- Aryl C-F bond functionalization preparation method
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The invention relates to the technical field of organic compound synthesis, in particular to an aryl C-F bond functionalization preparation method. A fluorobenzene compound and a nucleophilic reagent react under the action of a composite catalyst, wherein the composite catalyst is formed by mixing a visible light catalyst and a metal catalyst. The photocatalyst is adopted, the reaction process is safe and controllable, and operation in the preparation and production process is simplified; a purple LED is used as a reaction energy source and is green and environment-friendly, the energy utilization rate is high, and conversion from light energy to chemical energy can be efficiently realized; in the reaction, a simple nucleophilic reagent is used for attacking free radical cation species generated under a visible light catalysis condition, so that a target product with an extremely wide range is efficiently and greenly prepared; the operation steps are simplified, and the reaction route is shortened; and moreover, the forward reaction rate is high, and the production efficiency is remarkably improved.
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Paragraph 0052; 0054-0057
(2021/09/29)
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- Manganese catalyzed dehydrogenative silylation of alkenes: Direct access to allylsilanes
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Dehydrogenative silylation of alkenes with silanes to produce allylsilanes is achieved through manganese catalysis with a wide scope of substrate tolerance. This transformation involves silane radicals initiated by manganese complex without additional oxidant additives. It offers a general, convenient and practical protocol with excellent functional group compatibility and gram-scale capacity for the modular synthesis of allylsilanes.
- Wu, Shang,Zhang, Ying,Jiang, Hongyan,Ding, Ning,Wang, Yanbin,Su, Qiong,Zhang, Hong,Wu, Lan,Yang, Quanlu
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supporting information
(2020/06/03)
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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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- SO2 conversion to sulfones: Development and mechanistic insights of a sulfonylative Hiyama cross-coupling
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A Pd-catalyzed Hiyama cross-coupling reaction using SO2 is described. The use of silicon-based nucleophiles leads to the formation of allyl sulfones under mild conditions with a broad functional group tolerance. Control experiments coupled with DFT calculations shed light on the key steps of the reaction mechanism, revealing the crucial role of a transient sulfinate anion.
- Adenot, Aurélien,Char, Jo?lle,Von Wolff, Niklas,Lefèvre, Guillaume,Anthore-Dalion, Lucile,Cantat, Thibault
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supporting information
p. 12924 - 12927
(2019/11/05)
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- Controllable, Sequential, and Stereoselective C-H Allylic Alkylation of Alkenes
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The direct conversion of C-H bonds into new C-C bonds represents a powerful approach to generate complex molecules from simple starting materials. However, a general and controllable method for the sequential conversion of a methyl group into a fully substituted carbon center remains a challenge. We report a new method for the selective and sequential replacement of three C-H bonds at the allylic position of propylene and other simple terminal alkenes with different carbon groups derived from Grignard reagents. A copper catalyst and electron-rich biaryl phosphine ligand facilitate the formation of allylic alkylation products in high branch selectivity. We also present conditions for the generation of enantioenriched allylic alkylation products in the presence of catalytic copper and a chiral phosphine ligand. With this approach, diverse and complex products with substituted carbon centers can be generated from simple and abundant feedstock chemicals.
- Qin, Ling,Sharique, Mohammed,Tambar, Uttam K.
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supporting information
p. 17305 - 17313
(2019/11/03)
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- Palladium-Catalyzed Oxidative Allylation of Sulfoxonium Ylides: Regioselective Synthesis of Conjugated Dienones
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The first examples of palladium-catalyzed allylic C-H oxidative allylation of sulfoxonium ylides to afford the corresponding conjugated dienones with moderate to good yields have been established. The features of this novel conversion include mild reaction conditions, wide substrate scope, and excellent regioselectivity.
- Li, Chunsheng,Li, Meng,Zhong, Wentao,Jin, Yangbin,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 872 - 875
(2019/05/16)
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- Method for preparing allyl compound
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The invention relates to a method for preparing an allyl compound, and the specific steps are as follows: (1) allyl acetate, a halogenated hydrocarbon, magnesium chips, an additive, a catalyst and a ligand are dissolved in a solvent and mixed, and a crude product is obtained after reaction; and (2) after the crude product obtained in the step (1) is subjected to separation and purification, the allyl compound is obtained. Compared with the prior art, the preparation method effectively avoids the use of a pre-formed organometallic reagent in a traditional synthetic method, and has the characteristics of convenient operation, easy availability of raw materials, low cost, greenness, environmental friendliness and high yield.
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Paragraph 0028-0034
(2019/11/13)
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- Catalytic Oxidative Trifluoromethoxylation of Allylic C?H Bonds Using a Palladium Catalyst
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A catalytic intermolecular allylic C?H trifluoromethoxylation reaction of alkenes has been developed based on the use of a palladium catalyst, CsOCF3 as the trifluoromethoxide source, and benzoquinone as the oxidant. This reaction provides an efficient route for directly accessing allylic trifluoromethoxy derivatives with excellent regioselectivities from terminal alkenes via an allylic C?H bond activation process.
- Qi, Xiaoxu,Chen, Pinhong,Liu, Guosheng
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supporting information
p. 9517 - 9521
(2017/08/01)
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- Palladium-catalyzed oxidative allylation of bis[(pinacolato)boryl]methane: Synthesis of homoallylic boronic esters
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A palladium-catalyzed oxidative allylation of bis[(pinacolato)boryl]methane to afford the corresponding homoallylic organoboronic esters with moderate to excellent yields is reported. This novel transformation provides an efficient strategy for the construction of homoallylic organoboronic esters in one step with a broad substrate scope. It is proposed that the palladium-catalyzed oxidative allylic C-H bond activation process may be involved in the catalytic cycle.
- Li, Chunsheng,Li, Meng,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 66 - 69
(2017/12/27)
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- Palladium-Catalyzed Regioselective Allylation of Chloromethyl(hetero)arenes with Allyl Pinacolborate
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The palladium-catalyzed regioselective allylation reaction between chloromethyl(hetero)arenes and allyl pinacolborate is reported in this work. Chloromethylarenes smoothly reacted with allyl pinacolborate, producing para-allylated dearomatization products
- Zhang, Sheng,Ullah, Aziz,Yamamoto, Yoshinori,Bao, Ming
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supporting information
p. 2723 - 2728
(2017/08/23)
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- Anti-Markovnikov rearrangement in sulfur mediated allylic C-H amination of olefins
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Cationic rearrangement reactions usually follow Markovnikov's rule to give more substituted carbocations as stable intermediates. During our study on sulfur mediated allylic C-H amination of olefins, very rare cases of anti-Markovnikov rearrangement from secondary carbocations toward primary carbocations or primary triflates were observed.
- Zhang, Zhong,Du, Hongguang,Xu, Jiaxi,Li, Pingfan
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supporting information
p. 11547 - 11550
(2016/10/03)
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- Palladium-catalyzed aerobic oxidative double allylic C-H oxygenation of alkenes: A novel and straightforward route to α,β-unsaturated esters
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A mild tandem oxidative functionalization of allyl aromatic hydrocarbons was accomplished using the catalytic system of Pd(OAc)2/DMA under 1 atm O2. The green twofold C-O bond formation involving double allylic C-H oxygenation unlocks opportunities for markedly different synthetic strategies. Moreover, the reaction affords aryl α,β-unsaturated esters directly from readily available terminal olefins in moderate to good yields with excellent chemo- and stereoselectivities.
- Yang, Wanfei,Chen, Huoji,Li, Jianxiao,Li, Chunsheng,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 9575 - 9578
(2015/06/08)
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- Direct conversion of allyl arenes to aryl ethylketones via a TBHP-mediated palladium-catalyzed tandem isomerization-Wacker oxidation of terminal alkenes
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A TBHP-mediated palladium-catalyzed tandem isomerization-Wacker oxidation of terminal alkenes was developed. This methodology provides a new efficient and simple route for conversion of a range of allyl arenes directly into aryl ethylketones in good yields with high chemoselectivity.
- Zhao, Jinwu,Liu, Li,Xiang, Shijian,Liu, Qiang,Chen, Huoji
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supporting information
p. 5613 - 5616
(2015/05/27)
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- Trifluoromethylchlorosulfonylation of alkenes: Evidence for an inner-sphere mechanism by a copper phenanthroline photoredox catalyst
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Abstract A visible-light-mediated procedure for the unprecedented trifluoromethylchlorosulfonylation of unactivated alkenes is presented. It uses [Cu(dap)2]Cl as catalyst, and contrasts with [Ru(bpy)3]Cl2, [Ir(ppy)2(dtbbpy)]PF6, or eosin Y that exclusively give rise to trifluoromethylchlorination of the same alkenes. It is assumed that [Cu(dap)2]Cl plays a dual role, that is, acting both as an electron transfer reagent as well as coordinating the reactants in the bond forming processes. Double role: The trifluoromethylchlorosulfonylation of unactivated alkenes was developed using [Cu(dap)2]Cl as catalyst (dap=2,9-bis(para-anisyl)-1,10-phenanthroline). [Cu(dap)2]Cl plays a dual role; acting as an electron transfer reagent as well as coordinating the reactants in the bond forming processes.
- Bagal, Dattatraya B.,Kachkovskyi, Georgiy,Knorn, Matthias,Rawner, Thomas,Bhanage, Bhalchandra M.,Reiser, Oliver
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supporting information
p. 6999 - 7002
(2015/06/08)
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- AsCat and FurCat: New Pd catalysts for selective roomerature Stille cross-couplings of benzyl chlorides with organostannanes
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Two novel succinimide-based palladium complexes, AsCat and FurCat, are highly efficient catalysts for roomerature Stille cross-coupling of organostannanes with benzyl chlorides. The air- and moisture-stable catalysts are prepared in one step, and the coupling reactions proceed with a high selectivity for the benzyl position under mild conditions without the need for additives. This journal is
- Ronson, Thomas O.,Carney, Jonathan R.,Whitwood, Adrian C.,Taylor, Richard J. K.,Fairlamb, Ian J. S.
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supporting information
p. 3466 - 3469
(2015/03/04)
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- Palladium-catalyzed regioselective azidation of allylic C-H bonds under atmospheric pressure of dioxygen
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A palladium-catalyzed allylic azidation of alkenes with sodium azide under atmospheric pressure of dioxygen was developed. This methodology provides a new efficient and simple route for accessing allylic azides. Furthermore, the one-pot process consisting of Pd-catalyzed allylic azidation of alkenes and Cu-catalyzed 1,3-dipolar cycloaddition led directly to the 1,2,3-triazole from the alkene. The formed allylic azide can be also in situ reduced to the allylic amine or oxidized to the alkenyl nitrile. the Partner Organisations 2014.
- Chen, Huoji,Yang, Wanfei,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 3340 - 3343
(2014/05/20)
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- Iron phosphine catalyzed cross-coupling of tetraorganoborates and related group 13 nucleophiles with alkyl halides
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Iron phosphine complexes prove to be good precatalysts for the cross-coupling of alkyl, benzyl, and allyl halides with not only aryl triorganoborate salts but also related aluminum-, gallium-, indium-, and thallium-based nucleophiles. Mechanistic studies revealed that while Fe(I) can be accessed on catalytically relevant time scales, lower average oxidation states are not formed fast enough to be relevant to catalysis. EPR spectroscopic studies reveal the presence of bis(diphosphine)iron(I) complexes in representative catalytic reactions and related processes with a range of group 13 nucleophiles. Isolated examples were studied by M?ssbauer spectroscopy and single-crystal X-ray structural analysis, while the electronic structure was probed by dispersion-corrected B3LYP DFT calculations. An EPR study on an iron system with a bulky diphosphine ligand revealed the presence of an S = 1/2 species consistent with the formation of a mono(diphosphine)iron(I) species with inequivalent phosphine donor environments. DFT analysis of model complexes allowed us to rule out a T-shaped Fe(I) structure, as this is predicted to be high spin.
- Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Clifton, Jamie,Cogswell, Paul M.,Gower, Nicholas J.,Haddow, Mairi F.,Harvey, Jeremy N.,Kehl, Jeffrey A.,Murphy, Damien M.,Neeve, Emily C.,Neidig, Michael L.,Nunn, Joshua,Snyder, Benjamin E. R.,Taylor, Joseph
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p. 5767 - 5780
(2015/02/19)
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- Transition-metal-free arylations via photogenerated triplet 4-alkyl- and 4-trimethylsilylphenyl cations
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The irradiation in protic solvents of 4-chloroalkylbenzenes and 4-chlorophenyltrimethylsilane caused the heterolytic cleavage of aryl-chlorine bonds to give the corresponding triplet phenyl cations. These were exploited for transition-metal-free arylation reactions under mild conditions to give allylbenzenes, γ-benzyl lactones, 3-arylacetals (ketals), and biaryls in moderate to good yields. The path followed was supported by DFT calculations at the UB3LYP/6-311+G(2d,p) level.
- Qrareya, Hisham,Raviola, Carlotta,Protti, Stefano,Fagnoni, Maurizio,Albini, Angelo
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p. 6016 - 6024
(2013/07/26)
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- Method for Allylating and Vinylating Aryl, Heteroaryl, Alkyl, and Alkene Halogenides Using Transition Metal Catalysis
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What is described is a process for preparing organic compounds of the general formula (I) R—R′??(I) by converting a corresponding compound of the general formula (II) R—X ??(II) in which X is fluorine, chlorine, bromine or iodine to an organomagnesium compound of the general formula (III) [M+]n[RmMgXkY1]??(III) wherein compounds of the formula (III) are reacted with a compound of the general formula (IV) characterized in that the reaction of (III) with (IV) is performed in the presence of a) catalytic amounts of an iron compound, based on the compound of the general formula (II), and optionally in the presence of b) a nitrogen-, oxygen- and/or phosphorus-containing additive in a catalytic or stoichiometric amount, based on the compound of the general formula (II).
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Paragraph 0062; 0063; 0064
(2013/07/25)
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- α,n-didehydrotoluenes by photoactivation of (chlorobenzyl) trimethylsilanes: An alternative to enyne-allenes cyclization
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Doubly radical: A novel entry to ?,n-didehydrotoluene (DHT) diradicals is disclosed and proceeds through the photochemical activation of (chlorobenzyl)trimethylsilanes with chloride loss and elimination of the SiMe3+ group (see scheme). The products formed in solution are indicative of the intermediacy of the three isomers of the ?,n-DHT
- Protti, Stefano,Ravelli, Davide,Mannucci, Barbara,Albini, Angelo,Fagnoni, Maurizio
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supporting information; experimental part
p. 8577 - 8580
(2012/09/22)
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- Catalyst-free suzuki-type coupling of allylic bromides with arylboronic acids
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The coupling of arylboronic acids with electron-rich allylic bromides is accomplished in the absence of any transition-metal catalyst through conventional heating. The reaction is completely regioselective, affording only the α-coupled product, and can be carried out under mild aerobic conditions in an organic solvent; the presence of a base is required. Copyright
- Scrivanti, Alberto,Beghetto, Valentina,Bertoldini, Matteo,Matteoli, Ugo
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supporting information; experimental part
p. 264 - 268
(2012/02/04)
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- Practical iron-catalyzed allylations of aryl grignard reagents
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An operationally simple iron-catalyzed reductive cross-coupling reaction between aryl halides and allyl electrophiles has been developed. The underlying domino process exhibits high versatility with respect to the allylic leaving group (acetate, tosylate, diethyl phosphate, methyl carbonate, trimethylsilanolate, methanethiolate, chloride, bromide) and high economic and environmental sustainability with respect to the catalyst system (0.2-5 mol% tris(acetylacetonato)iron(III), ligand-free) and reaction conditions (tetrahydrofuran, 0°C, 45 min).
- Mayer, Matthias,Czaplik, Waldemar M.,Von Wangelin, Axel Jacobi
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supporting information; experimental part
p. 2147 - 2152
(2010/12/18)
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- Three-dimensional cubic mesoporous materials with a built-in N-heterocyclic carbene for Suzuki-Miyaura coupling of aryl chlorides and C(sp 3)-chlorides
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New cubic cage-like mesoporous materials with a bulky N-heterocyclic carbene [IPr, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] precursor in the framework were synthesized by a co-condensation of IPr precursor-bridged organosilane and TEOS in the presence of template. N2 sorption, XRD and TEM characterizations revealed that the mesostructural orderings of the synthesized materials depended on the molar fraction of the bridged organosilane in the initial gel mixture. With the increase in the molar fraction of the organosilane from 2.5% to 15%, the mesostructure of the synthesized material changed from a well-ordered 3D ordered structure to a amorphous structure. FT-IR and solid-state NMR characterizations confirmed that IPr carbene precursor was covalently integrated with the solid materials. Such hybrid materials were able to coordinate Pd(acac)2, leading to active solid catalysts for Suzuki-Miyaura couplings of less reactive aryl chlorides. The solid catalyst could be reused 8 times without a significant decrease in activity. Furthermore, the solid catalyst was active for the coupling of C(sp3)-chlorides and arylboronic acids.
- Yang, Hengquan,Li, Guang,Ma, Zhancheng,Chao, Jianbin,Guo, Zhiqiang
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experimental part
p. 123 - 133
(2011/02/24)
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- Efficient double bond migration of allylbenzenes catalyzed by Pd(OAc) 2-HFIP system with unique substituent effect
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A novel catalyst system of Pd(OAc)2-HFIP induces double-bond migration of allylbenzenes under mild conditions with low catalytic loading to afford 1-propenylbenzenes. The reaction shows a unique substituent effect that is highly dependent on the distance of substituents from the allylic moiety. Thus, the reactivity of substrates bearing a methyl group is ordered in para > meta > ortho, whereas it is entirely reversed as ortho > meta > para for methoxy and chloro substituents.
- Nishiwaki, Nagatoshi,Kamimura, Ryuichiro,Shono, Kimihiro,Kawakami, Toshihiko,Nakayama, Katsuhisa,Nishino, Kohei,Nakayama, Takayuki,Takahashi, Keisuke,Nakamura, Aki,Hosokawa, Takahiro
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supporting information; experimental part
p. 3590 - 3592
(2010/08/19)
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- Palladium complexes with a tridentate PNO ligand. Synthesis of η1-allyl complexes and cross-coupling reactions promoted by boron compounds
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The iminophosphine 2-(2-Ph2P)C6H4NCHC 6H4OH (P-N-OH) reacts with [Pd(μ-Cl)(η3- C3H5)]2 yielding [PdCl(P-N-O)] and propene. In the presence of NEt3, the reaction of P-N-OH with [Pd(μ-Cl)(η3-1-R1,3-R2C 3H3)]2 (R1 = R2 = H, Ph; R1 = H, R2 = Ph) affords the η1-allyl derivatives [Pd(η1-1-R1,3-R2C 3H3)](P-N-O)] (R1 = R2 = H: 1; R1 = H, R2 = Ph: 2; R1 = R2 = Ph: 3). In solution, the complexes 1 and 3 undergo a slow dynamic process which interconverts the bonding site of the allyl ligand. The X-ray structural analysis of 1 indicates a square-planar coordination geometry around the palladium centre with a P,N,O,-tridentate ligand and a σ bonded allyl group. The complexes [PdR(P-N-O)] (R = C6H4Me-4, CCPh) react slowly with p-bromoanisole in the presence of p-tolylboronic acid to give [PdBr(P-N-O)] and the coupling product RC6H4OMe-4. The latter reactions also proceed at a low rate under catalytic conditions. The coupling of allyl bromide with p-tolylboronic acid is catalyzed by [PdCl(P-N-O)]/K2CO3 to give 4-allyltoluene.
- Crociani, Bruno,Antonaroli, Simonetta,Burattini, Marcello,Paoli, Paola,Rossi, Patrizia
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experimental part
p. 3665 - 3672
(2010/06/17)
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- Introduction of allyi and prenyl side-chains into aromatic systems by suzuki cross-coupling reactions
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This paper reports some studies aiming at the developement of a general protocol useful for the synthesis of allyl- and prenylaromatic compounds. The first part deals with, the preparation of boron reagents like arylboronic acids and their pinacol esters as well as of pinacol allyl- and prenylboronates. The second part of the paper is devoted to the use of these boron reagents in Suzuki-Miyaura cross-coupling reactions leading to allylation and prenylation of aromatic compounds. Of the six methods studied, the most promising re-suits were obtained by using the Pd2(dba)3-catalyzed reactions of arylboronic acids with allyl and prenyl bromides, that lead to the products of cross coupling in high yields (average 87%), and the reactions of aryl trifluoroborates with allyl and prenyl bromides catalyzed by Pd(OAc)2 that lead to the products of coupling in all cases in high yields (average 82%).
- Gerbino, Dario C.,Mandolesi, Sandra D.,Schmalz, Hans-Guenther,Podesta, Julio C.
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experimental part
p. 3964 - 3972
(2010/02/27)
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- Sodium dithionite initiated addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to allylaromatics. Facile synthesis of conjugated dienes substituted with terminal CF3 group
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Sodium dithionite effectively promotes the addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to the terminal double bond of allylbenzenes 1. The reactions proceeded in MeCN/H2O to give a 3:1 mole ratio of diastereoisomers of 1-(2-bromo-4-chloro-5,5,5-trifluoropentyl)benzenes 2 as the main products together with small amounts of its reductive debromination products 3. Total yields of 2 and 3 were dependent on the nature of the aromatic ring substituents in 1. Treatment of adducts 2 with DBU in refluxing hexanes resulted in double dehydrohalogenation affording, in good yields, conjugated dienes 4 (1,1,1-trifluoro-5-phenyl-2,4-pentadienes) terminated with the CF3 group at the one end and the phenyl group at the opposite end. These dienes were found to be sufficiently reactive to undergo Diels-Alder condensation with active dienophiles to give trifluoromethylated carbocycles. The reactions of CF3CHClBr with allylheterocycles were less successful and lead to low yields of mixtures of hardly separable compounds or to polymeric resins.
- Ignatowska, Jolanta,Dmowski, Wojciech
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p. 720 - 729
(2008/03/28)
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- Biocatalytic racemization of (hetero)aryl-aliphatic α- hydroxycarboxylic acids by Lactobacillus spp. proceeds via an oxidation-reduction sequence
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The biocatalytic racemization of a range of (hetero)aryl- and (di)aryl-aliphatic α-hydroxycarboxylic acids has been achieved by using whole resting cells of Lactobacillus spp. The essentially mild (physiological) reaction conditions ensure the suppression of undesired side reactions, such as elimination, decomposition or condensation. Cofactor/inhibitor studies using a cell-free extract of Lactobacillus paracasei DSM 20207 reveal that the addition of redox cofactors (NAD+/NADH) leads to a distinct increase in the racemization rate, while strong inhibition is observed in the presence of Thio-NAD+, which suggests that the racemization proceeds by an oxidation-reduction sequence rather than involvement of a "racemase" enzyme. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Nestl, Bettina M.,Glueck, Silvia M.,Hall, Melanie,Kroutil, Wolfgang,Stuermer, Rainer,Hauer, Bernhard,Faber, Kurt
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p. 4573 - 4577
(2007/10/03)
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- A highly effective (Triphenyl phosphite)palladium catalyst for a cross-coupling reaction of allylic alcohols with organoboronic acids
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The cross coupling reaction of aryl and vinyl boronic acids and allylic alcohols proceeded smoothly in toluene or dioxane in the presence of a (triphenyl phosphite)palladium catalyst to give the corresponding allylbenzene derivatives and 1,4-dienes. Neither cocatalysts for promoting C-O bond cleavage of allylic alcohols nor bases for activation of organoboron reagents are required for promoting the coupling process. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Kayaki, Yoshihito,Koda, Takashi,Ikariya, Takao
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p. 4989 - 4993
(2007/10/03)
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- Solventless Suzuki coupling reactions on palladium-doped potassium fluoride alumina
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A solventless Suzuki coupling reaction has been developed which utilizes a commercially available potassium fluoride alumina mixture and palladium powder. The new reaction is convenient, environmentally friendly, and generates good yields of the coupled products. Aryl iodides react faster than the bromides or chlorides; aryl groups are also more reactive than alkenyl groups, which react faster than alkyl groups. The use of microwave irradiation accelerates the reaction, decreasing reaction times from hours to minutes. The palladium powder catalyst can be recycled using a simple filtration and washing sequence without loss of catalytic activity.
- Kabalka, George W.,Wang, Lei,Pagni, Richard M.,Hair, C. Maxwell,Namboodiri, Vasudevan
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p. 217 - 222
(2007/10/03)
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- o-Nitroaryldioxolane for protection of pheromones. Study of the photodelivery of carbonylic compounds
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o-Nitrophenyldioxolanes 1 to 12 have been prepared and the rate of their photocleavage determined Steric congestion in the molecule causes a decrease of the reaction rate. The decrease in the rate is especially important in the presence of a nitro group in a second phenyl ring.
- Ceita, Luisa,Maiti, Amiya K.,Mestres, Ramon,Tortajada, Amparo
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p. 1023 - 1055
(2007/10/03)
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- Cross-coupling reactions of hypervalent siloxane derivatives: An alternative to stille and Suzuki couplings
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Palladium-catalyzed cross-coupling of phenyl, vinyl, and allyl siloxane derivatives proceeded in good to excellent yield with aryl iodides, electron-deficient aryl bromides, and allylic benzoates. Methyl and 2,2,2-trifluoroethyl siloxane derivatives can be employed in the coupling reaction. Electron-donating and -withdrawing groups are tolerated on the aryl halide without affecting the coupling. The scope and limitations of this alternative to Stille and Suzuki couplings is outlined.
- Mowery, Molly E.,DeShong, Philip
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p. 1684 - 1688
(2007/10/03)
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- Molybdenum- and tungsten-catalyzed allylation of aromatic compounds with allylic esters and alcohols
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A novel method to substitute aromatic compounds with allylic groups using oxygen-containing allylic compounds in the presence of molybdenum or tungsten carbonyls under neutral conditions has been developed. The method is applicable to one step synthesis of methyl eugenol.
- Shimizu, Isao,Sakamoto, Toshiaki,Kawaragi, Saeko,Maruyama, Yooichiro,Yamamoto, Akio
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p. 137 - 138
(2007/10/03)
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- Novel coupling reaction of pentaarylantimony with carbon electrophiles
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The cross-coupling reactions of pentaarylantimony with organic halides and allyl acetate were studied under various conditions of acetonitrile solvent, palladium catalysts and copper iodide. Acetonitrile solvent enabled a nucleophilic coupling reaction with allylic halides, although a radical reaction and an intramolecular ligand coupling have been regarded as general under other conditions. Palladium catalysts were effective for the coupling reaction with allyl acetate. Copper iodide promoted the reaction of organic halides, such as methyl iodide and ethyl bromoacetate. In the latter two cases, the formation of diaryls is a significant side reaction.
- Fujiwara, Masahiro,Tanaka, Mutsuo,Baba, Akio,Ando, Hisanori,Souma, Yoshie
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- Electrophilic allylation of arenes with in situ generated allyltriarylbismuthonium compound: The Bismuth-mediated polarity inversion of allylsilanes
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Reaction of triarylbismuth difluorides 1 with allyltrimethylsilane 2 in CH2Cl2 in the presence of BF3·OEt2 at low temperature generates allyltriarylbismuthonium compound 3 as a pale yellow solution, in which aromatic hydrocarbons and ethers, triphenylphosphine, dimethyl sulfide, p-toluenesulfinate, and thiophenol are all readily allylated to afford the corresponding allyl derivatives in moderate to good yields.
- Matano, Yoshihiro,Yoshimune, Masanori,Suzuki, Hitomi
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p. 7475 - 7478
(2007/10/02)
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- Palladium Complexes Containing Rigid Bidentate Nitrogen Ligands as Catalysts for Carbon-Carbon Bond Formation
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Zerovalent Pd(Ar-BIAN)(dimethyl fumarate) and divalent PdCl2(Ar-BIAN) complexes containing the rigid bidentate nitrogen ligand bis(arylimino)acenaphthene (Ar-BIAN; Ar = C6H5, p-MeC6H4, p-MeOC6H4) are efficient catalysts for the cross coupling reaction of various organic halides (including acyl-, allyl-, aryl-, benzyl-, vinyl- and 1,2-dienylhalides) with organomagnesium, -zinc and -tin reagents.Coupling reactions of organic halides with one equivalent of organomagnesium and -zinc reagents, in the presence of 1 mol percent of a Pd(Ar-BIAN) catalyst, generally proceed smoothly in THF at 20 degC, giving complete conversion of the starting halide within 1-16 hours.Good isolated yields of carbon-carbon coupled products are obtained and the ratio cross/homo coupling varies between 98/2 and 0/100, depending on the substrates used.Reactions employing organotin reagents proceed best in DMF or HMPA and need longer reaction times and/or higher temperatures, as compared to organomagnesium and -zinc reagents, to go to completion.The selectivity for cross coupling is high (generally >99 percent) and high isolated yields of cross coupled products can be obtained.In the presence of carbon monoxide (1-5 bar) ketones can be formed with excellent selectivity and in good yields, as was demonstrated for the carbonylative coupling of benzyl bromide with tetramethyltin or (p-tolyl)trimethyltin.Comparison of some Pd(Ar-BIAN) catalyzed reactions with Pd-phosphine catalyzed reactions reveals that these reactions complement each other: for example, when a Pd(Ar-BIAN) catalyst was employed, the coupling of 2-methylallyl chloride with phenyltributyltin was much faster, whereas the coupling of iodobenzene with vinyltrimethyltin was much slower, as compared to the Pd(PPh3)n catalyzed reactions.
- Asselt, Rob van,Elsevier, Cornelis J.
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p. 323 - 334
(2007/10/02)
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- Functional Selectivity in Friedel-Crafts Alkylations with Polyfunctional Reactants over Acid Zeolites
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The selective formation of allyl-substituted aromatics over acid zeolites by electrophilic substitution of the aromatics with allyl alcohols is reported.In contrast to the reaction in homogeneous phase with H2SO4, this primary product is stable and almost no consecutive reactions of allyl-substitued aromatics are observed.When allyl chloride (7) is used as alkylating agent, nearly no allyl-substituted aromatic is obtained.HCl, liberated during reaction easily isomerizes the double bond, enabling a fast consecutive reaction.This implies that functional selectivity,which is unachievable in homogeneous phase can be easily reached over microporous solid Broensted acids, provided no homogeneous acid is formed during reaction.The functional selectivity is attributed to the suppression of bimolecular side reactions and to the reduced isomerization rate of the double bond.For the electrophilic aromatic substitution, the turnover number of the acid site is about 120, confirming the true catalytic nature of this reaction.Deactivation of the catalyst is attributed to the oligomerization of an olefin, made upon hydride transfer to an allyl cation.
- Espeel, P. H.,Janssens, B.,Jacobs, P. A.
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p. 7688 - 7693
(2007/10/02)
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- REACTION OF ALLYLTRIMETHYLSILANE WITH AN AROMATIC COMPOUND USING HYPERVALENT ORGANOIODINE COMPOUND: A NEW ALLYLATION OF AROMATIC COMPOUNDS
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New general method for the allylation of aromatic compounds from allyltrimethylsilane utilizing the combination of iodosylbenzene and BF3 OEt2 are described, which is based upon the umpolung of allyltrimethylsilane by way of cationic allylphenyliodonium (III) salt complex as an intermediate.
- Lee, Kilsung,Kim, Dae Young,Oh, Dong Young
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p. 667 - 668
(2007/10/02)
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- Structure of ω-Arylalkyl Radicals: A 13C CIDNP Investigation
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Thermolysis of a series of ω-arylalkanoyl m-chlorobenzoyl (and acetyl) peroxides at ca. 100 deg C in cyclohexanone and in hexachloroacetone was studied by using 13C chemically induced dynamic nuclear polarization.Analysis of the observed 13C polarizations indicate that all the three radicals (β-arylethyl, γ-arylpropyl and δ-arylbutyl) have open-chain structures with no evidence for aryl participation resulting in spirocycloalkylcyclohexadienyl radicals.
- Olah, George A.,Krishnamurthy, V. V.,Singh, Brij P.,Iyer, Pradeep S.
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p. 955 - 963
(2007/10/02)
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- Silicon-directed Elimination from β-Trimethylsilyl Sulphoxides and the Regiospecific Synthesis of Olefins
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The regiospecific formation of olefins by the thermal elimination of sulphenic acid from β-trimethylsilyl sulphoxides followed by protodesilylation is reported and the effect of the trimethylsilyl group on thermal elimination is discussed.
- Ochiai, Masahito,Tada, Shin-ichi,Sumi, Kenzo,Fujita, Eiichi
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p. 281 - 282
(2007/10/02)
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- A NEW SYNTHESIS OF 1,3-DIENES FROM ALLYL SULFIDES AND ALLYL SULFONES USING TRI-n-BUTYLSTANNYLMETHYL IODIDE
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Allyl 2-pyridyl sulfide 6 or allyl phenyl sulfone 7 on treatment with n-butyllithium in tetrahydrofuran followed by tri-n-butylstannylmethyl iodide (4) afforded directly the 1,3-diene 8 in good yield.
- Ochiai, Masahito,Tada, Shin-ichi,Sumi, Kenzo,Fujita, Eiichi
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p. 2205 - 2208
(2007/10/02)
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