- Catalytic asymmetric bromocyclization of polyenes
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The first catalytic asymmetric bromonium ion-induced polyene cyclization has been achieved by using a chiral BINOL-derived thiophosphoramide catalyst and 1,3-dibromo-5,5-dimethylhydantoin as an electrophilic bromine source. Bromocyclization products are o
- Samanta, Ramesh C.,Yamamoto, Hisashi
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supporting information
p. 1460 - 1463
(2017/02/10)
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- A palladium NNC-pincer complex: An efficient catalyst for allylic arylation at parts per billion levels
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Allylic arylation of allylic acetates by sodium tetraarylborates in the presence of ppb to ppm (molar) loadings of a palladium NNC-pincer complex catalyst in methanol at 50°C gave the corresponding arylated products in excellent yields. Total turnover numbers of up to 500 000 000 and turnover frequencies of up to 11 250 000 h-1 were achieved.
- Hamasaka, Go,Sakurai, Fumie,Uozumi, Yasuhiro
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supporting information
p. 3886 - 3888
(2015/03/04)
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- COMPOUNDS CAPABLE OF RELEASING FRAGRANT COMPOUNDS
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Provided is class of compounds of formula (I) wherein X, R1, R2 and R3 have the same meaning as given in the specification capable of releasing fragrant compounds in a controlled manner into the surroundings.
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Page/Page column 17
(2012/07/13)
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- Self-assembled poly(imidazole-palladium): Highly active, reusable catalyst at parts per million to parts per billion levels
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Metalloenzymes are essential proteins with vital activity that promote high-efficiency enzymatic reactions. To ensure catalytic activity, stability, and reusability for safe, nontoxic, sustainable chemistry, and green organic synthesis, it is important to develop metalloenzyme-inspired polymer-supported metal catalysts. Here, we present a highly active, reusable, self-assembled catalyst of poly(imidazole-acrylamide) and palladium species inspired by metalloenzymes and apply our convolution methodology to the preparation of polymeric metal catalysts. Thus, a metalloenzyme-inspired polymeric imidazole Pd catalyst (MEPI-Pd) was readily prepared by the coordinative convolution of (NH4)2PdCl4 and poly[(N-vinylimidazole)-co-(N- isopropylacrylamide)5] in a methanol-water solution at 80 °C for 30 min. SEM observation revealed that MEPI-Pd has a globular-aggregated, self-assembled structure. TEM observation and XPS and EDX analyses indicated that PdCl2 and Pd(0) nanoparticles were uniformly dispersed in MEPI-Pd. MEPI-Pd was utilized for the allylic arylation/alkenylation/vinylation of allylic esters and carbonates with aryl/alkenylboronic acids, vinylboronic acid esters, and tetraaryl borates. Even 0.8-40 mol ppm Pd of MEPI-Pd efficiently promoted allylic arylation/alkenylation/vinylation in alcohol and/or water with a catalytic turnover number (TON) of 20 000-1 250 000. Furthermore, MEPI-Pd efficiently promoted the Suzuki-Miyaura reaction of a variety of inactivated aryl chlorides as well as aryl bromides and iodides in water with a TON of up to 3 570 000. MEPI-Pd was reused for the allylic arylation and Suzuki-Miyaura reaction of an aryl chloride without loss of catalytic activity.
- Yamada, Yoichi M. A.,Sarkar, Shaheen M.,Uozumi, Yasuhiro
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supporting information; experimental part
p. 3190 - 3198
(2012/04/10)
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- Selective cross-coupling of organic halides with allylic acetates
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A general protocol for the coupling of haloarenes with a variety of allylic acetates is presented. Strengths of the method are a tolerance for electrophilic (ketone, aldehyde) and acidic (sulfonamide, trifluoroacetamide) substrates and the ability to couple with a variety of substituted allylic acetates. Secondary alkyl bromides can also be allylated under slightly modified conditions, demonstrating the generality of the approach. Finally, the coupling of a reactive vinyl halide could be achieved by the use of a very hindered ligand and more reactive, branched allylic acetates.
- Anka-Lufford, Lukiana L.,Prinsell, Michael R.,Weix, Daniel J.
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supporting information
p. 9989 - 10000
(2013/01/15)
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- Palladium-catalyzed cross-coupling reactions of organogold(i) phosphanes with allylic electrophiles
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Aryl and alkenylgold(i) phosphanes react regioselectively with allylic electrophiles such as cinnamyl and geranyl halides (bromide, chloride and acetates) under palladium catalysis in THF at 80 °C to afford the α-substitution product with moderate to high yields. When the reaction is performed with a chiral enantiopure secondary acetate, the α-substituted cross-coupling product is obtained with complete inversion of the stereochemistry.
- Pena-Lopez, Miguel,Ayan-Varela, Miguel,Sarandeses, Luis A.,Sestelo, Jose Perez
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experimental part
p. 1686 - 1694
(2012/03/22)
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- A highly active and reusable self-assembled poly(imidazole/palladium) catalyst: Allylic arylation/alkenylation
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Gobs of globules: A polymeric imidazole/acrylamide palladium catalyst, MPPI-Pd (M=PdIICl and Pd0), was utilized for the allylic arylation/alkenylation of allylic esters with aryl/alkenylboronic acids and tetraaryl borates. Low catalyst loadings efficiently promoted the reaction with a catalytic turnover number of 20000-1250000. The catalyst can be reused without loss of catalytic activity.
- Sarkar, Shaheen M.,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
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supporting information; experimental part
p. 9437 - 9441
(2011/11/06)
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- Cu(I)-catalyzed, α-selective, allylic alkylation reactions between phosphorothioate esters and organomagnesium reagents
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Regiocontrol of allylic alkylation reactions involving hard nucleophiles remains a significant challenge and continues to be an active area of research. The lack of general methods in which α-alkylation is favored underscores the need for the development of new processes for achieving this type of selectivity. We report that Cu(I) catalyzes the allylic substitution of phosphorothioate esters with excellent α-regioselectivity, regardless of the nature of the Grignard reagent that is used. To the best of our knowledge, the Cu-catalyzed allylic alkylation of phosphorothioate esters has never been described. We have also developed a simple protocol for inducing high α selectivity starting from secondary allylic halides. This is accomplished by using sodium phosphorothioates as an additive.
- Lauer, Andrew M.,Mahmud, Farzeen,Wu, Jimmy
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supporting information; experimental part
p. 9119 - 9123
(2011/08/04)
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- Palladium-catalyzed cross-couplings of allylic phosphates
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A range of palladium-catalyzed cross-coupling reactions can be performed using allylic phosphates as electrophiles. Both conventional heating and microwave irradiation can be used.
- Maslak, Veselin,Tokic-Vujosevic, Zorana,Saicic, Radomir N.
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supporting information; experimental part
p. 1858 - 1860
(2009/07/19)
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- Preparation, structure, and reactivity of nonstabilized organoiron compounds. Implications for iron-catalyzed cross coupling reactions
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A series of unprecedented organoiron complexes of the formal oxidation states -2, 0, +1, +2, and +3 is presented, which are largely devoid of stabilizing ligands and, in part, also electronically unsaturated (14-, 16-, 17- and 18-electron counts). Specifically, it is shown that nucleophiles unable to undergo β-hydride elimination, such as MeLi, PhLi, or PhMgBr, rapidly reduce Fe(3+) to Fe(2+) and then exhaustively alkylate the metal center. The resulting homoleptic organoferrate complexes [(Me4Fe)(MeLi)] [Li(OEt2)]2 (3) and [Ph4Fe][Li(Et 2O)2][Li(1,4-dioxane)] (5) could be characterized by X-ray crystal structure analysis. However, these exceptionally sensitive compounds turned out to be only moderately nucleophilic, transferring their organic ligands to activated electrophiles only, while being unable to alkylate (hetero)aryl halides unless they are very electron deficient. In striking contrast, Grignard reagents bearing alkyl residues amenable to β-hydride elimination reduce FeXn (n = 2, 3) to clusters of the formal composition [Fe(MgX)2]n. The behavior of these intermetallic species can be emulated by structurally well-defined lithium ferrate complexes of the type [Fe(C2H4) 4][Li(tmeda)]2 (8), [Fe(cod)2][Li(dme)] 2 (9), [CpFe(C2H4)2][Li(tmeda)] (7), [CpFe(cod)][Li(dme)] (11), or [Cp*Fe(C2H4) 2][Li(tmeda)] (14). Such electron-rich complexes, which are distinguished by short intermetallic Fe-Li bonds, were shown to react with aryl chlorides and allyl halides; the structures and reactivity patterns of the resulting organoiron compounds provide first insights into the elementary steps of low valent iron-catalyzed cross coupling reactions of aryl, alkyl, allyl, benzyl, and propargyl halides with organomagnesium reagents. However, the acquired data suggest that such C-C bond formations can occur, a priori, along different catalytic cycles shuttling between metal centers of the formal oxidation states Fe(+1)/Fe(+3), Fe(0)/Fe(+2), and Fe(-2)/Fe(0). Since these different manifolds are likely interconnected, an unambiguous decision as to which redox cycle dominates in solution remains difficult, even though iron complexes of the lowest accessible formal oxidation states promote the reactions most effectively.
- Fuerstner, Alois,Martin, Ruben,Krause, Helga,Seidel, Guenter,Goddard, Richard,Lehmann, Christian W.
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p. 8773 - 8787
(2008/12/23)
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- Highly stereoselective cobalt-catalyzed allylation of functionalized diarylzinc reagents
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Functionalized diarylzinc reagents react readily with allylic chlorides or phosphates in the presence of Co(acac)2 (10 mol%) to give the S N2 products in high yields and with retention of the double-bond configuration. Functionalities like ester, ketone, or cyano are tolerated. Georg Thieme Verlag Stuttgart.
- Dunet, Guillaume,Knochel, Paul
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p. 1383 - 1386
(2008/02/13)
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- Oxidative addition of N-halosuccinimides to palladium(0): The discovery of neutral palladium(II) imidate complexes, which enhance Stille coupling of allylic and benzylic halides
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The Stille coupling of organostannanes and organohalides, mediated by air and moisture stable palladium(II) phosphine complexes containing succinimide or phthalimide (imidate) ligands, has been investigated. An efficient synthetic route to several palladium(II) complexes containing succinimide and phthalimide ligands, has been developed. cis-Bromobis(triphenylphosphine)(N-succinimide) palladium(II) [(Ph3P)2Pd(N-Succ)Br] is shown to mediate the Stille coupling of allylic and benzylic halides with alkenyl, aryl and allyl stannanes. In competition experiments between 4-nitrobromobenzene and benzyl bromide with a cis-stannylvinyl ester, (Ph3P)2Pd(N-Succ)Br preferentially cross-couples benzyl bromide, whereas with other commonly employed precatalysts 4-nitrobromobenzene undergoes preferential cross-coupling. Furthermore, preferential reaction of deactivated benzyl bromides over activated benzyl bromides is observed for the first time. The type of halide and presence of a succinimide ligand are essential for effective Stille coupling. The type of phosphine ligand is also shown to alter the catalytic activity of palladium(II) succinimide complexes.
- Crawforth, Catherine M.,Burling, Suzanne,Fairlamb, Ian J. S.,Kapdi, Anant R.,Taylor, Richard J. K.,Whitwood, Adrian C.
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p. 9736 - 9751
(2007/10/03)
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- Cross-coupling of alkyl halides with aryl Grignard reagents catalyzed by a low-valent iron complex
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A striking reversal of the usual reactivity pattern of aryl Grignard reagents is observed for reactions in the presence of catalytic amounts of the "bare" ferrate complex [Li(tmeda)]2[Fe(C2H 4)4] (1). Highly reduced iron-magnesium clusters may play a decisive role in the exceptionally facile and chemoselective cross-coupling reaction with alkyl halides (see scheme).
- Martin, Ruben,Fuerstner, Alois
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p. 3955 - 3957
(2007/10/03)
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- Efficient and selective Stille cross-coupling of benzylic and allylic bromides using bromobis(triphenylphosphine)(N-succinimide)palladium(II)
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Allylic and benzylic bromides are cross-coupled with organostannanes efficiently using the precatalyst [Pd(NCOC2H4CO)(PPh 3)2Br] 1. Significantly, these reactions do not require the use of hexamethylphosphoramide (HMPA) as the solvent, or additional ligands, such as trifurylphosphine or triphenylarsine. Selectivity for benzyl bromide over bromobenzene is observed for precatalyst 1, against the precatalysts, bromobis(triphenylphosphine)(benzyl)palladium(II) and bis(triphenylphosphine) palladium(II) bromide.
- Crawforth, Catherine M.,Fairlamb, Ian J. S.,Taylor, Richard J. K.
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p. 461 - 465
(2007/10/03)
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- Palladium-catalyzed cross-coupling reactions of allylic halides and acetates with indium organometallics
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The palladium(0)-catalyzed cross-coupling reaction of allylic halides and acetates with indium organometallics is reported. In this synthetic transformation, triorganoindium compounds and tetraorganoindates (aryl, alkenyl, and methyl) react with cinnamyl
- Rodriguez, David,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 8136 - 8139
(2007/10/03)
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- Copper-catalyzed regioselective allylic substitution reactions with indium organometallics
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The first nucleophilic allylic substitution reactions of triorganoindium compounds with allylic halides and phosphates are reported. The reactions of trialkyl- and triarylindium reagents with cinnamyl and geranyl halides and phosphates, with the aid of co
- Rodriguez, David,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 2518 - 2520
(2007/10/03)
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- Synthesis of Farnesol Analogues through Cu(I)-Mediated Displacements of Allylic THP Ethers by Grignard Reagents
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The synthesis of a family of farnesol analogues, incorporating aromatic rings, has been achieved in high yields through the development of a regioselective coupling of allylic tetrahydropyranyl ethers with organometallic reagents. The allylic THP group is displaced readily by Grignard reagents in the presence of Cu(I) halides but is stable in the absence of added copper. Thus, an allylic THP group can fulfill its traditional role as a protecting group or serve as a leaving group depending on reaction conditions. An improved synthesis of (2E,6E)-10,11-dihydrofarnesol also has been accomplished using this methodology, and some preliminary studies on the reactivity and regioselectivity of THP ether displacements were conducted. The farnesol analogues reported herein may be useful probes of the importance of nonbonding interactions in enzymatic recognition of the farnesyl chain and allow development of more potent competitive inhibitors of enzymes such as farnesyl protein transferase.
- Mechelke, Mark F.,Wiemer, David F.
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p. 4821 - 4829
(2007/10/03)
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- Palladium-catalyzed cross-coupling reaction of allyl carbonates with organostannanes
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Allyl carbonates are excellent substrates for the palladium(0)-catalyzed coupling reaction with stannanes under very mild conditions. The reaction proceeds via (η3-allyl)palladium complexes which undergo syn-anti equilibration with a rate simil
- Castano, Ana M.,Echavarren, Antonio M.
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p. 6587 - 6590
(2007/10/03)
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- Regiocontrol in Copper-Catalyzed Cross Coupling of Allylic Chlorides with Aryl Grignard Reagents
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The regioselectivity of copper-catalyzed reactions of allylic chlorides with aryl Grignard reagents was studied by variation of addition time of Grignard reagent, temperature, and amount of catalyst.It was found that slow addition of the Grignard reagent, increased temperature, and increased amount of catalyst favors formation of γ-product.Investigation of preformed organocopper species "Ar2CuMgBr" and "ArCu(X)MgBr" showed a striking difference in regioselectivity between the two reagents, the latter giving about 90percent γ-selectivity and the former being nonregioselective.It was found that for "ArCu(X)MgBr" the γ-selectivity increased with the electronegativity of the halide X (I Br Cl).
- Baeckvall, Jan-E.,Persson, Eva S. M.,Bombrun, Agnes
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p. 4126 - 4130
(2007/10/02)
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- Palladium-Catalyzed Coupling of Allylic Acetates with Aryl- and Vinylstannanes
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The palladium-catalyzed reaction of allyl acetates with aryl- and vinyltin reagents gave good yields of cross-coupled products.The reaction was mild and tolerant of functionality (CO2R, OH, OSiR3, OMe) in the tin reagent.Inversion of stereochemistry at the acetate center was observed, with retention of the geometry of the olefin of the allyl group and with exclusive coupling at the primary position.Retention of geometry of the olefin in the vinyltin reagents was also observed.
- Valle, L. Del,Stille, J. K.,Hegedus, L. S.
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p. 3019 - 3023
(2007/10/02)
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- PALLADIUM-CATALYZED PHENYLATION OF ALLYLIC ACETATES BY TETRAPHENYLBORATE ANION
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Commercial sodium tetraphenylborate is a convenient phenylating reagent in the palladium(0)-catalyzed substitution of allylic acetates.Two phenyl groups of NaBPh4 are available for transfer.Triphenylboron is also a phenylating agent in this reaction.
- Legros, Jean-Yves,Fiaud, Jean-Claude
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p. 7453 - 7456
(2007/10/02)
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- SINGLE-STEP PREPARATION OF ALLYLIC SULFIDES HAVING 1-PHENYLTETRAZOLE-5-THIO GROUP FROM ALLYLIC ALCOHOLS USING S,S'-BIS(1-PHENYL-1H-TETRAZOL-5-YL) DITHIOCARBONATE AND REACTIONS INVOLVING THE ALLYLIC SULFIDES
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The reaction of allylic alcohols and S,S'-bis(1-phenyl-1H-tetrazol-5-yl) dithiocarbonate (1) gave allylic sulfides having 1-phenyltetrazole-5-thio group in a single step.Furthermore, these allylic sulfides could be applied to carbon-carbon bond and carbon-sulfur bond formations by using Grignard reagents or carbanions in the presence of catalytic amount of copper(I) bromide or palladium (0), respectively.
- Takeda, Kazuyoshi,Tsuboyama, Kanoko,Torii, Katsumi,Murata, Maki,Ogura, Haruo
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p. 4105 - 4108
(2007/10/02)
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- Organic Synthesis with sulfones. XLI. Nucleophilic substitution of allylic sulfones
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The sulfonyl group in allylic sulfones can be displaced by a variety of nucleophiles.The reaction is particularly easy with tertiary sulfones, i.e. bearing no hydrogen atoms at the α-position.Lewis acids catalyse the displacement reaction.
- Julia, Marc,Nel, Maurice,Uguen, Daniel
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p. 487 - 492
(2007/10/02)
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- PALLADIUM-CATALYZED CROSS COUPLING OF ALLYL HALIDES WITH ORGANOTIN REAGENTS: A METHOD OF JOINING HIGHLY FUNCTIONALIZED PARTNERS REGIOSELECTIVELY AND STEREOSPECIFICALLY.
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The palladium-catalyzed reaction of allyl halides with aryl- and vinyltin reagents gives high yields of cross-coupled products. In the presence of 1-3 atm of carbon monoxide, ketones are obtained, resulting from cross coupling accompanied by carbon monoxide insertion. The reaction is mild and tolerant of a wide variety of functionalities (OH, OR, CN, CO//2R, CHO) on either the allyl chloride or the tin reagent. Coupling at the allyl halide partner proceeds with inversion of configuration at the carbon bearing the halide, with retention of geometry at the allylic double bond, and with a regioselectivity for the least-substituted carbon in the allylic framework. Retention of double-bond geometry is observed in the vinyltin partner.
- Sheffy,Godschalx,Stille
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p. 4833 - 4840
(2007/10/11)
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- A CONVENIENT COUPLING REACTION OF ALLYL ALCOHOLS WITH GRIGNARD REAGENTS USING 1-CHLORO-2-METHYL-N,N-TETRAMETHYLENEPROPENYLAMINE
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1-Chloro-2-methyl-N,N-tetramethylenepropenylamine was found to be a good condensation reagent for a regioselective coupling reaction of allyl alcohols with Grignard reagents under mild conditions to afford olefinic products.
- Fujisawa, Tamotsu,Iida, Sachio,Yukizaki, Hisashi,Sato, Toshio
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p. 5745 - 5748
(2007/10/02)
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- Regio- and Stereo-specific Allylation of Grignard Reagents using Allylic Phosphates
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Geranyl and neryl diethyl phosphates are found to react regio- and stereo-specifically with a variety of Grignard reagents giving high yields of coupling products.
- Araki, Shuki,Sato, Takashi,Butsugan, Yasuo
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p. 285 - 286
(2007/10/02)
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