrates failed under existing thermally induced Pd-catalyzed conditions, which highlights the importance of visible light for this transformation.
- Kurandina, Daria,Parasram, Marvin,Gevorgyan, Vladimir
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supporting information
p. 14212 - 14216
(2017/10/13)
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- Nickel-Catalyzed Reductive Allylation of Tertiary Alkyl Halides with Allylic Carbonates
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The construction of all C(sp3) quaternary centers has been successfully achieved under Ni-catalyzed cross-electrophile coupling of allylic carbonates with unactivated tertiary alkyl halides. For allylic carbonates bearing C1 or C3 substituents, the reaction affords excellent regioselectivity through the addition of alkyl groups to the unsubstituted allylic carbon terminus. The allylic alkylation method also exhibits excellent functional-group compatibility, and delivers the products with high E selectivity.
- Chen, Haifeng,Jia, Xiao,Yu, Yingying,Qian, Qun,Gong, Hegui
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p. 13103 - 13106
(2017/09/19)
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- Hydroalkylation of terminal aryl alkynes with alkyl diacyl peroxides
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A photo and nickel co-catalyzed hydroalkylation of terminal aryl alkynes enabled Z-preferred olefin synthesis has been developed under mild conditions. Alkyl diacyl peroxides were utilized as a new type of alkylation reagents and afforded Z-olefins as the major products in moderate to good yields.
- Li, Yougui,Ge, Liang,Qian, Bo,Babu, Kaki Raveendra,Bao, Hongli
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supporting information
p. 5677 - 5680
(2016/11/28)
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- Palladium-catalyzed intermolecular Heck reaction of alkyl halides
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Intermolecular Heck reaction of common alkyl halides, a longstanding problem in palladium catalysis, is realized with a simple Pd/dppf catalyst. Both primary and secondary alkyl halides are suitable for coupling with aromatic olefins. Single electron transfer from (dppf)Pd0 to alkyl halide initiated the catalytic cycle and gave alkyl radicals. This journal is the Partner Organisations 2014.
- Zou, Yinjun,Zhou, Jianrong
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supporting information
p. 3725 - 3728
(2014/04/03)
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- Selective formation of non-conjugated olefins by samarium(II)-mediated elimination/isomerization of allylic benzoates
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Aromatic allylic benzoates can be selectively transformed to the corresponding benzoate eliminated olefin by the action of samarium diiodide. Depending on the substrate and the elimination conditions, high selectivity for the non-conjugated alkene product
- Schaefer, Sara L.,Roberts, Connor L.,Volz, Erasmus O.,Grasso, Monika R.,O'Neil, Gregory W.
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p. 6125 - 6128
(2013/10/22)
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- Cross-coupling of grignard reagents with sulfonyl-activated sp3 carbon-nitrogen bonds
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Sulfonyl-activated sp3 carbon-nitrogen bonds have been found to be cleaved by Grignard reagents in the presence of 5 mol% of copper(I) iodide (CuI). Significantly, a broad range of sulfonyl-activated benzylic, allylic, and propargylic amines smoothly undergo the cross-coupling reaction with Grignard reagents to afford structurally diverse coupling products in good to excellent yields and with high chemo-, regio-, and stereoselectivity. Moreover, an S N2 mechanism has been demonstrated to be involved in the cross-coupling reaction that allows the asymmetric synthesis of chiral hydrocarbons from optically active α-branched amine derivatives. Copyright
- Li, Man-Bo,Tang, Xiang-Ling,Tian, Shi-Kai
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experimental part
p. 1980 - 1984
(2011/10/12)
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- Copper-free asymmetric allylic alkylation with grignard reagents
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(Chemical Equation Presented) Open wide and say AAA: The copper-free asymmetric allylic alkylation reaction of Crignard reagents, catalyzed by N-heter-ocyclic carbenes, is reported for allyl bromide derivatives. This reaction offers good enantioselectivit
- Jackowski, Olivier,Alexakis, Alexandre
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supporting information; experimental part
p. 3346 - 3350
(2010/07/15)
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- Silaheterocycles, XXIII. - Synthesis and Thermolysis Reactions of Si-Functionalized 2-Silaazetidines
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Dichloroneopentylsilene (1) is formed in situ by the reaction of trichlorovinylsilane with LitBu.The cycloaddition to imines yields Si,Si-dichloro-functionalized 2-silaazetidines in a preparative scale.With aldimines as trapping agents for 1, the resulting SiN four-membered ring compounds are isolated as syn/anti-isomers (e.g. syn/anti-15 and -16; syn/anti ca. 2:1).Silene 1 is not liberated from the silaazetidines on heating, but the Si,Si-dichloro-substituted silanimine Cl2Si=NtBu (24) is formed.This can be trapped by Me3SiOMe or Ph2C=NtBu to give the addition products 25 and 26, respectively.The pathways are discussed which lead to stereoisomeric SiN ring compounds by a multiple-step mechanism including zwitterionic intermediates (1,4-dipoles).In addition there is strong evidence for the formation of 1, depending on the trapping reagent used.This fact may be explained by donor->silene interactions.The thermolysis products of silaazetidines support the formulation of a stepwise decomposition to an alkene and Cl2Si=NR derivatives. Key Words: Silene, dichloroneopentyl- / Imines / Cycloaddition reactions / 2-Silaazetidines / Thermolysis reactions
- Auner, Norbert,Weingartner, Armin W.,Bertrand, Guy
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p. 581 - 590
(2007/10/02)
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- OLEFINATION OF ALDEHYDES WITH TETRAALKYL-GEM-DIALUMOALKANES
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A new method of cis-olefination, based on the reaction of aldehydes with geminal alumolithium reagents, is proposed.
- Kuchin, A. V.,Markova, S. A.,Gorobets, E. V.,Tolstikov, G. A.
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p. 1034 - 1037
(2007/10/02)
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- Silaheterocycles VII; Reactions of Dichloroneopentylsilene with Aldehydes
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Dichloroneopentylsilene, Cl2Si=CHCH2But (1), is produced from vinyltrichlorsilane (2) and LiBut in n-pentane at -78 deg C.The reactions of 1 with aromatic aldehydes like benzaldehyde and the 4-methoxy- or 4-fluoro-substituted derivatives, naphthalene-1 and -2- and 9-anthracenecarbaldehyde, furfurale and its S-analogous thiophene carbaldehyde yield 1,2-silaoxetanes by cycloaddition with the carbonyl group.The same is true for the reactions of 1 with pivaline-, butyr- and acetaldehyde.The silaoxetanes cannot be isolated; the formation of dichlorovinylsiloxanes and the olefinic compounds R-CH=CH-CH2But suggests that the cycloreversion of the Si-O four-membered ring competes with an intramolecular isomerization, evidently via formation of a zwitterionic intermediate R-C+HOSiCl2C-HCH2But.The product formation by coupling reactions of lithiated aldehydes and 2 is excluded by performing analogous reactions with the chlorosilanes Me2SiCl(R) (R=Cl, Me, Vi).
- Auner, Norbert,Seidenschwarz, Claudia
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p. 909 - 920
(2007/10/02)
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- Electron-transfer processes. 43. Attack of alkyl radicals upon 1-alkenyl and 1-alkynyl derivatives of tin and mercury
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Alkyl radicals, obtained by reaction of Bu3Sn? or ClHg? with alkylmercury halides, will undergo regioselective and in some cases stereospecific substitution by a free radical chain addition-elimination mechanism with 1-alkenylstannanes or -mercurials. The chain reaction is also observed for 1-alkynyl derivatives and in the photostimulated demercuration of mixed alkyl and 1-alkenyl- or 1-alkynylmercurials. Chain propagation with alkyl radical formation is also observed to occur in the reactions of β-eliminated ClHg? with Grignard reagents in PhH-THF solution. In competitive reactions of Bu3Sn? or ClHg? with pairs of alkylmercury chlorides, it is observed that a tert-butylmercurial is >1000 times more reactive than a n-butylmercurial, suggesting a concerted dissociate electron-transfer process not involving the intermediacy of RHg? species.
- Russell, Glen A.,Ngoviwatchai, Preecha,Tashtoush, Hasan I.
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p. 696 - 702
(2008/10/08)
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- Cross-Coupling Reaction of tert-Alkyl halides with Grignard Reagents in Dichloromethane as a Non-Lewis Basic Medium
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In dichloromethane as a non-Lewis basic solvent, 1-haloadamantane 1 underwent a cross-coupling reaction with Grignard reagents to give bridgehead-substituted products 3-16 in moderate yields.In this case the same kind of halogen in both 1 and a Grignard reagent was favored; if not, functional exchange (i.e., 1a to 1c) occurred first.The reaction using 5-hexenylmagnesium bromide as a radical probe afforded uncyclized/cyclized coupling products in a 6/4 ratio.These fact suggested the significant participation of the single-electron-transfer process in these reactions.The present method could be extended to tert-butylation with some Grignard reagents.Interestingly, 1,3-dichloro-3-methylbutane coupled with butylmagnesium chloride selectively at the tertiary position. for the above displacement reaction of 1, an organozinc was also found to be effective.
- Ohno, Masatomi,Shimizu, Kazuo,Ishizaki, Kenichi,Sasaki, Tadashi,Eguchi, Shoji
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p. 729 - 733
(2007/10/02)
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- Reaction of Phenyl-Substituted Allyllithiums with tert-Alkyl Bromides. Remarkable Difference in the Alkylation Regiochemistry between a Polar Process and the One Involving Single-Electron Transfer
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The reaction of phenyl-substituted allyllithiums 1a-h with tert-alkyl bromides was investigated systematically.The alkylation regiochemistry was influenced in a complicated fashion by various factors including substituent effects, both steric and electronic, solvents, and the presence of strongly coordinating additives, tetramethylethylenediamine and hexamethylphosphoramide.On the basis of the cyclizable probe experiments, the observed regiochemistry was interpreted as follows. (a) The reaction proceeds by two alternative pathways, a polar one and single electron transfer (SET), the extent of each path being influenced by the variable factors and (b) a polar pathway favors coupling at the phenyl-substituted site (C-1), while in the case of SET the C-C bond formation occurs predominantly at the site far from the phenyl substituent (C-3).
- Tanaka, Jiro,Nojima, Masatomo,Kusabayashi, Shigekazu
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p. 3391 - 3397
(2007/10/02)
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- Reaction of 1-Arylpropenyl-lithium with t-Alkyl Bromides. The Influence of Substituent Electronic Effects and Additives on the Course of the Reaction
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The reaction of 1-arylpropenyl-lithium (1a-c) with t-alkyl bromides proceeds by either a nucleophilic substitution or single electron transfer mechanism, the preferred pathway being a function of electronic substituent effects and the absence or presence of tetramethylethylenediamine or hexamethylphosphoramide.
- Tanaka, Jiro,Nojima, Masatomo,Kusabayashi, Shigekazu
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p. 242 - 244
(2007/10/02)
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- Reaction of 1-Aryl-3-chloropropenes with Grignard Reagents. Nucleophilic Substitution versus Single-electron Transfer
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The reactions of ambident 1-aryl-3-chloropropenes (1a-e) with a series of Grignard reagents, R'MgY (R' = Me, Pr, Ph, Pri, But; Y = Br, I), were carried out in diethyl ether (EE) and tetrahydrofuran (THF).The products were a mixture of two alkylation products (2) and (3), and three dimerization products (4)-(6).The alkylation:dimerization ratio and the composition of the two alkylation products were a marked function of substituent electronic effects in the chlorides (1a-e), R' or Y of R'MgY, and solvent.On the basis of the stereochemistry of alkylation, cyclizable probe experiments, and the effect of the addition of FeCl3 on product composition, the following conclusions were obtained.First, dimers (4)-(6) are most likely to be produced by a mechanism involving single-electron transfer (SET).Second, for the formation of alkylation products (2) and (3), three alternative pathways contribute depending on the nature of R'MgY and solvent, (a) competitive SN2-SN2' pathways in the reaction of R'MgBr in EE, (b) a process involving SET in the reaction with R'MgI in EE, and (c) SN2 pathways in the reaction of R'MgBr in THF.
- Muraoka, Kiyoshige,Nojima, Masatomo,Kusabayashi, Shigekazu,Nagase, Shigeru
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p. 761 - 768
(2007/10/02)
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- Boration Reactions with 1-Alkynes
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Halodiorganoboranes R2BHal(R = Et, Ph) as well as benzyldihaloboranes PhCH2BHal2 undergo a regiospecific addition to the triple-bond of 1-alkynes ACCR'.The reversible haloboration (1) gives Z-alkenes as the more stable isomers.At elevated temperatures, the irreversible 1,1-organoboration (2) predominates, accompanied by a 1,2-transfer of A, whereas the 1,2-organoboration (3) is observed only as an unimportant side-reaction in a few cases.The cyclisation (4) occurs as a sequence of cis-haloboration and intramolecular aromatic alkenylation in the case of PhCH2BCl2 as borating agent.
- Binnewirtz, Ralf-Juergen,Klingenberger, Helmut,Welte, Rainer,Paetzold, Peter
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p. 1271 - 1284
(2007/10/02)
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