- Pd-Catalyzed Nazarov-Type Cyclization: Application in the Total Synthesis of β-Diasarone and Other Complex Cyclopentanoids
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We describe the palladium-catalyzed Nazarov-type cyclization of easily accessible (hetero)arylallyl acetates to pentannulated (hetero)arenes. This method provides ready access to various types of bi-, tri-, tetra-, and pentacyclic cyclopentanoids under ne
- Singh, Bara,Bankar, Siddheshwar K.,Ramasastry
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p. 1043 - 1048
(2022/02/05)
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- Synthetic and mechanistic studies in enantioselective allylic substitutions catalysed by palladium complexes of a modular class of axially chiral quinazoline-containing ligands
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The application of palladium complexes of a modular series of axially chiral phosphinamine ligands, the Quinazolinaps, to the enantioselective alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate and methyl dimethyl malonate is described.
- Carroll, Anne-Marie,McCarthy, Mary,Lacey, Patrick M.,Saunders, Cormac P.,Connolly, David J.,Farrell, Annette,Rokade, Balaji V.,Goddard, Richard,Fristrup, Peter,Norrby, Per-Ola,Guiry, Patrick J.
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- METHODS AND COMPOSITIONS FOR SUBSTITUTED ARYLCYCLOHEPTANE ANALOGS
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In one aspect, the disclosure relates to methods for preparation of intermediates useful for the preparation of aryl-cycloheptene scaffolds. In a further aspect, the disclosed methods pertain to the preparation of compounds comprising an aryl-cycloheptene
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Paragraph 0235-0236
(2020/03/02)
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- Carbamate-based P,O-ligands for asymmetric allylic alkylations
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Herein we report the design and successful catalytic application of modified Trost-ligands in asymmetric allylic alkylation (AAA) reactions. A small set of carbamate-monophosphine P,O-ligands has been prepared in a straightforward two-step synthetic procedure. After optimization of the reaction conditions, high catalytic activities and excellent enantioselectivity up to >99% have been attained.
- Pálv?lgyi, ádám Márk,Schnürch, Michael,Bica-Schr?der, Katharina
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- Pd/BIPHEPHOS is an Efficient Catalyst for the Pd-Catalyzed S-Allylation of Thiols with High n-Selectivity
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The Pd-catalyzed S-allylation of thiols with stable allylcarbonate and allylacetate reagents offers several advantages over established reactions for the formation of thioethers. We could demonstrate that Pd/BIPHEPHOS is a catalyst system which allows the transition metal-catalyzed S-allylation of thiols with excellent n-regioselectivity. Mechanistic studies showed that this reaction is reversible under the applied reaction conditions. The excellent functional group tolerance of this transformation was demonstrated with a broad variety of thiol nucleophiles (18 examples) and allyl substrates (9 examples), and could even be applied for the late-stage diversification of cephalosporins, which might find application in the synthesis of new antibiotics. (Figure presented.).
- Schlatzer, Thomas,Schr?der, Hilmar,Trobe, Melanie,Lembacher-Fadum, Christian,Stangl, Simon,Schl?gl, Christoph,Weber, Hansj?rg,Breinbauer, Rolf
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supporting information
p. 331 - 336
(2019/11/16)
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- Ligand-Free, Quinoline N-Assisted Copper-Catalyzed Nitrene Transfer Reaction to Synthesize 8-Quinolylsulfimides
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An efficient copper-catalyzed, quinolyl N-directed nitrene transfer reaction to 8-quinolylsulfides was described. A variety of 8-quinolylsulfimides with different functional groups were synthesized in moderate to high yields. The obtained 8-quinolylsulfimides were proved to be promising novel type of bidentate ligands in Pd(II)-catalyzed allylic alkylation.
- Xiao, Xinsheng,Huang, Sanping,Tang, Shanshan,Jia, Guokai,Ou, Guangchuan,Li, Yangyan
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p. 7618 - 7629
(2019/06/27)
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- Spiroketal-Based C2-Symmetric Scaffold For Asymmetric Catalysis
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Provided herein is a compound of formula (I): wherein each R is independently selected from the group consisting of C1-8 alkyl, C1-8 heteroalkyl having 1-4 heteroatoms independently selected from N, O, and S, C3-6 cycloalkyl, 3-10 membered heterocycloalkyl having 1-4 heteroatoms independently selected from N, O, and S, C6-10 aryl, and 5-10 membered heteroaryl having 1-4 heteroatoms independently selected from N, O, and S; each X is independently selected from OH, PAr2, P(O)Ar2, OPAr2, C3-6 cycloalkyl, 3-10 membered heterocycloalkyl having 1-4 heteroatoms independently selected from N, O, and S or each X together form O2PNR′2; Ar is C6-10aryl; and each R′ is independently selected from hydrogen and C1-8 alkyl. Also provided are methods of making and using the compound of formula (I).
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Paragraph 0137
(2019/04/08)
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- Preparation and Application of Amino Phosphine Ligands Bearing Spiro[indane-1,2′-pyrrolidine] Backbone
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P,Nsp3-bidentate chiral ligands bearing spiro[indane-1,2′-pyrrolidine] backbone were prepared in gram scale for the first time. Pd complexes of these air-stable amino phosphine ligands could catalyze asymmetric allylic substitutions of malonate-, alcohol-, and amine-type nucleophiles in up to 97percent ee and 99percent yield. A crystal structure of [Pd(II)(η3-1,3-diphenylallyl)(ligand)]PF6 indicated possible transition states of the catalytic reactions. These ligands are characteristic of a very rigid backbone, which is simple but highly effective. They rival C2-symmetric bisphosphine, P,Nsp2-bidentate, and P,Nsp3-bidentate ligands in tested allylic substitutions. ?
- Feng, Lifei,Jiao, Peng,Li, Hongjie,Li, Shasha,Zhang, Jinxia
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p. 9460 - 9473
(2019/08/26)
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- Ligand's electronegativity controls the sense of enantioselectivity in BIFOP-X palladium-catalyzed allylic alkylations
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Palladium-catalyzed allylic alkylations of sodium dimethyl malonate with 1,3-diphenylallyl acetate, employing BIFOP-H (biphenylbisfencholphosphite) and analogue (i.e. BIFOP-X, X = D, Cl, CN, N3) ligands, all yield (S)-enantiomeric products, while alkylations to cyclohexenyl acetate yield the (R)-enantiomeric C-C coupling product (up to 91% yield, 70% ee). The fluoro derivative BIFOP-F however, "switches" the sense of enantioselectivity, yielding the (R)-enantiomer for 1,3-diphenylallyl acetate and the (S)-enantiomer for the cyclohexenyl acetate (up to 92% yield, 67% ee). Computational analyses of transition structures (M06-2X-D3/def2-TZVP//B3LYP-D3(BJ)/def2-SVP) for these Pd-catalyzed allylic alkylations reproduce the experimental preference of BIFOP-H (and analogue BIFOP-X ligands) for (R)- or (S)-enantiomeric products of 1,3-diphenylallyl or cyclohexenyl acetate, respectively. The "F-switch" of the sense of enantioselectivity from BIFOP-H to BIFOP-F is also apparent computationally and is found (NBO-analyses) to originate from lp(Pd) → σ?(P-O) or lp(Pd) → σ?(P-F) hyperconjugations. The higher electronegativity of F vs. H in BIFOP-X hence controls the sense of enantioselectivity of this Pd-catalyzed allylic alkylation.
- Brüllingen, Eric,Neud?rfl, J?rg-Martin,Goldfuss, Bernd
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supporting information
p. 15743 - 15753
(2019/10/19)
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- Design, Synthesis, and Application of Chiral C2-Symmetric Spiroketal-Containing Ligands in Transition-Metal Catalysis
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We present an expedient and economical route to a new spiroketal-based C2-symmetric chiral scaffold, termed SPIROL. Based on this spirocyclic scaffold, several chiral ligands were generated. These ligands were successfully employed in an array of stereoselective transformations, including in iridium-catalyzed hydroarylations (up to 95 % ee), palladium-catalyzed allylic alkylations (up to 97 % ee), intermolecular palladium-catalyzed Heck couplings (up to 94 % ee), and rhodium-catalyzed dehydroalanine hydrogenation (up to 93 % ee).
- Argüelles, Alonso J.,Sun, Siyuan,Budaitis, Brenna G.,Nagorny, Pavel
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supporting information
p. 5325 - 5329
(2018/03/27)
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- Reducing Diastereomorphous Bis(phosphane oxide) Atropisomers to One Atropisomerically Pure Diphosphane: A New Ligand and a Novel Ligand-Preparation Design
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1,1′-Biphenyl-2,2′-diphosphanes with an achiral bridge spanning C-5 and C-5′ form atropisomers that are enantiomers. Accessing them in an atropisomerically pure form requires resolving a racemic mixture thereof or of a bis(phosphane oxide) precursor. 1,1′-Biphenyl-2,2′-diphosphanes with a homochiral bridge spanning C-5 and C-5′ form atropisomers that are diastereomers. We synthesized the first compound of this kind 1) atropselectively and 2) under thermodynamic control—seemingly a first-time exploit in diphosphane synthesis. The selectivity-inducing step was a high-temperature reduction of two non-interconverting bis(phosphane oxide) atropisomers (60:40 mixture). It furnished the desired diphosphane atropisomerically pure (and atropconvergently because the yield was 67 %). This diphosphane proved worthwhile in Tsuji–Trost allylations, the Hayashi addition of phenylboronic acid to cyclohexenone, and the asymmetric hydrogenation of methyl acetoacetate (up to 95 % yield and 95 % ee).
- Sartorius, Frank,Trebing, Marc,Brückner, Charlotte,Brückner, Reinhard
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supporting information
p. 17463 - 17468
(2017/11/27)
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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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supporting information; experimental part
p. 3168 - 3173
(2012/05/05)
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- PdCl2-catalyzed efficient allylation and benzylation of heteroarenes under ligand, base/acid, and additive-free conditions
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We present a PdCl2-catalyzed protocol for highly efficient allylation and benzylation of a rich variety of N-, O-, and S-containing heteroarenes under base/acid, additive, and ligand-free conditions. The method represents the very few examples
- Yuan, Feng-Quan,Gao, Lian-Xun,Han, Fu-She
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supporting information; experimental part
p. 5289 - 5291
(2011/06/21)
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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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- 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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- Copper-catalyzed substitution reactions of acylal with organomanganese reagents
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A mild method for the copper-catalyzed substitution of aldehyde acylals with organomanganese reagents is reported. This operationally simple C-C bond-forming protocol uses different Cu(I) catalysts. Acylal from trans-cinnamaldehyde furnishes conjugated addition product when reacted with alkyl and aryl organomanganese reagents in presence of 10 mol % of Cu(NCMe) 2 (PPh3)2[BF4] and 2 equivalent of Me3Si-C1 as an accelerator. This reagent can be efficiently used in the substitution of one acetate group of aromatic acylal to form esters in high yield.
- Deshmukh, Madhukar B.,Jadhav, Sunil D.,Kadam, Shashikant V.
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p. 989 - 994
(2008/09/18)
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- Quinolinophane-derived alkyldiphenylphosphines: two homologous P,N-planar chiral ligands for palladium-catalysed allylic alkylation
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Two novel homologous [2]paracyclo[2](5,8)quinolinophane-derived P,N-bidentate planar chiral ligands have been synthesised and their effectiveness in asymmetric catalysis tested in palladium-catalysed allylic malonylation of 1,3-diphenylpropenyl acetate. T
- Ruzziconi, Renzo,Santi, Claudio,Spizzichino, Sara
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p. 1742 - 1749
(2008/02/11)
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- New insights into the mechanism of palladium-catalyzed allylic amination
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A comparative investigation into palladium-catalyzed allylic amination of unsubstituted aziridines and secondary amines has been carried out. The use of NH aziridines as nucleophiles favors formation of valuable branched products in the case of aliphatic allyl acetates. The regioselectivity of this reaction is opposite to that observed when other amines are used as nucleophiles. Our study provides evidence for the palladium-catalyzed isomerization of the branched (kinetic) product formed with common secondary amines into the thermodynamic (linear) product. In contrast, the branched allyl products obtained from unsubstituted aziridines do not undergo the isomerization process. Crossover experiments indicate that the isomerization of branched allylamines is bimolecular and is catalyzed by Pd0. The reaction has significant solvent effect, giving the highest branched-to-linear ratios in THF. This finding can be explained by invoking the intermediacy of σ-complexes, which is consistent with NMR data. The apparent stability of branched allyl aziridines towards palladium-catalyzed isomerization is attributed to a combination of factors that stem from a higher degree of s-character of the aziridine nitrogen compared to other amines. The reaction allows for regio- and enantioselective incorporation of aziridine rings into appropriately functionalized building blocks. The resulting methodology addresses an important issue of forming quaternary carbon centers next to nitrogen. The new insights into the mechanism of palladium-catalyzed allylic amination obtained in this study should facilitate synthesis of complex heterocycles, design of new ligands to control branched-to-linear ratio, as well as absolute stereochemistry of allylamines.
- Watson, Iain D. G.,Yudin, Andrei K.
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p. 17516 - 17529
(2007/10/03)
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- Applications of 4,4′-Me3Si2-BINAP in transition-metal-catalyzed asymmetric carbon-carbon bond-forming reactions
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(Chemical Equation Presented) A recently developed BINAP derivative with trimethylsilyl substituents on the 4- and 4′-positions of the binaphthyl skeleton, 2,2′-bis-(diphenylphosphino)-4,4′-bis(trimethylsilyl)-1, 1′-binaphthyl (tms-BINAP), was used in a variety of transition-metal- catalyzed asymmetric carbon-carbon bond-forming reactions. In π-allylpalladium-mediated reactions, tms-BINAP gave better enantioselectivity than the unsubstituted BINAP, and the origin of the improved enantioselectivity was gained from an X-ray structural study of [Pd(η3-C 3H5)((R)-tms-BINAP)]ClO4.
- Ogasawara, Masamichi,Ngo, Helen L.,Sakamoto, Takeshi,Takahashi, Tamotsu,Lin, Wenbin
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p. 2881 - 2884
(2007/10/03)
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- Unusual Selectivity of Unprotected Aziridines in Palladium-Catalyzed Allylic Amination Enables Facile Preparation of Branched Aziridines
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Functionalized branched aziridines can be prepared in high yields and with high levels of regioselectivity using unprotected aziridines as nitrogen sources in palladium-catalyzed allylic amination. High levels of enantioselectivity can be achieved with BINAP on palladium. This methodology allows for strategic placement of an aziridine-containing fragment within a complex molecule environment for further elaboration. Copyright
- Watson, Iain D. G.,Styler, Sarah A.,Yudin, Andrei K.
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p. 5086 - 5087
(2007/10/03)
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- Kinetic resolution and unusual regioselectivity in palladium-catalyzed allylic alkylations with a chiral P,S ligand
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Effective kinetic resolutions of acyclic allylic acetates and benzoates have been obtained using a palladium/(S)-BINAP(S) catalyst system. Unusually large preferences for the formation of branched alkylation products from 3-but-2-enyl and crotyl substrate
- Faller,Wilt, Jeremy C.,Parr, Jonathan
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p. 1301 - 1304
(2007/10/03)
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- Synthesis of dihydrobenzazaphosphole ligands via an intramolecular cyclisation reaction
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Intramolecular cyclization reaction of 1,3,2-oxazaphospholidines was used for the diastereoselective synthesis of dihydrobenzazaphosphole ligands. These ligands can be employed in either monodonor or bidentane form in asymmetric reactions such as palladium-catalyzed allylic substitution. Synthesis of the C2symmetric diphosphine ligand 9 was also discussed.
- Leung, Wilson,Cosway, Sarah,Jones, Raymond H.V.,McCann, Hannah,Wills, Martin
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p. 2588 - 2594
(2007/10/03)
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- Molybdenum(0) and tungsten(0) catalysts with enhanced reactivity for allylic substitution: Regioselectivity and solvent effects
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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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- Metal-catalyzed acyl transfer reactions of enol esters: Role of Y5(OiPr)13O and (thd)2Y(OiPr) as transesterification catalysts
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(equation presented) Primary and secondary alcohols react with vinyl or isopropenyl acetate at room temperature in the presence of catalytic amounts (0.05-1 mol percent) of Y5(OiPr)13O to give the corresponding esters. In selected cases, the yttrium catalyst promotes the selective O-acylation of amino alcohols without the formation of the amide. Enol esters also react with α-amino acid esters in the absence of a catalyst, at room temperature, to give the corresponding amides.
- Lin, Mei-Huey,RajanBabu
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p. 997 - 1000
(2007/10/03)
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- Novel chiral 1-(ferrocenylalkyl)-(S)-prolinols and their application in enantioselective synthesis
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Diastereomeric ferrocenylphosphine ligands, (-)-(S,R,pS)-BPPF-Pro (3a) and (+)-(S,S,pR)-BPPF-Pro (3b), containing the (S)-prolinol moiety were prepared. A detailed structural elucidation of these ligands was carried out using NMR. The Pd-complexes of these ligands were used for enantioselective catalysis of allylic substitution reactions of rac-(E)-1,3-diphenyl-3- acetoxyprop-1-ene with C-nucleophiles generated from pentan-2,4-dione and dimethyl malonate. A series of chiral ferrocene aminoalcohols with (S)- prolinol moiety (4a-c) were also prepared. The role of the configuration of stereogenic centers for stereoselectivity in diethylzinc addition to benzaldehyde was studied. (C) 2000 Elsevier Science Ltd.
- Gotov, Battsengel,Toma, ?tefan,Sol?ániová, Eva,Cvengro?, Ján
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p. 671 - 675
(2007/10/03)
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- Catalytic activity of allyl-, azaallyl- and diaza-pentadienyllanthanide complexes for polymerization of methyl methacrylate
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A variety of allylic, aza-allylic and 1,5-diazapentadienyllanthanide compounds were synthesized and their polymerization catalysis toward methyl methacrylate were examined. Divalent Sm[1,3-bis(trimethylsilyl)propenyl]2(THF)2 1 and Sm(1,3-diphenylpropenyl)2(THF)2 2 were synthesized by the reaction of potassium 1,3-bis(trimethylsilyl)propenide or potassium 1,3-diphenylpropenide with SmI2. The aza-allyllanthanide compound was synthesized by the reaction of 2-pyridylbenzyllithium with SmCl3 followed by the reaction with LiCH(SiMe3)2 to give (2-pyridylbenzyl)2SmCH(SiMe3)2 3. 1,5-Diazapentadienyllanthanide was prepared by the reaction of K[(C5H4N)2CPh] with YbBr2 to give Yb[(C5H4N)2CPh]2(THF)2 4, which crystalizes monoclinic, space group C2/C (No. 15), with a=35.19(1), b=13.613(3), c=26.552(7) A, β=133.77(1)°, and Z=8. Preparations of divalent samarium and ytterbium complexes with bis(2-pyridylphenylmethyl)dimethylsilane ligand (6 and 7) were carried out by the reaction of dipotassium salt of bis(2-pyridylphenylmethyl)dimethylsilane with SmI2 or YbBr2. By using the resulting compounds 1, 2, 3, 4, 6 and 7 as initiator, we have examined their catalytic activities for the polymerization of methyl methacrylate and found that compounds 6 and 7 are effective to give high molecular weight isotactic polymers.
- Ihara, Eiji,Koyama, Kouji,Yasuda, Hajime,Kanehisa, Nobuko,Kai, Yasushi
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- Palladium-catalysed Asymmetric Allylic Substitution: a Ligand Design Incorporating Steric and Electronic Effects
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Enantiomerically pure ligands containing a 4,5-dihydrooxazole moiety tethered to an auxiliary sulfur or phosphorus donor have been prepared.These ligands have been exploited for palladium-catalysed asymmetric allylic substitution, providing enantioselectivity in the catalytic reaction is discussed in terms of the steric and electronic influences provided by the ligand.
- Allen, Joanne V.,Coote, Steven J.,Dawson, Graham J.,Frost, Christopher G.,Martin, Christopher J.,Williams, Jonathon, M.
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p. 2065 - 2072
(2007/10/02)
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- Asymmetric Synthesis. Asymmetric Catalytic Allylation Using Palladium Chiral Phosphine Complexes
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The general characteristics of asymmetric catalytic allylation are analyzed in terms of the properties of the allyl acetate substrates and of the putative (?-allyl)palladium(II) intermediates.After examining the diastereometric equilibria of a series of + complexes, it was established that anti-disposed ?-allyl substituents are the major source of discrimination and that aryl substituents cause an enhancement of the epimerization rate and also are responsible for the greatest discrimination.The ?-allyl substituents appear to contribute additively to the discrimination, and a sector rule is proposed for predicting diastereomeric equilibrium constants.Under appropriate conditions, it is proposed that the optical yields of asymmetric catalytic allylation can be predicted from the chiral discrimination found for these ?-allyl intermediates.These proposals were tested and optical yields of up to 86percent are reported.Quantitative chemical yields were obtained, catalysis can be performed at 25 degC, and the products are readily transformed into useful chirons.The optical yields are sensitive to the chiral phosphine used but are insensitive to the nature of the nucleophiles that were used.There is an approximate correlation of the optical yield with the previously observed diastereomeric ratio of the corresponding (?-allyl)palladium intermediate.All of the reactions are completely regioselective, and all of the nucleophiles used gave the same prevailing enantiomer of the product for a given chiral phosphine.
- Auburn, Pamela R.,Mackenzie, Peter B.,Bosnich, B.
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p. 2033 - 2046
(2007/10/02)
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