- Free and immobilized lecitase ultra as the biocatalyst in the kinetic resolution of (E)‐4‐arylbut‐3‐en‐2‐yl esters
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The influence of buffer type, co‐solvent type, and acyl chain length was investigated for the enantioselective hydrolysis of racemic 4‐arylbut‐3‐en‐2‐yl esters using Lecitase Ultra (LU). Immobilized preparations of the Lecitase Ultra enzyme had
- Chojnacka, Anna,Drozd, Rados?aw,G?adkowski, Witold,Le?niarek, Aleksandra,Szymańska, Magdalena
-
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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
-
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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- Site-Selective α-Alkoxyl Alkynation of Alkyl Esters Mediated by Boryl Radicals
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A novel method for site-selective C-H functionalization of ethyl acetate mediated by pyridine-boryl radicals is presented, delivering a variety of 4-phenylbut-3-yn-2-yl acetate derivatives under mild conditions. A distinguishing feature of this reaction i
- Guo, Ao,Han, Jia-Bin,Zhu, Lei,Wei, Yin,Tang, Xiang-Ying
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supporting information
p. 2927 - 2931
(2019/04/17)
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- Copper-Catalyzed Highly Stereoselective Trifluoromethylation and Difluoroalkylation of Secondary Propargyl Sulfonates
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It is challenging to stereoselectively introduce a trifluoromethyl group (CF3) into organic molecules. To date, only limited strategies involving direct asymmetric trifluoromethylation have been reported. Herein, we describe a new strategy for direct asymmetric trifluoromethylation through the copper-catalyzed stereospecific trifluoromethylation of optically active secondary propargyl sulfonates. The reaction enables propargylic trifluoromethylation with high regioselectivity and stereoselectivity. The reaction could also be extended to stereospecific propargylic difluoroalkylation. Transformations of the resulting enantiomerically enriched fluoroalkylated alkynes led to a variety of chiral fluoroalkylated compounds, thus providing a useful protocol for applications in the synthesis of fluorinated complexes.
- Gao, Xing,Xiao, Yu-Lan,Wan, Xiaolong,Zhang, Xingang
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supporting information
p. 3187 - 3191
(2018/02/26)
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- Enantioselective NiH/Pmrox-Catalyzed 1,2-Reduction of α,β-Unsaturated Ketones
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The enantioselective 1,2-reduction of α,β-unsaturated ketones was achieved using a NiH catalyst in the presence of pinacolborane. This mild process represents a general method to access a wide variety of structurally diverse α-chiral allylic alcohols in excellent yields and enantioselectivity, as well as very high levels of ambidoselectivity for 1,2- over 1,4-reduction. Furthermore, for reactions on a 10 mmol scale, catalyst loadings as low as 0.5 mol % could be employed to deliver product without any detrimental effect on the yield, enantio-, or ambidoselectivity.
- Chen, Fenglin,Zhang, Yao,Yu, Lei,Zhu, Shaolin
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p. 2022 - 2025
(2017/02/15)
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- Synthesis of Chiral α,β-Unsaturated γ-Amino Esters via Pd-Catalyzed Asymmetric Allylic Amination
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A Pd-catalyzed asymmetric allylic amination of 4-substituted 2-acetoxybut-3-enoates with amines has been developed for the regiospecific synthesis of chiral α,β-unsaturated γ-amino esters. The desired chiral aminated products can be obtained in up to 98%
- Xia, Chao,Shen, Jiefeng,Liu, Delong,Zhang, Wanbin
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p. 4251 - 4254
(2017/08/23)
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- Facile synthesis of Z -alkenes via uphill catalysis
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Catalytic access to thermodynamically less stable Z-alkenes has recently received considerable attention. These approaches have relied upon kinetic control of the reaction to arrive at the thermodynamically less stable geometrical isomer. Herein, we present an orthogonal approach which proceeds via photochemically catalyzed isomerization of the thermodynamic E-alkene to the less stable Z-isomer which occurs via a photochemical pumping mechanism. We consider two potential mechanisms. Importantly, the reaction conditions are mild, tolerant, and operationally simple and will be easily implemented.
- Singh, Kamaljeet,Staig, Shannon J.,Weaver, Jimmie D.
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p. 5275 - 5278
(2014/05/06)
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- Highly enantioselective synthesis of 3-substituted furanones by palladium-catalyzed kinetic resolution of unsymmetrical allyl acetates
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Resolving the issue: A near-perfect Pd-catalyzed kinetic resolution of 1,3-disubstituted unsymmetrical allylic acetates uses silyl enol ethers as nucleophiles to access the important 3-substituted-furanone scaffold (see scheme; DACH=diaminocyclohexyl, dba=dibenzylideneacetone). The reaction proceeds under mild conditions and provides the desired products with excellent chemo-, regio-, and enantioselectivity. Copyright
- Mao, Bin,Ji, Yining,Fananas-Mastral, Martin,Caroli, Giuseppe,Meetsma, Auke,Feringa, Ben L.
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p. 3168 - 3173
(2012/05/05)
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- A simple and efficient method for the allylation of heteroarenes catalyzed by PdCl2
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The PdCl2-catalyzed allylation of heteroarenes is presented. Various heteroarenes including O-, N-, and S-based ones were allylated efficiently with a rich range of allylic acetates in the presence of only 2 mol % of PdCl2, without the need of bases/acids, additives, and external supporting ligands. In addition, the reactions were carried out under mild and simple conditions just by stirring the two reactants and catalyst in CH 2Cl2 at 60 °C. Moreover, the by-product produced was non-toxic acetic acid. Thus, the method presented in this work provides a general, clean, and operationally simple approach for the functionalization of heteroarenes. Finally, a preliminary mechanistic study suggested that the Pd(II) may be reduced in situ by the heteroarenes to Pd(0), which serves as the active metal center to catalyze the following allylations of heteroarenes via a Tsuji-Trost pathway.
- Yuan, Feng-Quan,Sun, Feng-Yi,Han, Fu-She
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p. 6837 - 6842
(2012/08/28)
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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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- 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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- 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
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supporting information; experimental part
p. 2980 - 2983
(2009/12/05)
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- Enzymatic resolution of chlorohydrins for the synthesis of enantiomerically enriched 2-vinyloxiranes
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A series of vinylchlorohydrins are resolved by enzymatic kinetic resolution. The resulting R-alcohols, obtained in up to 99% ee, are stereoselectively converted into vinyloxiranes in high yield. The S-acetates, obtained in up to 99% ee were either deprotected to S-alcohols, or cyclized directly to vinyl oxiranes under basic conditions, with moderate to no loss in ee. The results are consistent with a racemization mechanism involving reversible migration of the acetate during deprotection. Georg Thieme Verlag Stuttgart.
- McCubbin, J. Adam,Maddess, Matthew L.,Lautens, Mark
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p. 289 - 293
(2008/12/21)
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- A novel palladium-catalyzed hydroalkoxylation of alkenes with a migration of double bond
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A novel palladium-catalyzed addition of alcohols to olefins was developed, in which a migration of double bond was involved. By this new method, a variety of allylic ethers were prepared with moderate to high yields under mild conditions. The Royal Society of Chemistry.
- Tan, Jiajing,Zhang, Zuhui,Wang, Zhiyong
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experimental part
p. 1344 - 1348
(2008/10/09)
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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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- An efficient one-pot synthesis of unsymmetrical ethers: A directly reductive deoxygenation of esters using an InBr3/Et3SiH catalytic system
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(Chemical Equation Presented) This study describes a novel one-pot procedure for a directly reductive conversion of the carbonyl function of esters to the corresponding ethers by Et3SiH in the presence of a catalytic amount of InBr3.
- Sakai, Norio,Moriya, Toshimitsu,Konakahara, Takeo
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p. 5920 - 5922
(2008/02/09)
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- Asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens
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A new asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens has been found. Although alcohols are not the natural substrates for this enzyme, a high R enantioselectivity was observed. Stereochemical studies showed that variations in substrate structure lead to strong variations in enantioselectivity. The highest enantioselectivities are obtained when the β-carbon of the secondary alcohol is tertiary or quaternary.
- Hatzakis, Nikos S.,Smonou, Ioulia
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p. 325 - 337
(2007/10/03)
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- Palladium-catalyzed asymmetric synthesis of allylic alcohols from unsymmetrical and symmetrical racemic allylic carbonates featuring C-O-bond formation and dynamic kinetic resolution
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Described is the asymmetric synthesis of the allylic alcohols 11 (85% ee), 15 (99% ee), 17 (93% ee), 19 (61% ee), and 21 (69% ee) through a Pd-catalyzed reaction of the unsymmetrical carbonates rac-10, rac-12, rac-14, rac-16, rac-18, and rac-20, respectively, with KHCO3 and H2O in the presence of bisphosphane 6. Similarly the allylic alcohols 23 (99% ee) and 25 (97% ee) have been obtained from the symmetrical carbonates rac-22 and rac-24, respectively. Reaction of the meso-biscarbonate 26 with H2O and Pd(0)/6 afforded alcohol 27 (96% ee), which was converted to the PG building block 32. The unsaturated bisphosphane 33 showed in the synthesis of alcohols 36, 37, and 39 a similar high selectivity as 6. The formation of alcohols 11, 15, and 17 involves an efficient dynamic kinetic resolution.
- Gais, Hans-Joachim,Bondarev, Oleg,Hetzer, Ralf
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p. 6279 - 6283
(2007/10/03)
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- Radical reactions in esters with alkoxy functionality chemistry an unusual alcohol moiety hydrogen abstraction
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Various geometrically pure (E)-alkenes have been synthesized by radical substitution of alcohol moieties generated via hydrogen abstraction within ethyl esters. These reactions occurred with high regioselectivity and gave a new access to 1-methyl-3-aryl-allyl esters.
- Yan, Ming-Chung,Jang, Yeong-Jiunn,Wu, Jhenyi,Lin, Yung-Feng,Yao, Ching-Fa
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p. 3685 - 3687
(2007/10/03)
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- Using a lipase as a high-throughput screening method for measuring the enantiomeric excess of allylic acetates
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This report describes a high-throughput method for measuring the enantiomeric excess of allylic acetates. Such methods are useful tools for screening libraries of potential catalysts for enantioselective reactions. This technique, which is called EMDee fo
- Onaran, M. Burak,Seto, Christopher T.
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p. 8136 - 8141
(2007/10/03)
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- Asymmetric hydrogenation of an α,β-unsaturated ketone by diamine(ether-phosphine)ruthenium(II) complexes and lipase-catalyzed kinetic resolution: A consecutive approach
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The RuCl2(η1-Ph2PCH2CH 2OCH3)2(diamine) complexes 2L1-2L5 have been prepared in high yields from the reaction of equimolar amounts of RuCl2(η2-Ph2PCH2CH 2OCH3)2 1 with various kinds of chelating diamines L1-L5 to form five-membered chelates with ruthenium. These novel ruthenium(II) complexes have been used as catalysts in the asymmetric hydrogenation of the prochiral ketone trans-4-phenyl-3-butene-2-one 3, using 2-propanol and different types of cocatalysts. Whereas complexes with achiral diamines afforded the racemic alcohols, complexes with chiral diamines (R,R or S,S) allowed the formation of the corresponding enantiomerically enriched secondary alcohol (S or R) with ee values of 45%. In order to obtain the secondary alcohol with ee of >99%, the kinetic resolution of enantiomerically enriched trans-4-phenyl-3-butene-2-ol 3 was performed in a consecutive approach using either the lipase-catalyzed enantioselective transesterification of the alcohol with isopropenyl acetate as the acyl donor in toluene or the enantioselective hydrolysis of the corresponding acetate in buffer. The determination of the enantiomeric excess (ee) of the resulting enantiomerically enriched secondary alcohols was performed by gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as the chiral stationary phase.
- Lindner, Ekkehard,Ghanem, Ashraf,Warad, Ismail,Eichele, Klaus,Mayer, Hermann A.,Schurig, Volker
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p. 1045 - 1053
(2007/10/03)
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- Lipase-catalyzed access to enantiomerically pure (R)- and (S)-trans-4-phenyl-3-butene-2-ol
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The enzymatic kinetic resolution of (RS)-trans-4-phenyl-3-butene-2-ol was investigated by screening a range of lipases both for enantioselective transesterification and for enantioselective hydrolysis of its acetate. The lipase from Pseudomonas cepacia immobilized on diatomaceous earth (PSL-D)-catalyzed asymmetric transesterification was performed on gram scale using isopropenyl acetate as an innocuous acyl donor in organic media affording the (S)-alcohol in high enantiomeric excess (>99% ee) and enantiomeric ratio E >150. The lipase (Candida antarctica B, CAL-B)-catalyzed asymmetric hydrolysis of the racemic acetate was performed on gram scale in phosphate buffer affording the (R)-alcohol in high enantiomeric excess (>99% ee) and enantiomeric ratio E >150. The investigation demonstrates that the transesterification of the racemic alcohol in organic solvent was faster than the hydrolysis of the corresponding acetate in phosphate buffer. A GC method was developed to achieve an effective analytical separation of the enantiomers of both substrate and product in one analysis using the chiral stationary phase heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin.
- Ghanem, Ashraf,Schurig, Volker
-
-
- Molybdenum(0) and tungsten(0) catalysts with enhanced reactivity for allylic substitution: Regioselectivity and solvent effects
-
The binuclear Mo(II) and W(II) complexes 28a,b and 29a,b have been developed as pre-catalysts for allylic substitution with β-dicarbonyl nucleophiles. These complexes are reduced in situ to Mo(0) and W(0) catalytic species 30a,b and 31a,b by excess of NaH, employed to generate sodiomalonate nucleophiles, or by DIBAL-H. 1,3-Dioxolane and 1,4-dioxane, when used as solvents, substantially accelerate the reaction. These new catalysts exhibit "traditional" Mo regiochemistry, i.e., the nucleophilic attack occurring preferentially at the more substituted carbon (5 → 9; 37 → 38), unless an additional factor, such as further coordination to another moiety of the allylic electrophile takes part (41), as in the case of the geranyl-type substrates (32 or 33 → 36).
- Malkov,Baxendale,Mansfield,Kocovsky
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p. 1234 - 1240
(2007/10/03)
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- The kinetic resolution of allylic alcohols by a non-enzymatic acylation catalyst; application to natural product synthesis
-
A planar-chiral DMAP derivative is shown to serve as an effective catalyst for the kinetic resolution of allylic alcohols; to illustrate its practical utility, the catalyst is applied to the resolution of two alcohols that have been employed as intermedia
- Bellemin-Laponnaz, Stephane,Tweddell, Jennifer,Ruble, J. Craig,Breitling, Frank M.,Fu, Gregory C.
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p. 1009 - 1010
(2007/10/03)
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- Highly chemoselective catalytic hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols using phosphine-stabilized copper(I) hydride complexes
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A base metal hydrogenation catalyst composed of the phenyldimethylphosphine-stabilized copper(I) hydride complex provides for the highly chemoselective hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols, including the regioselective 1,2-reduction of α,β- unsaturated ketones and aldehydes to allylic alcohols. The active catalyst can be derived in situ by phosphine exchange using commercial [(Ph3P)CuH]6 or from the reaction of copper(l) chloride, sodium tert-butoxide, and dimethylphenylphosphine under hydrogen. The catalyst derived from 1,1,1- tris(diphenylphosphinomethyl)ethane is mechanistically interesting but less synthetically useful. (C) 2000 Elsevier Science Ltd.
- Chen, Jian-Xin,Daeuble, John F.,Brestensky, Donna M.,Stryker, Jeffrey M.
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p. 2153 - 2166
(2007/10/03)
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- Palladium(II)-catalyzed phenylation of unsaturated compounds using phenylantimony chlorides under air
-
Diphenylantimony chloride and phenylantimony dichloride, mainly the former, react smoothly with alkenes in acetonitrile at r.t. in the presence of a catalytic amount of Pd(OAc)2 under air to afford the corresponding phenylated alkenes (Heck-type reaction). The addition of AgOAc as reoxidant is not necessary for this reaction in sharp contrast to similar reactions using triarylstibines. The oxygen absorption is confirmed in this catalytic reaction and the reaction does not proceed catalytically in palladium(II) under inert gases, such as nitrogen or argon. Even under air the addition of a radical scavenger stopped the reaction. The regeneration of PhPdOAc species from Ph2SbCl, HPdOAc species and oxygen is proposed as a key step in the catalytic cycle where oxygen-containing radical species might be present as intermediates.
- Matoba, Kazutaka,Motofusa, Shin-Ichi,Sik Cho, Chan,Ohe, Kouichi,Uemura, Sakae
-
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- Cobalt(II)-Catalyzed Conversion of Allylic Alcohols/Acetates to Allylic Amides in the Presence of Nitriles
-
Various secondary allylic alcohols or their acetates and tertiary allylic alcohols can be converted to the corresponding transposed allylic amides in the presence of a catalytic quantity of cobalt(II) chloride and acetic anhydride in acetonitrile.Tertiary alcohols undergo complete rearrangement whereas secondary ones afford a mixture of regioisomers.Moderate yields of amides are also obtained by reacting acrylonitrile with secondary alcohols in 1,2-dichloroethane.The presence of acetic anhydride or acetic acid is crucial to the formation of amides as the absence of the former affords no amides and the allylic alcohols are mainly recovered as regioisomeric mixtures.The regioselectivity during amide formation can be enhanced by using cobalt complexes 14-16 in acetic acid medium.Some preliminary studies indicate that these reactions are proceeding via an ?-allyl complex or tight ion pair rather than a sigmatropic rearrangement of acetamidate obtained in a Pinner reaction.
- Mukhopadhyay, Manoj,Reddy, M. Madhava,Maikap, G. C.,Iqbal, Javed
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p. 2670 - 2676
(2007/10/02)
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- Catalytic and Efficient Cleavage of Allylic and Tertiary Benzylic Ethers and Esters with Ce(IV)
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The reaction of cerium(IV) as ceric ammonium nitrate (CAN) with a variety of allylic and tertiary benzylic ethers and esters has been examined in different alcohols and acetic acid under catalytic and mild conditions.Experiments have been conducted to elu
- Iranpoor, Nasser,Mottaghinejad, Enayatolah
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p. 7299 - 7306
(2007/10/02)
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- A Regioselective and Stereospecific Synthesis of Allylsilanes from Secondary Allylic Alcohol Derivatives
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Primary and secondary allylic acetates and benzoates react with the dimethyl(phenyl)silyl-cuprate reagent to give allylsilanes, provided that the THF in which the cuprate is prepared is diluted with ether before addition of the allylic ester.The reaction is reasonably regioselective in some cases: (i) when the allylic system is more-substituted at one end than the other, as in the reactions 4->5 and 9->10; (ii) when the steric hindrance at one end is neopentyl-like, as in the reactions 15->16; and (iii) when the disubstituted double bond has the Z configuration, as in th e reactions Z-19->E-21 or, better, because the silyl group is becoming attached to the less-sterically hindered end of the allylic system, Z-20->E-22.The regioselectivity is better if a phenyl carbamate is used in place of the ester, and a three-step protocol assembling the mixed cuprate on the leaving group is used, as in the reactions 23->24 and E- or Z-29->E-21, or, best of all, because the silyl group is again becoming attached to the less-sterically hindered end of the allylic system, E- or Z-30->E-22.This sequence works well to move the silyl group onto the more substituted end of an allyl system, but only when the move is from a secondary allylic carbamate to a tertiary allylsilane, as in the reaction 38->39.Allyl(trimethyl)silanes can be made using alkyl- or aryl-cuprates on trimethylsilyl-containing allylic esters and carbamates, as in the reactions 40->41, and 43->44.The reaction of the silyl-cuprate with allylic esters and the three-step sequence with the allylic carbamates are stereochemically complementary, the former being stereospecifically anti and the latter stereospecifically syn.Homochiral allylsilanes can be ma de by these methods with high levels of stereospecificity, as shown by the synthesis of the allylsilanes 54, 58 and 59.
- Fleming, Ian,Higgins, Dick,Lawrence, Nicholas J.,Thomas, Andrew P.
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p. 3331 - 3350
(2007/10/02)
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- Homogeneous Catalysis. Transition-Metal-Catalyzed Claisen Rearrangements
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Palladium(0), palladium(II), rhodium(I), and iridium(I) complexes catalyze the rearrangement of allyl imidates to allyl amides under mild conditions.The palladium(II) catalysis is characterized by exclusive regioselectivity and high steroeselectivity whereas the palladium(0), rhodium(I), and iridium(I) catalysts generally give both the and rearrangement products and although the palladium(0) catalyst can give high stereoselectivity, the rhodium(I) and iridium(I) catalysts are nonstereoselective.After a series of experiments using chiral substrates and substrates with specific deuterium labels, the mechanisms of these catalytic reactions have been elucidated.The palladium(II) catalysis is proposed to proceed via cyclic carbonium ion intermediates, and the mechanism resembles the thermal uncatalyzed Claisen rearrangement path.The palladium(0) catalysis is a form of catalytic allylation involving oxidative addition followed by nucleophilic attack on a ?-allyl intermediate.The mechansim of the rhodium(I) and iridium(I) catalysis was not as fully investigated as the others, but it appears to involve carbonium ion intermediates formed by cleavage of the allyl-oxygen bond.
- Schenck, Terry G.,Bosnich, B.
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p. 2058 - 2066
(2007/10/02)
-
- Oxidation by Cobalt(III) Acetate. Part 8. Effects of Substituents on Product Distributions in Oxidation of Aromatic Olefins by Cobalt(III) Acetate
-
Oxidation of aromatic olefins by cobalt(III) acetate in acetic acid under nitrogen gave both allylic acetates and glycol monoacetates.Disubstituted olefins were oxidized by the oxidant to give predominantly allylic acetates.Glycol monoacetates were minor products except for the case of 1-phenylisobutene which was slowly oxidized to give the corresponding glycol monoacetate.In the oxidation of tri- and tetra-substituted olefins, the yield of glycol monoacetate increased at the expense of that of allylic acetate.A mechanism, in which the reaction proceeds through a Co-co-ordinated radical kation formed by an one-electron abstraction from olefin by cobalt(III) acetate, is suggested.
- Morimoto, Takashi,Hirano, Masao,Koyama, Tsuyoshi
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p. 1109 - 1116
(2007/10/02)
-