- BCL-2 INHIBITOR
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Disclosed herein is a compound of Formula (I) for inhibiting both Bcl-2 wild type and mutated Bcl-2, in particular, Bcl-2 G101V and D103Y, and a method of using the compound disclosed herein for treating dysregulated apoptotic diseases.
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Paragraph 0571-0573
(2021/10/22)
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- Alcohol Dehydrogenases and N-Heterocyclic Carbene Gold(I) Catalysts: Design of a Chemoenzymatic Cascade towards Optically Active β,β-Disubstituted Allylic Alcohols
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The combination of gold(I) and enzyme catalysis is used in a two-step approach, including Meyer–Schuster rearrangement of a series of readily available propargylic alcohols followed by stereoselective bioreduction of the corresponding allylic ketone intermediates, to provide optically pure β,β-disubstituted allylic alcohols. This cascade involves a gold N-heterocyclic carbene and an enzyme, demonstrating the compatibility of both catalyst types in aqueous medium under mild reaction conditions. The combination of [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene][bis(trifluoromethanesulfonyl)-imide]gold(I) (IPrAuNTf2) and a selective alcohol dehydrogenase (ADH-A from Rhodococcus ruber, KRED-P1-A12 or KRED-P3-G09) led to the synthesis of a series of optically active (E)-4-arylpent-3-en-2-ols in good yields (65–86 %). The approach was also extended to various 2-hetarylpent-3-yn-2-ol, hexynol, and butynol derivatives. The use of alcohol dehydrogenases of opposite selectivity led to the production of both allyl alcohol enantiomers (93->99 % ee) for a broad panel of substrates.
- González-Granda, Sergio,Lavandera, Iván,Gotor-Fernández, Vicente
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supporting information
p. 13945 - 13951
(2021/04/22)
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- Rhodium-Catalyzed C?H Activation/Annulation Cascade of Aryl Oximes and Propargyl Alcohols to Isoquinoline N-Oxides
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A β-hydroxy elimination instead of common oxidization to carbonyl group in secondary propargyl alcohols was successfully developed to form 2-benzyl substituted isoquinoline N-oxides by a Rhodium-catalyzed C?H activation and annulation cascade, in which moderate to excellent yields (up to 92%) could be obtained under mild reaction conditions, along with good regioselectivity, broad generality and applicability. (Figure presented.).
- Li, Yuan,Fang, Feifei,Zhou, Jianhui,Li, Jiyuan,Wang, Run,Liu, Hong,Zhou, Yu
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supporting information
p. 3305 - 3310
(2021/05/17)
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- Laccase-mediated Oxidations of Propargylic Alcohols. Application in the Deracemization of 1-arylprop-2-yn-1-ols in Combination with Alcohol Dehydrogenases
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The catalytic system composed by the laccase from Trametes versicolor and the oxy-radical TEMPO has been successfully applied in the sustainable oxidation of fourteen propargylic alcohols. The corresponding propargylic ketones were obtained in most cases in quantitative conversions (87–>99 % yield), demonstrating the efficiency of the chemoenzymatic methodology in comparison with traditional chemical oxidants, which usually lead to problems associated with the formation of by-products. Also, the stereoselective reduction of propargylic ketones was studied using alcohol dehydrogenases such as the one from Ralstonia species overexpressed in E. coli or the commercially available evo-1.1.200, allowing the access to both alcohol enantiomers mostly with complete conversions and variable selectivities depending on the aromatic pattern substitution (97–>99 % ee). To demonstrate the compatibility of the laccase-mediated oxidation and the alcohol dehydrogenase-catalyzed bioreduction, a deracemization strategy starting from the racemic compounds was developed through a sequential one-pot two-step process, obtaining a selection of (S)- or (R)-1-arylprop-2-yn-1-ols with excellent yields (>98 %) and selectivities (>98 % ee) depending on the alcohol dehydrogenase employed.
- González-Granda, Sergio,Méndez-Sánchez, Daniel,Lavandera, Iván,Gotor-Fernández, Vicente
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p. 520 - 527
(2019/11/16)
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- Au(I)-catalyzed cycloaddition pathways of non-terminal propargyl substrates
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Novel chiral menthol-based pyridyl nitrone ligands were synthesized and Au(I) coordination of the ligands gave chiral Au(I)–nitrone complexes. 1H NMR studies of the gold(I) coordination experiments with nitrone ligands afforded a convenient method for monitoring complex formation. The catalytic effect of Au(I)–nitrone complexes, shown to tune catalytic systems to produce uncommon products, was evaluated in [2 + 2 + 2] cyclotrimerization and [2 + 4] cyclodimerization reactions of non-terminal propargyl acetals. Alternative gold(I)-catalyzed [2 + 2], [2 + 4] and [3 + 4] cycloaddition reaction pathways of non-terminal propargyl acetals with imine substrates gave a diverse range of N-heterocyclic products. The present screening study demonstrates the potential and the versatility of non-terminal propargyl acetals in gold(I)-catalyzed cycloaddition reactions.
- Siah, Huey-San Melanie,Jónsson, Helgi Freyr,Fiksdahl, Anne
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supporting information
p. 1758 - 1773
(2020/05/25)
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- Transition-Metal-Free Ring Expansion Reactions of Indene-1,3-dione: Synthesis of Functionalized Benzoannulated Seven-Membered Ring Compounds
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A novel ring expansion reaction of indene-1,3-dione with alkynyl ketones under transition-metal-free conditions has been developed. This process offers an efficient and direct way to synthesize benzoannulated seven-membered rings or fused-ring compounds t
- Yao, Qiyi,Kong, Lingkai,Wang, Mengdan,Yuan, Yang,Sun, Ruizhuo,Li, Yanzhong
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supporting information
p. 1744 - 1747
(2018/04/14)
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- Propargyl Alcohols as One-Carbon Synthons: Redox-Neutral Rhodium(III)-Catalyzed C-H Bond Activation for the Synthesis of Isoindolinones Bearing a Quaternary Carbon
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Herein, rhodium(III)-catalyzed C-H activation/subsequent [4 + 1] cyclization reactions between benzamides and propargyl alcohols are reported in which propargyl alcohols serve as unusual one-carbon units. This title transformation led to a series of isoin
- Wu, Xiaowei,Wang, Bao,Zhou, Yu,Liu, Hong
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supporting information
p. 1294 - 1297
(2017/03/23)
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- Regioselective Rh-Catalyzed Hydroformylation of 1,1,3-Trisubstituted Allenes Using BisDiazaPhos Ligand
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The efficient hydroformylation of 1,1,3-trisubstituted allenes is accomplished with low loadings of a Rh catalyst supported by a BisDiazaPhos (BDP) ligand. The ligand identity is key to achieving high regioselectivity, while the mild reaction conditions m
- Eshon, Josephine,Landis, Clark R.,Schomaker, Jennifer M.
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p. 9270 - 9278
(2017/09/22)
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- Synthesis of Alkylidene(gem-Difluorocyclopropanes) from Propargyl Glycolates by a One-Pot Difluorocyclopropenation/Ireland-Claisen Rearrangement Sequence
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A one-pot difluorocyclopropenation/Ireland-Claisen rearrangement sequence applied to readily available propargyl glycolates was developed as a route toward functionalized alkylidene(gem-difluorocyclopropanes). This strategy conveniently avoids the isolation of the unstable 3,3-difluorocyclopropenylcarbinyl glycolates arising from the difluorocyclopropenation. The Ireland-Claisen rearrangement proceeds with high diastereoselectivity and chirality transfer to afford alkylidene(gem-difluorocyclopropanes) incorporating a quaternary stereocenter and a protected glycolic acid moiety, which are useful building blocks for the preparation of functionalized gem-difluorocyclopropanes.
- Ernouf, Guillaume,Brayer, Jean-Louis,Folléas, Beno?t,Demoute, Jean-Pierre,Meyer, Christophe,Cossy, Janine
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p. 3965 - 3975
(2017/04/11)
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- Synthesis of highly substituted γ-butyrolactones by a gold-catalyzed cascade reaction of benzyl esters
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Easily accessible benzylic esters of 3-butynoic acids in a gold-catalyzed cyclization/rearrangement cascade reaction provided 3-propargyl γ-butyrolactones with the alkene and the carbonyl group not being conjugated. Crossover experiments showed that the formation of the new C-C bond is an intermolecular process. Initially propargylic-benzylic esters were used, but alkyl-substituted benzylic esters worked equally well. In the case of the propargylic- benzylic products, a simple treatment of the products with aluminum oxide initiated a twofold tautomerization to the allenyl-substituted g-butyrolactones with conjugation of the carbonyl group, the olefin, and the allene. The synthetic sequence can be conducted stepwise or as a one-pot cascade reaction with similar yields. Even in the presence of the gold catalyst the new allene remains intact.
- Jaimes, Maria Camila Blanco,Ahrens, Alexander,Pfl?sterer, Daniel,Rudolph, Matthias,Hashmi, A. Stephen K.
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supporting information
p. 427 - 433
(2015/02/18)
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- Rh(I)-catalyzed transformation of propargyl vinyl ethers into (E, Z)-dienals: Stereoelectronic role of trans effect in a metal-mediated pericyclic process and a shift from homogeneous to heterogeneous catalysis during a one-pot reaction
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The combination of experiments and computations reveals unusual features of stereoselective Rh(I)-catalyzed transformation of propargyl vinyl ethers into (E,Z)-dienals. The first step, the conversion of propargyl vinyl ethers into allene aldehydes, proceeds under homogeneous conditions via a cyclization-mediated mechanism initiated by Rh(I) coordination at the alkyne. This path agrees well with the small experimental effects of substituents on the carbinol carbon. The key feature revealed by the computational study is the stereoelectronic effect of the ligand arrangement at the catalytic center. The rearrangement barriers significantly decrease due to the greater transfer of electron density from the catalytic metal center to the CO ligand oriented trans to the alkyne. This effect increases electrophilicity of the metal and lowers the calculated barriers by 9.0 kcal/mol. Subsequent evolution of the catalyst leads to the in situ formation of Rh(I) nanoclusters that catalyze stereoselective tautomerization. The intermediacy of heterogeneous catalysis by nanoclusters was confirmed by mercury poisoning, temperature-dependent sigmoidal kinetic curves, and dynamic light scattering. The combination of experiments and computations suggests that the initially formed allene-aldehyde product assists in the transformation of a homogeneous catalyst (or a cocktail of catalysts) into nanoclusters, which in turn catalyze and control the stereochemistry of subsequent transformations.
- Vidhani, Dinesh V.,Krafft, Marie E.,Alabugin, Igor V.
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p. 352 - 364
(2014/01/17)
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- Synthesis of β-sulfanyl ketones via a tandem rearrangement-conjugate addition reaction catalyzed by a Re(V)-oxo complex
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A method for synthesizing β-sulfanyl ketones via a tandem rearrangement and conjugate addition reaction has been developed. This methodology provides access to a range of β-sulfanyl ketones through the rearrangement of propargyl alcohols to the corresponding enones followed by the conjugate addition of unactivated thiols. The one-pot, tandem transformation is catalyzed by ReOCl3(OPPh3)(S(CH3)2) affording aryl and alkyl β-sulfanyl ketones in good to excellent yield.
- Garst, Alyson E.,Badiceanu, Alexandra D.,Nolin, Kristine A.
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supporting information
p. 459 - 461
(2013/02/23)
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- Kinetic resolution of propargylic alcohols via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic propargylic alcohols has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 139. Substituent effect is briefly discussed.
- Chen, Peiran,Zhu, Xiyin
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p. 184 - 188
(2013/10/01)
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- COMPOSITIONS AND METHODS FOR MODULATING LPA RECEPTORS
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The present invention relates to compounds of Formula (1), or pharmaceutically acceptable salts thereof and their pharmaceutical compositions, wherein variables are as defined herein, which are useful as modulators of the activity of lysophosphatidic acid (LPA).
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Page/Page column 89
(2012/10/18)
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- Gold-catalyzed isomerization of unactivated allenes into 1,3-dienes under ambient conditions
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We have developed a gold-catalyzed isomerization of unactivated allenes into 1,3-dienes with nitrosobenzene as an additive. This reaction proceeded almost exclusively at room temperature for highly substituted allenes. The utility of this reaction is manifested by the development of one-pot [4+2]-cycloaddition of allenes and reactive alkenes.
- Ting, Chun-Ming,Hsu, Yi-Ling,Liu, Rai-Shung
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supporting information; experimental part
p. 6577 - 6579
(2012/07/31)
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- A concise access to (polyfluoroaryl)allenes by Cu-catalyzed direct coupling with propargyl phosphates
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A copper-based catalyst system for the direct coupling of polyfluoroarenes with propargyl phosphates has been developed. The catalysis can provide a rapid and concise access to (polyfluoroaryl)allenes, which can be important building blocks for the synthesis of fluorinated functional materials.
- Nakatani, Akihiro,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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experimental part
p. 2586 - 2589
(2012/07/30)
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- Heteropoly compound catalyzed synthesis of both z- and e-α,β- unsaturated carbonyl compounds
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An EZ switch: The cationic species of the heteropoly compounds has a critical impact on the Z/E selectivity of the Meyer-Schuster rearrangement of propargyl alcohols (see scheme). The isolation of the thermodynamically unfavorable Z-α,β-unsaturated carbonyl compounds is notable. The high Z selectivities were obtained at a reaction temperature as high as 50°C.
- Egi, Masahiro,Umemura, Megumi,Kawai, Takuya,Akai, Shuji
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supporting information; body text
p. 12197 - 12200
(2012/01/19)
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- Copper-catalyzed enantioselective propargylic amination of propargylic esters with amines: Copper-allenylidene complexes as key intermediates
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The scope and limitations of the copper-catalyzed propargylic amination of various propargylic esters with amines are presented, where optically active diphosphines such as Cl-MeO-BIPHEP and BINAP work as good chiral ligands. A variety of secondary amines are available as nucleophiles for this catalytic reaction to give the corresponding propargylic amines with a high enantioselectivity. The results of some stoichiometric and catalytic reactions indicate that the catalytic amination proceeds via copper-allenylidene complexes formed in situ, where the attack of amines to the electrophilic γ-carbon atom in the allenylidene complex is an important step for the stereoselection. Investigation of the relative rate constants for the reaction of several para-substituted propargylic acetates with N-methylanilines reveals that the formation of the copper-allenylidene complexes is involved in the rate-determining step. The result of the density functional theory calculation on a model reaction also supports the proposed reaction pathway involving copper-allenylidene complexes as key intermediates. The catalytic procedure presented here provides a versatile and direct method for the preparation of a variety of chiral propargylic amines.
- Hattori, Gaku,Sakata, Ken,Matsuzawa, Hiroshi,Tanabe, Yoshiaki,Miyake, Yoshihiro,Nishibayashi, Yoshiaki
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supporting information; experimental part
p. 10592 - 10608
(2010/09/10)
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- Synthesis of novel 2H,5H-dihydrofuran-3-yl ketones via ISNC reactions
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Unique 1-[2H,5H-dihydrofur-3-yl]ketones have been synthesized from propargylic nitroethers via intramolecular cycloadditions involving silyl nitronates. Various substituent groups were placed on the 2 and 5 positions of the dihydrofuran rings. We examined the scope of the long-range coupling in proton NMR of the oxo-dihydrofuran products. The identities of the diastereomers resulting from the Michael addition/cycloaddition reactions were tentatively assigned for the first time. CAChe MNDO PM5 and CONFLEX programs were engaged to assist with the identification of these stereoisomers. The reaction times and conditions for these oxo-dihydrofurans were found to be different than that of the published dihydrofuranals, which led us to propose a different mechanism.
- Grandbois, Matthew L.,Betsch, Kelsie J.,Buchanan, William D.,Duffy-Matzner, Jetty L.
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supporting information; scheme or table
p. 6446 - 6449
(2011/02/23)
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- Studies on Cu(I)-catalyzed synthesis of simple 3-substituted 1,2-allenes and optically active 2-substituted secondary 2,3-allenols
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The sequential treatment of terminal alkynes or propargylic alcohols with n-BuLi and MOMCl afforded the corresponding propargylic methyl ethers, which would react with primary alkyl Grignard reagents under the catalysis of CuBr to afford 3-substituted 1,2-allenes or 2-substituted secondary 2,3-allenols, respectively. The reaction may be applied to the synthesis of optically active 2-substituted secondary 2,3-allenols with up to >99% ee without any protection to the free hydroxyl group in the starting 4-hydroxy-2-alkynyl methyl ethers.
- Li, Jing,Zhou, Chao,Fu, Chunling,Ma, Shengming
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experimental part
p. 3695 - 3703
(2009/09/05)
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- Gold-catalyzed oxidative cleavage of aryl-substituted alkynyl ethers using molecular oxygen. Simultaneous degradation of C-H and single and triple carbon-carbon bonds under ambient conditions
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We report the gold-catalyzed oxidative cleavage of aryl-substituted alkynyl ethers using molecular oxygen under ambient conditions; the transformation involves a remarkable cleavage of C-H, C-C and CC bonds simultaneously.
- Das, Arindam,Chaudhuri, Rupsha,Liu, Rai-Shung
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supporting information; experimental part
p. 4046 - 4048
(2009/12/08)
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- Alkyne hydrosilylation catalyzed by a cationic ruthenium complex: Efficient and general trans addition
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The complex [Cp*Ru(MeCN)3]PF6 is shown to catalyze the hydrosilylation of a wide range of alkynes, Terminal alkynes afford access to α-vinylsilane products with good regioselectivity. Deuterium labeling studies indicate a clean trans
- Trost, Barry M.,Ball, Zachary T.
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p. 17644 - 17655
(2007/10/03)
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- Scope of enantioselective Palladium(II)-catalyzed aerobic alcohol oxidations with (-)-sparteine
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Evaluation of the substrate scope for Pd(II)/ (-)-sparteine catalyzed aerobic oxidative kinetic resolution of secondary alcohols is disclosed. An improved system is found with use of tert-butyl alcohol solvent in which benzylic and aliphatic alcohols as well as alcohols containing olefins are effectively oxidatively resolved. For substrates that successfully undergo oxidative kinetic resolution, krel values are generally between 10 and 20. Successful scale-up of various substrates to 10-mmol scale is described. Extension to oxidative desymmetrization of 1,3-meso-diols is successful with enantiomeric excesses ranging from 78 to 85%.
- Mandal, Sunil K.,Jensen, David R.,Pugsley, Jacob S.,Sigman, Matthew S.
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p. 4600 - 4603
(2007/10/03)
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- Regio- and stereoselective double addition of anionic C-nucleophiles to cobalt-stabilized acetylenedicarbaldehyde
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Though intrinsically unstable, Gorgues' acetylenedicarbaldehyde is an appealing, highly functional C4 synthon, which can be stabilized by η2 complexation to a Co2(CO)6 unit. In contrast to the homologous dibenzoylacetylene complex, it can be used as a normal, doubly electrophilic, non-conjugated γ-dicarbonyl substrate toward alkyl-, aryl-, and alkynyllithium compounds or magnesium bromides; these anionic C-nucleophiles do not predominantly attack at the metal-carbonyl center. The 1,4-dialkyl- and 1,4-diphenylbut2-yne-1,4-diol products are obtained with significant meso/ dl diastereoselectivity (4-66% de), which can be explained by a simple model based on X-ray diffraction data and MM calculations. The alkyl- and arylmagnesium bromide reactants are more selective than their lithium counterparts. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Sui-Seng, Christine,Soleilhavoup, Michele,Maurette, Luc,Tedeschi, Christine,Donnadieu, Bruno,Chauvin, Remi
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p. 1641 - 1651
(2007/10/03)
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- A general and efficient PIFA mediated synthesis of heterocycle-fused quinolinone derivatives
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A new application of the hypervalent iodine reagent phenyliodine(III)bis(trifluoroacetate) (PIFA) has been developed for the construction of a series of N, O, S-containing heterocycle-fused quinolinone derivatives in a general and efficient way. An altern
- Herrero, M.Teresa,Tellitu, Imanol,Domínguez, Esther,Hernández, Susana,Moreno, Isabel,SanMartín, Raúl
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p. 8581 - 8589
(2007/10/03)
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- Rhodium promoted isomerisation of allylic alkoxides: A new method for enolate anion formation
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Transition metal mediated isomerisation of allylic alkoxides is presented as a new method for enolate anion generation. The scope and limitations of enolate formation with the catalysts [Rh(dppe)(THF)2]+ClO4- and (Ph3P)3RhCl are explored and the synthetic potential of the methodology demonstrated in the stereoselective formation and reactions of certain ketone and aldehyde enolates.
- Gazzard, Lewis J.,Motherwell, William B.,Sandham, David A.
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p. 979 - 993
(2007/10/03)
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- An Internally Activated Tin Hydride with Enhanced Reducing Ability
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Tin hydride 1 is activated for nucleophilic hydride transfer and also for radical chain reduction, depending on solvent.The nucleophilic hydride pathway is favored in methanol, and 1 can be used as a selective reducing agent for ketones.Simple ketones are not reduced in aprotic solvents, but β-hydroxy ketones are activated internally by the hydroxyl group and can be reduced in THF with good control of stereochemistry, as in the conversion from 7 to 9 (30:1 9:8).A catalytic version of the nucleophilic hydride reductions in methanol has been developed using PhSiH3 as the stoichiometric hydride source.Radical chain dehalogenations can also be achieved with 1 at room temperature and without added radical initiators.Simple xanthates are not reduced efficiently in the absence of an initiator, but the reaction proceeds in the presence of AIBN.
- Vedejs, E.,Duncan, S. M.,Haight, A. R.
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p. 3046 - 3050
(2007/10/02)
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- Convenient generation of 1-propynyllithium. One-pot synthesis of acetylenic carbinols from 1,2-dibromopropane and aldehydes and ketones
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Treatment of 1,2-dibromopropane (1) with 3 equiv of lithium diisopropylamide (-60° to 0°C, THF) generates 1-propynyllithium (2), which with aldehydes or ketones affords acetylenic carbinols 3 in 82-96% yields.
- Gribble,Joyner,Switzer
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p. 2997 - 3002
(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)
-
- Use of Magnesium Anthracene * 3 THF in Synthesis: Generation of Grignard Compounds and Other Reactions with Organic Halides
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The course (a), (b), (c) (Scheme 1) of the reaction of magnesium anthracene * 3 THF (1) with organic halides (RX) is dependent on the nature of RX.With alkyl halides in THF 1 reacts as a nucleophile, whereby primary as well as secondary alkyl halides produce dialkyldihydroanthracenes (4-4'') and tertiary alkyl halides yield primarily monoalkyl-substituted dihydroanthracenes (2, 2').With bromo- and iodobenzene in THF 1 reacts predominantly as a radical with H atom abstraction from the solvent affording benzene and 9.The formation of Grignard compounds (5) and anthracene (6), originating from primary and secondary alkyl and aryl halides and 1 in toluene or ether at elevated temperatures, is not caused by the reaction of 1 but by the "active magnesium" (Mg*) formed by decomposition of 1 in these solvents.In contrast, allyl, propargyl, and benzyl halides react with 1 independently of the solvent under mild conditions to produce 5 and 6.Allyl- and the difficultly accessible allenylmagnesium chloride can be prepared in THF at -78 and 0 deg C, respectively, from the corresponding halides and ordinary Mg powder via catalytic amounts of 1.
- Bogdanovic, Borislav,Janke, Nikolaus,Kinzelmann, Hans-Georg
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p. 1507 - 1515
(2007/10/02)
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- Synthesis of Allenylsilanes from Propargyl Carbamates
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Pent-3-yn-2-yl acetate (1) reacts with dimethyl(phenyl)silyl cuprate reagent to give a mixture of allenylsilane and propargylsilane.The corresponding N-phenylcarbamate (4) gives only the allenylsilane.Four other examples of this regioselective reaction are reported.The stereochemistry is largely syn.
- Fleming, Ian,Takaki, Ken,Thomas, Andrew P.
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p. 2269 - 2274
(2007/10/02)
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- Mechanism of the Nitrous Acid-Induced Dealkylation of Trisubstituted (Terminal Isopropylidene) Olefins to Form Acetylenes
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Evidence is presented that the conversion of olefins of type RCH=C(CH3)2 to acetylenes of structure RCCCH3 by the action of sodium nitrite in aqueous acetic acid proceeds by a sequence involving two nitrations, Nef conversion of one nitro group to carb
- Corey, E. J.,Seibel, William L.,Kappos, John C.
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p. 4921 - 4924
(2007/10/02)
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- Palladium-Catalyzed Propargylic vs. Allylic Alkylation
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The relative reactivities of allylic propargylic acetates toward palladium(0)-catalyzed substitution by various nucleophiles were studied bu using three types of model substrates: (a) monofunctional allylic and propargylic acetates with similar structural properties; (b) a bifunctional substrate containing both allyl and propargyl functionalities with no apparent interaction between them; (c) conjugated bifunctional systems, in which the two functionalities may interact with one another.Palladium(0)-catalyzed substitution of propargylic acetates by various carbon nucleophiles was found to be less general than the analogous substitution of allylic acetates.Three modes of reactivity were observed, corresponding to three groups of nucleophiles; (a) stabilized carboanions such as sodium dimethyl malonate, which do not react with propargylic acetates but react readily with allylic acetates; (b) nonstabilized organometallics such as phenylzinc chloride, which react with propargylic and allylic acetates at comparable rates (reaction with the former yielding the allenic product exlusively); and (c) allyl- and allenylstannanes, which react with allylic acetates but do not react with isolated propargylic acetates (except for special cases where the propargylic acetate is also an allylic one).Certain similarities between regioselectivity phenomena in organopalladium and organocopper chemistry are discussed.
- Keinan, Ehud,Bosch, Eric
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p. 4006 - 4016
(2007/10/02)
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- ETHERS D'ENOLS β-LITHIES; SYNTHESES D'ALDEHYDES α-ETHYLENIQUES
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β-Bromoenol ethers readily undergo bromine-lithium exchange with t-butyllithium in ether or THF at -70 deg C.The resulting lithium products react with aldehydes and ketones to produce, after hydrolysis, β-hydroxyenol ethers (basic medium) or α-unsaturated aldehydes (acidic medium).
- Duhamel, Lucette,Tombret, Francis,Mollier, Yves
-
-
- A Case of Highly Diastereoselective Addition to Unsymmetrical Ketones: lk-Addition of (2-Alkenyl)triphenoxytitanium Derivatives
-
(2-Butenyl)-, (4-methyl-2-pentenyl)-, and (2-heptenyl)triphenoxytitanium (2a-c) add to dialkyl, alkyl aryl-, and alkinyl aryl ketones to give high yields of tertiary homoallylic alcohols (5-12), which are diastereomerically enriched up to 98percent.Config
- Seebach, Dieter,Widler, Leo
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p. 1972 - 1981
(2007/10/02)
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- MICROBIALLY MEDIATED ENANTIOSELECTIVE HYDROLYSIS OF RACEMIC ACETATES
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The enantioselective hydrolyses of a series of racemic hydroaromatic acetates by Rhizopus nigricans to produce optically active alcohols are described.A rule predicting the absolute stereochemistry of the resulting alcohols is proposed.
- Kawai, Ken-ichi,Imuta, Mitsuru,Ziffer, Herman
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p. 2527 - 2530
(2007/10/02)
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