- Incorporation of 2-C-methyl-D-erythritol, a putative isoprenoid precursor in the mevalonate-independent pathway, into ubiquinone and menaquinone of Escherichia coli
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Incorporation of deuterium labelled 2-C-methyl-D-erythritol into isoprenoid side-chains of ubiquinone and menaquinone from Escherichia coli strongly supports the proposed intermediate role of this branched sugar derivative in the mevalonate independent pathway for isoprenoid biosynthesis via glyceraldehyde 3-phosphate and pyruvate.
- Duvold, Tore,Cali, Patrizia,Bravo, Jean-Michel,Rohmer, Michel
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Read Online
- Hydroformylation reaction ligand, hydroformylation catalyst and diol preparation method
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The invention discloses a hydroformylation reaction ligand, a hydroformylation catalyst and a diol preparation method According to the invention, the structural formula of the hydroformylation reaction ligand is shown in the specification, wherein R1 and R2 are mutually independent one of H, aryl or substituted aryl, thienyl, pyrrolyl, thiazolyl, imidazolyl and pyridyl; the ligand disclosed by the invention is high in catalytic activity and good in metal active center stability, by-products of aldehyde in a conventional hydroformylation reaction can be reduced, and linear diol with a high normal/isomer ratio can be obtained by a one-step method; and the method has the advantages of simple and convenient process, low cost and energy consumption, good production safety, high product quality and the like, and is particularly suitable for large-scale industrial production.
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Paragraph 0077-0078
(2021/06/22)
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- MOF-derived hcp-Co nanoparticles encapsulated in ultrathin graphene for carboxylic acids hydrogenation to alcohols
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Highly efficient conversion of carboxylic acids to valuable alcohols is a great challenge for easily corroded non-noble metal catalysts. Here, a series of few-layer graphene encapsulated metastable hexagonal closed-packed (hcp) Co nanoparticles were fabricated by reductive pyrolysis of metal-organic framework precursor. The sample pyrolyzed at 400 °C (hcp-Co@G400) presented outstanding performance and stability for converting a variety of functional carboxylic acids and its turnover frequency was one magnitude higher than that of conventional facc-centered cubic (fcc) Co catalysts. In situ DRIFTS spectroscopy of model reaction acetic acid hydrogenation and DFT calculation results confirm that carboxylic acid initially undergoes dehydroxylation to RCH2CO* followed by consecutive hydrogenation to RCH2CH2OH through RCH2COH*. Acetic acid prefers to vertically adsorb at hcp-Co (0 0 2) facet with a much lower adsorption energy than parallel adsorption at fcc-Co (1 1 1) surface, which plays a key role in decreasing the activation barrier of the rate-determining step of acetic acid dehydroxylation.
- Dong, Mei,Fan, Weibin,Gao, Xiaoqing,Zhu, Shanhui
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p. 201 - 211
(2021/06/03)
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- METHOD FOR PRODUCING ALCOHOL
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PROBLEM TO BE SOLVED: To provide a method for producing selectively alcohol from carboxylic acid under mild conditions. SOLUTION: In the presence of a catalyst with M1 and M2 as metal species supported on a support, a substrate is reduced to produce a corresponding alcohol. (M1 is Rh, Pt, Ru, Ir, or Pd; M2 is Sn, V, Mo, W, or Re; the support is ZrO2, hydroxyapatite, Nb2O5, fluoroapatite, or hydrotalcite; the substrate is the formula 1a, 1b, or 1c). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
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Paragraph 0101-0110
(2020/11/26)
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- SULFONIMIDAMIDE COMPOUNDS AS INHIBITORS OF INTERLEUKIN-1 ACTIVITY
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The present disclosure relates to novel sulfonimidamide compounds and related compounds and their use in treating a disorder responsive to modulation of cytokines such as IL-1β and IL-18, modulation of NLRP3 or inhibition of the activation of NLRP3 or related components of the inflammatory process. (I)
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Paragraph 0561
(2020/02/14)
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- (Meth) acrylic ester and manufacturing method thereof (by machine translation)
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(Meth) acrylic acid ester of [be] hydrophobic properties. (1) (Meth) acrylic ester represented by the formula [a]. R1 Is H or methyl; R3 Alkyl, cycloalkyl, aryl or aralkyl; R21 , R22 , R23 Each independently is H, alkyl or cycloalkyl is not one of at least 2 H; Z1 The divalent chain hydrocarbon substituted of unsubstituted C1 a-20/2, 2 // hetero-substituted of unsubstituted C1 a-20 free of divalent cyclic hydrocarbon or a single bond; Z2 The divalent chain hydrocarbon of C1 c 12 2, Z3 The (R21 R22 R23 ) Coupled with a free cyclic hydrocarbon containing heteroatoms C C - C3 d 10/forming atomic group; n is an integer of 0 - 3; m is an integer of 1 - 18[Drawing] no (by machine translation)
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Paragraph 0058
(2019/12/04)
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- A Diaminopropane Diolefin Ru(0) Complex Catalyzes Hydrogenation and Dehydrogenation Reactions
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New ruthenium (0) complexes with a cooperative diolefin diaminopropane (DAP) or the dehydrogenated iminopropenamide ligand (IPA) were synthesized for comparison with their diaminoethane (DAE)/ diazadiene (DAD) ruthenium analogues. These DAP/IPA complexes are efficient catalysts in dehydrogenation reactions of alkaline aqueous methanol which proceeds under mild conditions (T=70 °C) and of higher alcohols, forming the corresponding carbonate and carboxylates, respectively. The scope of the reaction includes an example of a 1,2-diol as model for biomass derived alcohols. Their catalytic applications are extended to the atom-efficient dehydrogenative coupling of alcohols and amines to amides. The reaction proceeds without any additives and is applicable to the synthesis of formamides from methanol. Moreover, DAP/IPA complexes catalyze the hydrogenation of a series of esters, lactone, ketone, activated olefin, aldehyde and imine substrates. The diaminopropane Ru catalyst exhibits higher activity compared to the dehydrogenated β-ketiminate (IPA) and previously studied DAD/DAE based catalysts. We present studies on their stoichiometric reactivity with relevance to their possible catalytic mechanisms and the isolation and full characterization of key reaction intermediates.
- Casas, Fernando,Trincado, Monica,Rodriguez-Lugo, Rafael,Baneerje, Dipshikha,Grützmacher, Hansj?rg
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p. 5241 - 5251
(2019/11/16)
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- Stereoselective synthesis of alicyclic ketones: A hydrogen borrowing approach
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A highly diastereoselective annulation strategy for the synthesis of alicyclic ketones from diols and pentamethylacetophenone is described. This process is mediated by a commercially available iridium(III) catalyst, and provides efficient access to a wide range of cyclopentane and cyclohexane products with high levels of stereoselectivity. The origins of diastereoselectivity in the annulation reaction have been explored by a series of control experiments, which provides an explanation for how each stereocentre around the newly forged ring is controlled.
- Armstrong, Roly J.,Akhtar, Wasim M.,Frost, James R.,Christensen, Kirsten E.,Stevenson, Neil G.,Donohoe, Timothy J.
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supporting information
(2019/11/13)
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- Synthesis and complete structure determination of a sperm-activating and -attracting factor isolated from the ascidian ascidia sydneiensis
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For the complete structure elucidation of an endogenous sperm-activating and -attracting factor isolated from eggs of the ascidian Ascidia sydneiensis (Assydn-SAAF), its two possible diastereomers with respect to C-25 were synthesized. Starting from ergosterol, the characteristic steroid backbone was constructed by using an intramolecular pinacol coupling reaction and stereoselective reduction of a hydroxy ketone as key steps, and the side chain was introduced by Julia-Kocienski olefination. Comparison of the NMR data of the two diastereomers with those of the natural product led to the elucidation of the absolute configuration as 25S; thus the complete structure was determined and the first synthesis of Assydn-SAAF was achieved.
- Watanabe, Tomohiro,Shibata, Hajime,Ebine, Makoto,Tsuchikawa, Hiroshi,Matsumori, Nobuaki,Murata, Michio,Yoshida, Manabu,Morisawa, Masaaki,Lin, Shu,Yamauchi, Kosei,Sakai, Ken,Oishi, Tohru
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p. 985 - 997
(2018/05/04)
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- METHOD FOR REDUCTION OF ORGANIC MOLECULES
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A method for the reduction organic molecules comprising a Ruthenium-Triphosphine complex with aromatic ligands at the phosphors which are ortho or meta substituted.
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Paragraph 0050; 0052; 0053; 0054; 0055
(2018/02/06)
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- Bipyridine ligand ruthenium complex is carried and its preparation method and application (by machine translation)
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The invention relates to a novel bipyridine is carried ligand ruthenium complex and its preparation method and in the ester compound hydrogenation is the application of the alcohol compound in the reaction. The use of the bipyridine ligand ruthenium complex catalytic hydrogenation is carried ester compound alcohol compound method is characterized in that: in order to ester compound material in an amount of 0.001 - 0.3 μM % bipyridyl is carried ligand ruthenium complex as catalyst, adding esters compound material in an amount of 1 - 10mol % alkali, in the 25 - 100 °C and 1 - 10MPa hydrogen pressure catalytic hydrogenation under the conditions of ester compound corresponding alcohol compound. The invention of the bipyridine ligand ruthenium complex is carried is convenient to prepare, stable structure, in the ester compound in hydrogenation reaction exhibits excellent catalytic activity. This invention has overcome the ester compound or a non-homogeneous phase catalytic hydrogenation system requires high-temperature high-pressure reaction conditions and high defects of the catalyst amount, catalyst consumption is small, mild reaction conditions, the reaction selectivity is good, improves the economy and the safety of the production system. (by machine translation)
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Paragraph 0098; 0099; 0100; 0101; 0104
(2017/04/28)
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- Cobalt versus Osmium: Control of Both trans and cis Selectivity in Construction of the EFG Rings of Pectenotoxin 4
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Catalytic oxidative cyclisation reactions have been employed for the synthesis of the E and F rings of the complex natural product target pectenotoxin 4. The choice of metal catalyst (cobalt- or osmium-based) allowed for the formation of THF rings with either trans or cis stereoselectivity. Fragment union using a modified Julia reaction then enabled the synthesis of an advanced synthetic intermediate containing the EF and G rings of the target.
- Roushanbakhti, Ahria,Liu, Yifan,Winship, Paul C. M.,Tucker, Michael J.,Akhtar, Wasim M.,Walter, Daryl S.,Wrigley, Gail,Donohoe, Timothy J.
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supporting information
p. 14883 - 14887
(2017/10/24)
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- METHODS OF FORMING DIOL COMPOUNDS
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Methods of forming a C4 to C7 diol compound, the methods including a first step of reacting a C4 to C7 dicarboxylic acid with hydrogen (H2) gas on a first heterogeneous catalyst at a first temperature and a first pressure to form a C4 to C7 lactone; and a subsequent step of reacting the lactone with hydrogen (H2) gas on a second heterogeneous catalyst at a second temperature and a second pressure, wherein the second temperature is lower than the first temperature. Also disclosed are methods of forming a solvent, the methods including reacting a C4 to C7 dicarboxylic acid with hydrogen (H2) gas on a first heterogeneous catalyst at a first temperature and a first pressure to form a solvent. Further disclosed herein are methods that include reacting mevalonolactone with hydrogen (H2) gas on a second heterogeneous catalyst at a second temperature and a second pressure to form a diol compound.
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Paragraph 0123
(2017/11/06)
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- Iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones to chiral diols
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We report a protocol for the highly efficient iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones via dynamic kinetic resolution. Using Ir-SpiroPAP (R)-1d as a catalyst, a wide range of chiral diols were prepared in a high yield (80-95%) with a high enantioselectivity (up to 95% ee) under mild reaction conditions. This protocol was used for enantioselective syntheses of (?)-preclamol and a chiral 2,5-disubstituted tetrahydropyran.
- Yang, Xiao-Hui,Yue, Hai-Tao,Yu, Na,Li, Yi-Pan,Xie, Jian-Hua,Zhou, Qi-Lin
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p. 1811 - 1814
(2017/03/09)
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- PROCESS FOR PRODUCING POLYHYDRIC ALCOHOL
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A process for producing a polyhydric alcohol includes a step (I) of hydrogenating hemiacetal having a specific structure to obtain a reaction solution (I), and a step (II) of adding water to the reaction solution (I) obtained in the step (I) and further conducting hydrogenation.
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Paragraph 0062; 0067; 0068
(2016/05/24)
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- Process for producing polyhydric alcohol
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A process for producing a polyhydric alcohol which comprises a step (I) in which a hemiacetal having a specific structure is hydrogenated to obtain a liquid reaction mixture (I) and a step (II) in which water is added to the liquid reaction mixture (I) obtained in the step (I) to further conduct hydrogenation.
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Paragraph 0101; 0102; 0103; 0110; 0111
(2016/10/08)
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- Branched Diol Monomers from the Sequential Hydrogenation of Renewable Carboxylic Acids
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A prominent challenge in replacing petrochemical polymers with bioderived alternatives is the efficient transformation of biomass into useful monomers. In this work, we demonstrate a practical process for the synthesis of multifunctional alcohols from five- and six-carbon acids using heterogeneous catalysts in aqueous media. Design of this process was guided by thermodynamic calculations, which indicate the need for two sequential high-pressure hydrogenations: one, reduction of the acid to a lactone at high temperature; two, further reduction of the lactone to the corresponding diol or triol at low temperature. For example, the conversion of mesaconic acid into (α or β)-methyl-γ-butyrolactone was achieved with 95 % selectivity at a turnover frequency of 1.2 min?1 over Pd/C at 240 °C. Subsequent conversion of (α or β)-methyl-γ-butyrolactone into 2-methyl-1,4-butanediol was achieved with a yield of 80 % with Ru/C at 100 °C. This process is an efficient method for the production of lactones, diols, and triols, all valuable monomers for the synthesis of bioderived branched polyesters.
- Spanjers, Charles S.,Schneiderman, Deborah K.,Wang, Jay Z.,Wang, Jingyu,Hillmyer, Marc A.,Zhang, Kechun,Dauenhauer, Paul J.
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p. 3031 - 3035
(2016/10/11)
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- Aqueous-phase hydrogenation of biomass-derived itaconic acid to methyl-γ-butyrolactone over Pd/C catalysts: Effect of pretreatments of active carbon
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The effect of active carbon pretreatment on the catalytic performance of Pd/C catalysts in the hydrogenation of itaconic acid was studied. The catalysts were prepared by deposition-precipitation and characterized by XRD, BET, NH3-TPD, TEM and F
- Li, Sha,Wang, Xicheng,Liu, Xiaoran,Xu, Guoqiang,Han, Sheng,Mu, Xindong
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- Enantioselective Hydroformylation of 1-Alkenes with Commercial Ph-BPE Ligand
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A rhodium complex, in conjunction with commercially available Ph-BPE ligand, catalyzes the branch-selective asymmetric hydroformylation of 1-alkenes and rapidly generates α-chiral aldehydes. A wide range of terminal olefins including 1-dodecene were examined, and all delivered high enantioselectivity (up to 98:2 er) as well as good branch:linear ratios (up to 15:1). (Chemical Equation Presented).
- Yu, Zhiyong,Eno, Meredith S.,Annis, Alexandra H.,Morken, James P.
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supporting information
p. 3264 - 3267
(2015/07/15)
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- Highly versatile catalytic hydrogenation of carboxylic and carbonic acid derivatives using a Ru-triphos complex: Molecular control over selectivity and substrate scope
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The complex [Ru(Triphos)(TMM)] (Triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane, TMM = trimethylene methane) provides an efficient catalytic system for the hydrogenation of a broad range of challenging functionalities encompassing carboxylic esters, amides, carboxylic acids, carbonates, and urea derivatives. The key control factor for this unique substrate scope results from selective activation to generate either the neutral species [Ru(Triphos)-(Solvent)H2] or the cationic intermediate [Ru(Triphos)-(Solvent)(H)(H2)]+ in the presence of an acid additive. Multinuclear NMR spectroscopic studies demonstrated together with DFT investigations that the neutral species generally provides lower energy pathways for the multistep reduction cascades comprising hydrogen transfer to C=O groups and C-O bond cleavage. Carboxylic esters, lactones, anhydrides, secondary amides, and carboxylic acids were hydrogenated in good to excellent yields under these conditions. The formation of the catalytically inactive complexes [Ru(Triphos)(CO)H2] and [Ru(Triphos)(μ-H)]2 was identified as major deactivation pathways. The former complex results from substrate-dependent decarbonylation and constitutes a major limitation for the substrate scope under the neutral conditions. The deactivation via the carbonyl complex can be suppressed by addition of catalytic amounts of acids comprising non-coordinating anions such as HNTf2 (bis(trifluoromethane)sulfonimide). Although the corresponding cationic cycle shows higher overall barriers of activation, it provides a powerful hydrogenation pathway at elevated temperatures, enabling the selective reduction of primary amides, carbonates, and ureas in high yields. Thus, the complex [Ru(Triphos)(TMM)] provides a unique platform for the rational selection of reaction conditions for the selective hydrogenation of challenging functional groups and opens novel synthetic pathways for the utilization of renewable carbon sources.
- Vom Stein, Thorsten,Meuresch, Markus,Limper, Dominik,Schmitz, Marc,H?lscher, Markus,Coetzee, Jacorien,Cole-Hamilton, David J.,Klankermayer, Jürgen,Leitner, Walter
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supporting information
p. 13217 - 13225
(2015/03/30)
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- Ruthenium complexes of tetradentate bipyridine ligands: Highly efficient catalysts for the hydrogenation of carboxylic esters and lactones
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A new type of readily available, air-stable ruthenium complex of tetradentate bipyridine ligands has been developed. These complexes displayed exceptional efficiency for the hydrogenation of aromatic and aliphatic carboxylic esters and lactones at as low as 10 ppm catalyst loading under very mild conditions. the Partner Organisations 2014.
- Li, Wei,Xie, Jian-Hua,Yuan, Ming-Lei,Zhou, Qi-Lin
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supporting information
p. 4081 - 4085
(2014/10/15)
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- Facile synthesis of versatile enantioenriched α-substituted hydroxy esters through a Bronsted acid catalyzed kinetic resolution
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An efficient synthesis of enantioenriched α-substituted γ-hydroxy esters via a kinetic resolution event is described. Bulky racemic esters in the presence of a chiral Bronsted acid selectively lactonize to yield a recoverable enantioenriched hydroxy ester and lactone. These esters are highly versatile building blocks that can readily be converted to synthetically useful materials.
- Qabaja, Ghassan,Wilent, Jennifer E.,Benavides, Amanda R.,Bullard, George E.,Petersen, Kimberly S.
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p. 1266 - 1269
(2013/05/09)
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- Using heteroaryl-lithium reagents as hydroxycarbonyl anion equivalents in conjugate addition reactions with (S, S)-(+)-pseudoephedrine as chiral auxiliary; Enantioselective synthesis of 3-substituted pyrrolidines
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We have developed an efficient protocol for carrying out the stereocontrolled formal conjugate addition of hydroxycarbonyl anion equivalents to α,β-unsaturated carboxylic acid derivatives using (S,S)-(+)-pseudoephedrine as chiral auxiliary, making use of the synthetic equivalence between the heteroaryl moieties and the carboxylate group. This protocol has been applied as key step in the enantioselective synthesis of 3-substituted pyrrolidines in which, after removing the chiral auxiliary, the heteroaryl moiety is converted into a carboxylate group followed by reduction and double nucleophilic displacement. Alternatively, the access to the same type of heterocyclic scaffold but with opposite absolute configuration has also been accomplished by making use of the regio- and diastereoselective conjugate addition of organolithium reagents to α,β,γ,δ-unsaturated amides derived from the same chiral auxiliary followed by chiral auxiliary removal, ozonolysis, and reductive amination/intramolecular nucleophilic displacement sequence.
- Alonso, Beatriz,Ocejo, Marta,Carrillo, Luisa,Vicario, Jose L.,Reyes, Efraim,Uria, Uxue
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p. 614 - 627
(2013/03/13)
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- Ester hydrogenation catalyzed by a ruthenium(II) complex bearing an N-heterocyclic carbene tethered with an "nH2" group and a DFT study of the proposed bifunctional mechanism
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A ruthenium(II) catalyst containing an NHC-amine (NHC = Nheterocyclic carbene) ligand (C-NH2) catalyzes the H2-hydrogenation of various esters and lactones at 50 °C and 25 bar of H2 pressure, mild reaction conditions compared with other reported catalysts. A maximum turnover frequency of 1510 h-1 for the hydrogenation of phthalide with a conversion of 96% is achieved in 4 h. DFT calculations suggest a concerted, asynchronous bifunctional mechanism for homogeneous ester hydrogenation; a proton transfer step from the N-H group of a ruthenium hydride-amine complex to the carbonyl group has the largest energy barrier in the catalytic cycle. A surprising observation is that methyl pivalate ( tBuCOOCH3) is hydrogenated much more rapidly than is tert-butyl acetate (CH3COOtBu). This is explained by the energetics of the rate-determining step of the proposed Ru-H/N-H bifunctional mechanism.
- O, Wylie W.N.,Morris, Robert H.
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- Direct regiospecific and highly enantioselective intermolecular α-allylic alkylation of aldehydes by a combination of transition-metal and chiral amine catalysts
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The first direct intermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd0 complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific α-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed. Go organic! Direct intermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd0 complexes and simple chiral amines as co-catalysts is disclosed (see scheme). Copyright
- Afewerki, Samson,Ibrahem, Ismail,Rydfjord, Jonas,Breistein, Palle,Cordova, Armando
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p. 2972 - 2977
(2012/04/11)
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- INDANE ESTROGEN RECEPTOR MODULATORS AND USES THEREOF
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Described herein are compounds that are estrogen receptor modulators. Also described are pharmaceutical compositions and medicaments that include the compounds described herein, as well as methods of using such estrogen receptor modulators, alone and in combination with other compounds, for treating diseases or conditions that are mediated or dependent upon estrogen receptors.
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Page/Page column 94-95
(2012/01/06)
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- ESTROGEN RECEPTOR MODULATORS AND USES THEREOF
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Described herein are compounds that are estrogen receptor modulators. Also described are pharmaceutical compositions and medicaments that include the compounds described herein, as well as methods of using such estrogen receptor modulators, alone and in combination with other compounds, for treating diseases or conditions that are mediated or dependent upon estrogen receptors.
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Page/Page column 105; 106
(2012/01/05)
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- The resolution of trans-2,2-dichloro-3-methylcyclopropanecarboxylic acid via crystallization of its salts with (+)- and (-)-α-phenylethylamine, and the transformation of the resulting enantiomers into (R)- and (S)-dimethyl 2-methylsuccinates
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The resolution of trans-2,2-dichloro-3-methylcyclopropanecarboxylic acid trans-1 was achieved by crystallization of its salts with (+)- and (-)-α-phenylethylamine. The chiral acids were converted into methyl esters 9, which upon reaction with sodium methoxide in methanol underwent a three-carbon ring cleavage, leading to the corresponding mono-orthoester derivatives 10. Acidic hydrolysis then gave the known (R)- and (S)-dimethyl 2-methylsuccinates 12.
- Kovalenko, Vitaly N.,Kulinkovich, Oleg G.
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experimental part
p. 26 - 30
(2011/04/18)
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- Chemo-biological preparation of the chiral building block (R)-4-acetoxy-2-methyl-1-butanol using Pseudomonas putida
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In order to develop new methyl substituted chiral building blocks which are useful for the synthesis of methyl branched natural products, the enantioselective bioreduction of an exo-methylene to a methyl group was investigated. 4-Acetoxy-2-methylene-1-butanol 3 was prepared from itaconic acid over four steps and converted to the chiral alcohol (R)-4-acetoxy-2-methyl-1- butanol 4, by growing cells of Pseudomonas putida. The bioconversion achieved a high enantioselectivity (92% ee) and a high chemical yield (65%) within a relatively short reaction time (18-20 h). Copyright
- Kim, Youngju,Watanabe, Hidenori,Kim, Bieong-Kil,Seu, Young-Bae
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p. 1658 - 1661
(2012/01/13)
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- Mechanism of the hydrogenolysis of ethers over silica-supported rhodium catalyst modified with rhenium oxide
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The Rh-ReOx/SiO2 (Re/Rh = 0.5) exhibited high activity in the hydrogenolysis of ethers with an OH group. The CO bond neighboring CH2OH group was selectively dissociated: The hydrogenolysis of tetrahydro-5-methyl-2-furfuryl alcohol and 2-isopropoxyethannol gave 1,5-hexanediol and ethanol + isopropanol, respectively. This tendency suggests the regioselective CO dissociation mechanism via anion intermediate formed by the attack of hydride and the subsequent protonation of the anion.
- Koso, Shuichi,Nakagawa, Yoshinao,Tomishige, Keiichi
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scheme or table
p. 221 - 229
(2011/07/06)
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- Selective and flexible transformation of biomass-derived platform chemicals by a multifunctional catalytic system
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(Figure Presented) A sustainable supply chain: The controlled transformation of the biomassderived platform compounds levulinic acid (LA) and itaconic acid (IA) into the corresponding lactones, diols, or cyclic ethers (see picture) by using a multifunctional molecular catalyst is described.
- Geilen, Frank M. A.,Engendahl, Barhel,Harwardt, Andreas,Marquardt, Wolfgang,Klankermayer, Juergen,Leitner, Walter
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supporting information; experimental part
p. 5510 - 5514
(2010/09/16)
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- Polycarbonates derived from green acids: Ring-opening polymerization of seven-membered cyclic carbonates
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Methyl substituted seven-membered ring carbonates (7CCs), namely, 4-methyl- and 5-methyl-1,3-dioxepan-2-one (α-Me7CC and β-Me7CC), have been synthesized in high yields (up to 70%) upon cyclization of the corresponding α,ω-diols issued from green renewable acids. ("Immortal") ring-opening polymerization of these monomers has been carried out using various catalysts combined with an alcohol acting as a co-initiator and a chain transfer agent. The Lewis acid Al(OTf)3, the organometallic complexes [(BDIiPr)Zn(N(SiMe3)2)] ((BDIiPr) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)-imino)-2-pentene] and [(ONOOtBu)Y(N(SiHMe2)2)(THF)] (ONOO tBu = amino-alkoxy-bis(phenolate)) or the organic 4-N,N-dimethylaminopyridine (DMAP), 1.5.7-triazabicyclo-[4.4.0]dec-5-ene (TBD) or 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine (BEMP) successfully afforded the corresponding poly(α- and β-Me7CC)s with quite good control and activities. The dissymmetry of the monomers raises the question of catalyst selectivity in the ring-opening of the 7CCs. Detailed microstructural analyses of the poly(7CC)s using 1H and 13C NMR and MALDI-ToF-MS techniques revealed (1) the higher regioselectivity with preferential ring-opening at the most hindered oxygen-acyl O-C(O)O bond, that is, closest to the α-Me substituent of the zinc-based system followed by the yttrium, as compared to the lack of selectivity of the aluminum one, in the ring-opening polymerization (ROP) of α-Me7CC; (2) the absence of regioselectivity in the ROP of β-Me7CC, whichever the catalyst system used, most likely as a result of the OC(O)O further remote substitution site; (3) the expected α-hydroxy,ω-alkoxyester chain ends. Differential scanning calorimetry (DSC) analyses of these polymers underlined the influence of the position of the methyl substituent on the glass transition temperature. Noteworthy, this study represents the first synthesis of the β-Me7CC monomer and of the resulting polycarbonates.
- Brignou, Pierre,Priebe Gil, Marcelo,Casagrande, Osvaldo,Carpentier, Jean-Francois,Guillaume, Sophie M.
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experimental part
p. 8007 - 8017
(2011/12/15)
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- The regiochemistry of cyclization of α-sulfenyl-, α-sulfinyl-, and α-sulfonyl-5-hexenyl radicals: Procedures leading to regioselective syntheses of cyclic sulfones and sulfoxides
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A study of the cyclization of α-sulfenyl-, α-sulfinyl-, and α-sulfonyl-5-hexenyl and 5-methyl-5-hexenyl radicals reveals a unique contrast in the mode of ring closure of the radicals. In the case of the 5-hexenyl radicals, the sulfinyl-substituted species displays unexpected regioselectivity relative to its analogues. Thus, while the α-S- and α-SO2-5-hexenyl radicals give measurable and increasing quantities of 6-endo product, the α-sulfinyl species cyclizes with high selectivity (95.5:4.5) via a 5-exo mode. By contrast, ring closure of the 5-methyl-5-hexenyl radicals is found to give substantially the 6-endo product in all cases. It is the α-sulfonyl-5-methyl-5-hexenyl radical that now exhibits high regioselectivity (97.5:2.5) for 6-endo closure: an illustration of the synthetic value of this observation is the independent synthesis of the model cyclohexyl sulfone 61 in high yield. It is found that ring closure under the conditions employed occurs irreversibly in all cases.
- Della, Ernest W.,Graney, Sean D.
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p. 3824 - 3835
(2007/10/03)
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- A concise asymmetric synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate and propionate, the sex pheromones of pine sawflies
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(2S,3S,7S)-3,7-Dimethylpentadecan-2-yl acetate (2) and its propionate analogue (3) are the main sex pheromones of all Neodiprion species and Diprion similes, respectively. Starting from (S)-malic acid and employing a highly chemo-, regio-, and stereoselective tandem ester reduction-epoxide formation-reductive epoxide-opening reaction protocol, an efficient total synthesis of (2S,3S,7S)-2 and -3 is reported herein.
- Huang, Pei-Qiang,Lan, Hong-Qiao,Zheng, Xiao,Ruan, Yuan-Ping
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p. 3964 - 3967
(2007/10/03)
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- Asymmetric synthesis of 2-substituted butane-1,4-diols by hydrogenation of homochiral fumaramide derivatives
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Diastereoselective hydrogenation of homochiral fumaramides 1 derived from (2R)-Oppolzer's sultam was observed by analysis of the 1H NMR spectra of the succinamide mixtures with de's of 77-88%. Reduction of these succinamides using LiAlH4 gave the corresponding (2S)-butane-1,4- diols and established that addition of hydrogen takes place selectively on the re-face of fumaramides 1. The stereoselectivity was confirmed by estimating the ee's from the 19F NMR spectra of the Mosher's diesters of the diols. This methodology was applied to the synthesis of selected pyrrolidine natural products in homochiral form.
- Jawaid, Samaila,Farrugia, Louis J.,Robins, David J.
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p. 3979 - 3988
(2007/10/03)
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- Lipase-catalyzed monoprotection of 1,4-diols in an organic solvent using vinyl benzoate as acyl transfer agent
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Lipase from Mucor miehei (MML) has been selected as the most suitable enzyme to catalyze the efficient monobenzoylation of 1,4-diols using vinyl benzoate as acyl transfer reagent in tert-butyl methyl ether. The regioselectivity of the monobenzoylation of
- Ciuffreda, Pierangela,Casati, Silvana,Santaniello, Enzo
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p. 3663 - 3665
(2007/10/03)
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- Oxabicyclo[3.2.1]oct-6-enes as templates for the stereoselective synthesis of polypropionates: Total synthesis of callystatin a and C19-epi-callystatin A
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The total synthesis of the polyketide natural product callystatin A and its novel analog C19-epi-callystatin A is described. Our strategy features the use of an enantiomerically pure oxabicyclo[3.2.1]oct-6-ene as a template for the stereocontrolled preparation of the C15-C21 polypropionate region.
- Lautens, Mark,Stammers, Timothy A.
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p. 1993 - 2012
(2007/10/03)
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- A new asymmetric synthesis of (R)-3-methylpyrrolidine alkaloids starting from (S)-malic acid
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Diastereoselective methylation of dimethyl (S)-malate (8) followed by two three-step reductive dehydroxylation procedures afforded dimethyl (R)-2-methylsuccinate (16) in 80.2% and 84.7% ee respectively, the later was further transformed into the natural enantiomers of ant venom alkaloids (R)-leptothoracine (1) and (R)-3-methyl-N-(2-phenylethyl)pyrrolidine (2) and (3R, 2'S)-3-methyl-N-(2-methylbutyl)pyrrolidine (3).
- Zheng, Xiao,Huang, Pei Qiang,Ruan, Yuan Ping,Lee, Albert W. M.,Chan, Wing Hong
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p. 1505 - 1518
(2007/10/03)
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- Asymmetric synthesis of 1,3- and 1,3,4-substituted pyrrolidines
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Diastereoselective alkylation of N-acylnorbornene sultams 2 afforded a variety of enantiomerically pure products 3a-3e. Reduction with LiAlH4 (LAH) followed by ditosylation furnished chiral 1,4-ditosylates 5a-5e which underwent a cyclization reaction with primary amines to afford chiral 1,3- and 1,3,4-substituted pyrrolidines. (C) 2000 Elsevier Science Ltd.
- Lin, Jing,Chan, Wing Hong,Lee, Albert W. M.,Wong, Wai Yeung,Huang, Pei Qiang
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p. 2949 - 2951
(2007/10/03)
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- Optical rotation computation, total synthesis, and stereochemistry assignment of the marine natural product Pitiamide A
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We report the joint application of ab initio computations and total synthesis to assign the absolute configuration of a new natural product. The expected specific rotations of the (7S,10R)- and (7R,10R)-isomers of pitiamide A in a CHCl3 solvent continuum model were determined as +8 and -39, respectively, by CADPAC calculations of the electric-dipole-magnetic-dipole polarizability tensor. Total syntheses of these two stereoisomers of the marine metabolite were achieved by a convergent strategy that utilized Evans' oxazolidinone alkylation, a novel water-accelerated modification of Negishi's zirconocene-catalyzed asymmetric carbometalation as well as an unusual segment condensation via Mitsunobu alkylation of a nosyl-activated amide. The experimental optical rotation measurements confirmed the results of the computational optical rotation predictions. On the basis of NMR comparisons, the configuration of pitiamide A was assigned as (7R,10R). These studies highlight the considerable structural significance of [α]D data, but, because the optical rotation of the natural product was different from either synthetic diastereomer, our work serves also as an illustration of potential problems with obtaining accurate experimental [α]D data for natural samples.
- Ribe, Seth,Kondru, Rama K.,Beratan, David N.,Wipf, Peter
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p. 4608 - 4617
(2007/10/03)
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- Total synthesis of cytochalasin D: Total synthesis and full structural assignment of cytochalasin O
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A total synthesis of cytochalasin D 3 is reported in which the key step is an intramolecular Diels-Alder reaction used to close the 11-membered ring simultaneously introducing the required stereochemistry at four of the stereogenic centres, C(4), C(5), C(8) and C(9). The precursor 21 for the Diels-Alder reaction was prepared from the aldehyde 13 by condensation with the dienyl phosphonate 14 to give the triene 15 which, after conversion into the acyl imidazole 17, was used to acylate the pyrrolidinone 18. The unstable pyrrolinone 21 was then generated from the pyrrolidinone by phenylselenation-oxidative elimination and was cyclised by heating in toluene under high dilution conditions to give the macrocyclic triene 22 (25-30%). Selective functionalisation of the double-bonds in this triene was investigated with epoxidation being selective for the 17,18-double-bond and hydroxylation using osmium tetroxide taking place selectively at the 6,7-double-bond. For completion of the synthesis of cytochalasin D 3, the 6,7-diol 26 was converted into the exocyclic alkene 30 by protection and dehydration. Further hydroxylation using osmium tetroxide gave the diol 31 which was taken through to the enone 36 by protection followed by phenylselenation, N-debenzoylation and oxidative elimination. Reduction under Luche's conditions gave the alcohol 37 which was converted into the acetate 41 by acetylation followed by protecting group exchange. Selective deprotection of the vicinal diol and mild oxidation then gave the ketone 43. Final deprotection gave cytochalasin D 3 so completing the first total synthesis of this natural product. During the course of this work, the Diels-Alder adduct 22 was oxidised using an excess of osmium tetroxide to give the tetraol 28. After protection as its bis-acetonide 46, this was converted into the allylic acetate 51 using the chemistry developed during the synthesis of cytochalasin D 3. Selective hydrolysis of the 17,18-acetonide and oxidation under Swern conditions gave the hydroxyketone 53 which on deprotection gave cytochalasin O 54 so confirming the structure of this natural product. The Royal Society of Chemistry 1999.
- Merifield, Eric,Thomas, Eric J.
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p. 3269 - 3283
(2007/10/03)
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- Simple synthesis of both enantiomers of 3-methyl-N-(3-methylbutyl)pyrrolidine
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(S)-3-Methyl-N-(3-methylbutyl)pyrrolidine (1) and its anti-pode (R)-1 have been prepared by reduction of (S)-4,5-dihydro-3-methyl-2(3H)furanone (7) and dimethyl (R)-2-methylsuccinate (11), bromination thereof, and ring closure of the intermediates (S)-9 and R)-9, respectively, with 3-methylbutylamine (10). An alternative synthesis of (A)-1 by mesylation of (R)-8 is also described. Both enantiomers of 1 were obtained in excellent enantiomeric excesses (ee = 96%). VCH Verlagsgesellschaft mbH, 1997.
- Veith, Hans Juergen,Collas, Markus,Zimmer, Reinhold
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p. 391 - 394
(2007/10/03)
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- Hydrocarbonylation of prop-2-en-1-ol to butane-1,4-diol and 2-methylpropan-1-ol catalysed by rhodium triethylphosphine complexes
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The hydrocarbonylation of prop-2-ene-1-ol catalysed by [Rh2(O2CMe)4]-PEt3, which gives [RhH(CO)(PEt3)2] as the active species, has been found to produce predominantly butane-1,4-diol and 2-methylpropan-1-ol with small amounts of 2-methylpropane-1,3-diol and propan-1-ol. Neither 2-methylprop-2-enal nor 2-methylprop-2-en-1-ol are intermediates in the production of 2-methylpropan-1-ol. By carrying out the reaction under a variety of reaction conditions and by using deuterium-labelling studies it was possible to formulate a mechanism for the production of 2-methylpropan-1-ol which involves formation of the vinyl alcohol, 2-methylprop-1-en-1-ol, as the primary product followed by tautomerism and hydrogenation, provided that at least two PEt3 groups are co-ordinated to the rhodium. A dehydration is proposed to occur during the catalytic cycle from a cationic hydroxycarbene intermediate. Using propenyl ethers as substrates similar products are obtained presumably via loss of alcohol rather than dehydration. If less than two PEt3 groups are co-ordinated to rhodium the major branched-chain product from prop-2-en-1-ol is 2-methylpropane-1,3-diol. This is interpreted as indicating that protonation of the acyl intermediate and dehydration of the hydroxycarbene do not occur because of the lower electron density on the acyl O atom.
- Simpson, Michael C.,Currie, Alan W. S.,Andersen, Jo-Ann M.,Cole-Hamilton, David J.,Green, Michael J.
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p. 1793 - 1800
(2007/10/03)
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- Succinimide derivatives. II. Synthesis and antipsychotic activity of N- [4-[4-(1,2-benzisothiazol-3-yl)-1-piperazinyl]butyl]1,2-cis- cyclohexanedicarboximide (SM-9018) and related compounds
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Cyclic imides bearing ω-(4-benzisothiazol-3-yl-1-piperazinyl)alkyl moieties were synthesized and tested for antipsychotic activity. The in vitro binding affinities of these compounds were examined for dopamine 2 (D2) and serotonin 2 (5-HT2) receptor sites. Structure-activity relationships within these series are discussed. One of these compounds, N-[4-[4-(1,2- benzisothiazol-3-yl)-1-piperazinyl]butyl]-1,2-cis-cyclohexanedicarboximide (SM-9018), was found to be more potent and more selective in vivo than tiospirone in its antipsychotic activity. SM-9018 (17) is currently undergoing clinical evaluation as a selective antipsychotic agent.
- Ishizumi,Kojima,Antoku,Saji,Yoshigi
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p. 2139 - 2151
(2007/10/03)
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- Studies on the enantioselectivity of the transesterification of 2-methyl-1,4-butanediol and its derivatives catalyzed by Pseudomonas fluorescens lipase in organic solvents
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The irreversible transesterification of 2-methy-1,4-butanediol 1a and its benzyl ethers 2a and 3a catalyzed by Pseudomonas fluorescens lipase in chloroform was studied, the highest ee (> 98%) having been obtained for the 4-benzyl ether 2a.
- Grisenti,Ferraboschi,Casati,Santaniello
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p. 997 - 1006
(2007/10/02)
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- Asymmetric 1,4-additions to γ-menthyloxybutenolides. Part IV. Two enantioselective syntheses of 2-methyl-1,4-butanediol
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Based on the asymmetric Michael addition to 5(R)- and 5(S)-menthyloxy-2[5H]-furanone two new syntheses of enantiomerically pure R- and S-2-methyl-1,4-butanediol are described.
- Jansen,Feringa
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p. 1367 - 1376
(2007/10/02)
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- The Stereochemistry of Organometallic Compounds. XXXVIII. Regio- and Stereo-control in the Rhodium-Catalysed Hydroformylation of Some Alkenyl Phosphites
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Excellent regiocontrol is achieved in the rhodium-catalysed hydroformylation of some alkenyl phosphites, and good stereocontrol is obtained in the hydroformylation of some cyclohexenyl phosphites.The stereochemical results have implications for the mechanism of these rhodium-catalysed reactions.
- Jackson, W. Roy,Moffat, Mark R.,Perlmutter, Patrick,Tasdelen, E. Elizabeth
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p. 823 - 834
(2007/10/02)
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