- Phosphine-dependent stereoselectivity in the mitsunobu cyclodehydration of 1,2-diols: Stereodivergent approach to triaryl-substituted epoxides
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Triaryl-1,2-ethanediols, readily available from natural mandelic acid, can be stereospecifically converted into their corresponding chiral nonracemic epoxides by means of a Mitsunobu cyclodehydration reaction. Upon selection of the phosphine component in
- Garcia-Delgado, Noemi,Riera, Antoni,Verdaguer, Xavier
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- Total Synthesis of (-)-Disorazole C1
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Disorazoles represent a powerful class of highly potent antitubulin natural products isolated from myxobacteria. Herein, we describe a scalable and robust synthesis of (-)-disorazole C1 with high stereoselectivity, featuring quite simple reaction conditio
- Lizzadro, Luca,Spie?, Oliver,Schinzer, Dieter
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- Efficient resolution of (±)-pantolactone by inclusion crystallization with the use of chiral 1,1,2-triphenylethane-1,2-diol
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Enantioselective formation of crystalline 1 : 1 host - guest complexes with (R)- or (S)-1,1,2-triphenylethane-1,2-diol as a host compound allows efficient preparative resolution of (±)-pantolactone. Optically active pantolactones (98% ee) were obtained in 65 - 67% yield.
- Vinogradov,Kurilov,Ferapontov,Heise
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Read Online
- Reductive coupling between aromatic aldehydes and ketones or imines by copper catalysis
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The copper-catalyzed reductive coupling of two different carbonyl compounds has been achieved. The reaction of aromatic aldehydes and arylketones with a silylboronate in the presence of a catalytic amount of a CuCl-N-heterocyclic carbene (NHC) complex and a stoichiometric amount of alkoxide base yielded cross-coupled 1,2-diol derivatives. A reaction pathway is proposed that involves the catalytic formation of a nucleophilic α-silyloxybenzylcopper(I) species from the aromatic aldehyde and its subsequent coupling with the arylketone. This process was amenable to asymmetric catalysis. This copper catalyst system also enabled the reductive coupling between aromatic aldehydes and imines.
- Takeda, Mitsutaka,Mitsui, Atsuhisa,Nagao, Kazunori,Ohmiya, Hirohisa
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p. 3664 - 3669
(2019/02/14)
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- Preparation method of (S)-(-)-1,1,2-triphenyl-1,2-ethanediol
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The invention relates to a preparation method of (S)-(-)-1,1,2-triphenyl-1,2-ethanediol. The preparation method is characterized by comprising the following steps: respectively dissolving methyl mandelate and phenyl magnesium bromide in solvents to prepare a methyl mandelate solution and a phenyl magnesium bromide solution; feeding the prepared methyl mandelate solution and the prepared phenyl magnesium bromide solution into a first micro-channel reactor respectively through a metering pump so as to perform main reaction, and enabling the reaction solution obtained after the reaction to directly flow into a second micro-channel reactor; feeding an acidic aqueous solution into the second micro-channel reactor through a metering pump so as to perform quenching reaction while the reaction solution flows into the second micro-channel reactor, layering the reaction solution obtained after the quenching reaction, and taking an organic phase; drying the organic phase, and then, performing vacuum concentration; and performing recrystallization with toluene to obtain the finished product (S)-(-)-1,1,2-triphenyl-1,2-ethanediol. The preparation method provided by the invention has the advantages of high yield and fast reaction.
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Paragraph 0013; 0014; 0015; 0016; 0017
(2018/07/30)
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- Homochiral Metal-Organic Frameworks with Tunable Nanoscale Channel Array and Their Enantioseparation Performance against Chiral Diols
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Enantioseparation is an integral process in the pharmaceutical industry, considering the ever-increasing demand for chiral medicine products. As a new material, porous metal-organic frameworks (MOFs) have shown their potential application in this field because their structures are easy to adjust and control. Though chiral recognition between racemic substrates and frameworks has made preliminary progress, discussions of their size-matching effects are rare. Herein with the help of channel-tunable homochiral MOFs (HMOFs), diols of different sizes have been separated in good enantiomeric excess (ee%). In addition, the ee% reaches 67.4% for the first time for diols as large as 1,1,2-triphenyl-1,2-ethanediol, which turns out to be the most effective value so far.
- Zhuo, Chao,Wen, Yuehong,Hu, Shengmin,Sheng, Tianlu,Fu, Ruibiao,Xue, Zhenzhen,Zhang, Hao,Li, Haoran,Yuan, Jigang,Chen, Xi,Wu, Xintao
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supporting information
p. 6275 - 6280
(2017/06/13)
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- Novel biphenyl organocatalysts for iminium ion-catalyzed asymmetric epoxidation
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Two novel chiral biphenyl iminium salts derived from L-acetonamine, containing electron-withdrawing 3,30-substituents on the biphenyl unit, have been prepared and tested as asymmetric catalysts for epoxidation of prochiral alkenes. The results are compared with those achieved using the corresponding unsubstituted system.
- Farah, Mohamed M.,Page, Philip C. Bulman,Buckley, Benjamin R.,Blacker, A. John,Elsegood, Mark R.J.
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p. 758 - 769
(2013/07/27)
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- Catalytic asymmetric bromine-lithium exchange: A new tool to build axial chirality
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We present here the first catalytic desymmetrization of the 2,2′,6,6′-tetrabromobiphenyl 1 and analogues, by a bromine-lithium exchange catalyzed by either diamines or diether derivatives (0.5 equiv.), yielding axially chiral compounds in high yield (up to 89%) and high enantioselectivity (up to 82%).
- Perron, Quentin,Alexakis, Alexandre
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supporting information; experimental part
p. 2611 - 2620
(2011/01/05)
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- Synthesis of macrocyclic precursors of lankacidins using Stille reactions of 4-(2-iodo-alkenyl)azetidinones and related compounds for ring closure
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In the context of a proposed total synthesis of lankacidins, the synthesis of 4-(2-iodo-alkenyl)azetidinones and their participation in Stille coupling reactions have been investigated. 1-tert-Butyldimethylsilyl-4-(2-iodoethenyl) azetidinone was found to
- Brain, Christopher T.,Chen, Anqi,Nelson, Adam,Tanikkul, Nongluk,Thomas, Eric J.
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supporting information; experimental part
p. 6613 - 6625
(2010/10/19)
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- A PROCESS FOR THE PREPARATION OF THE (S)-ENANTIOMER OF OMEPRAZOLE
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A process for the preparation of (S)-omeprazole from racemic omeprazole via the formation of an inclusion complex with (S)-1,1,2-triphenyl-1,2-ethanediol. (S)-Omeprazole is recovered in a substantially optically pure form either in neutral form or as a pharmaceutically acceptable salt or as its solvates including hydrates. The (S)-omeprazole 2[(S)-1,1,2-triphenyl-1,2-ethanediol] inclusion complex is new. This resolution process proceeds with high yields and high optical purity.
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Page/Page column 16-17
(2008/06/13)
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- PROCESS FOR THE PREPARATION OF ATORVASTATIN AND INTERMEDIATES
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A process is provided for preparing (R)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-5-hydroxy-3-oxo-1-heptanoic acid, R-substituted ester 9 comprising: (a) reacting the aldehyde 1 with the enolate form of (S)-2-hydroxy-1,2,2-triphenylethyl acetate substituent in a chelating co-solvent; (b) hydrolysis of (R,S)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-3-hydroxy-1-pentanoic acid, (S)-2-hydroxy-1,2,2-triphenylethyl ester (2a and 2b) using a base, preferably an alkali metal base, preferably in a solvent to form the carboxylic acid 7; (c) treating the acid 7 with a chiral base to form a salt and purifying the salt to obtain enantiomerically enriched (R)-7 chiral base salt; (d) alkylation of the (R)-7 chiral base salt or the free base derived from (R)-7, forming (R)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-5-hydroxy-3-oxo-1-heptanoic acid, R-substituted ester 9 and atorvastatin calcium 6, wherein R is a C1 to C6 alkyl, C6 to C9 aryl or C7 to C10 aralkyl.
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Page/Page column 9
(2008/06/13)
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- Preparation of atorvastatin
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A process for preparing (R)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-5-hydroxy-3-oxo-1-heptanoic acid, tert-butylester comprising: (a) reduction of 5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-3-oxo-1-pentanoic acid, (R)-2-hydroxy-1,2,2-triphenylethyl ester; (b) hydrolysis of (R)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-3-hydroxy-1-pentanoic acid, (R)-2-hydroxy-1,2,2-triphenylethyl ester using an alkali base in a solvent to form the acid; (c) alkylation of the acid forming (R)-5-[2-(4-fluorophenyl)-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrol-1-yl]-5-hydroxy-3-oxo-1-heptanoic acid, tert-butylester.
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Page/Page column 5
(2010/02/14)
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- A chiral synthesis of (-)-spiro[1-azabicyclo[2.2.2]octane-3,5′- oxazolidin-2′-one]: A conformationally restricted analogue of acetylcholine that is a potent and selective α7 nicotinic receptor agonist
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A direct, short chiral synthesis of the selective α7 nicotinic receptor agonist (-)-spiro[1-azabicyclo[2.2.2]-octane-3,5′-oxazolidin- 2′-one] (AR-R17779) is presented. The key step utilized attack of the dianion of the (R)-HYTRA ester [(R)-(+)-2-hydroxy-1,2,2-triphenylethyl acetate] on quinuclidin-3-one, followed by a selective precipitation of the diasteriomeric tertiary alcohol that led to (S)-(-)-AR-R17779 in two additional steps.
- Macor, John E.,Mullen, George,Verhoest, Patrick,Sampognaro, Anthony,Shepardson, Bruce,Mack, Robert A.
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p. 6493 - 6495
(2007/10/03)
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- Intermediates for the synthesis of epothilones and methods for their preparation
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The invention relates to a method of synthesis for a compound of formula (I), wherein R is a heterocyclyl moiety and X1, X2, X3and X4are, independently of each other, protecting groups, which is appropriate for the synthesis of epothilone B and desoxyepothione B.
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Page column 29
(2010/01/30)
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- Total synthesis of (-)-epothilone A
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The total synthesis of (-)-epothilone A by a convergent route is reported. The synthesis of the required key intermediates has been improved with respect to stereoselectivity and availability. The access to ethyl ketone 2 has been significantly improved b
- Schinzer, Dieter,Bauer, Armin,Boehm, Oliver M.,Limberg, Anja,Cordes, Martin
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p. 2483 - 2491
(2007/10/03)
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- Asymmetric synthesis of 3,5-dihydroxy-6(E)-heptenoate-containing HMG-CoA reductase inhibitors
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A 'one-pot' conversion of aldehyde 6 to hydroxyketoester 10 with high enantioselection, culminating in a practical asymmetric synthesis of (3R,5S) isomer of the antihyperlipoproteinemic agent fluvastatin, 1, is described. All four 3,5-dihydroxy-6(E)-heptenoate stereoisomers were prepared in enantiopure form starting from 10, utilizing selective reduction and oxidation methods.
- Tempkin, Orin,Abel, Stephan,Chen, Chung-Pin,Underwood, Russell,Prasad, Kapa,Chen, Kau-Ming,Repic, Oljan,Blacklock, Thomas J.
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p. 10659 - 10670
(2007/10/03)
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- Optical Resolution and Absolute Stereochemistry of trans-2,5-Dimethyl-1-phenyl-1-silacyclopentane
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2,5-Dimethyl-1-phenyl-1-silacyclopentane (DMPSC) has been prepared in good yield, as a mixture of stereoisomers, by the reaction of 2,5-dibromohexane and dichlorophenylsilane with magnesium in tetrahydrofuran.The silane so prepared consists of a ca. 1:1.3
- Dang, Hai-Shan,Roberts, Brian P.,Tocher, Derek A.
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p. 117 - 124
(2007/10/02)
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- The Dolastatins. 17. Synthesis of Dolaproine and Related Diastereoisomers
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A special challenge in accomplishing the total synthesis of dolastatin 10 (1) entailed deducing the absolute configuration of the new β-methoxy-γ-amino acid component dolaproine (2) as 2S,2'R,3'R and devising a stereoselective synthesis.Synthesis of this unusual (S)-proline-derived unit as its N-tert-butoxycarbonyl derivative (9b) and three stereoisomers (9a, 9c, 9d) has been summarized.The diastereoisomers were assembled by an aldol condensation between aldehyde 5, derived from (S)-proline, with chiral propionate 6, followed by methylation and cleavage of the chiral directing ester group by hydrogenolysis to afford methyl ethers 9a-d.The absolute stereochemistry of the diastereoisomers was determined by a combination of X-ray crystallographic analyses (of 9a and lactam 11b formed from isomer 7a) and high-field (400 MHz) NMR studies.By using each of these isomers in a series of dolastatin 10 syntheses the stereochemistry of the dolaproine (2) unit of natural (-)-dolastatin 10 (1) was shown to be 2S,2'R,3'R.
- Pettit, George R.,Singh, Sheo Bux,Herald, Delbert L.,Lloyd-Williams, Paul,Kantoci, Darko,et al.
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p. 6287 - 6295
(2007/10/02)
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- Synthesis of dolastatin 10
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A complicated but extremely important scheme of synthesis has been developed for synthesizing, dolaisoleuine, dolaproine, dolaphenine and dolavaline from readily available starting materials such as Z-(S,S)isoleucine, S-phenylalaline, S-phenylalaninol, S-prolinol, S-mandelate, and S-valine. The requisite amino acids have been combined using several peptide coupling procedures to create pharmaceutically pure dolastatin 10.
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- ASYMMETRIC DIELS-ALDER REACTION CATALYSED BY SOME CHIRAL LEWIS ACIDS
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Diels-Alder reaction between cyclopentadiene and various dienophiles (mainly methacrolein) at -78 deg C was catalysed by various chiral aluminium alcoholates.The catalysts were prepared by reaction of EtAlCl2 with several families of diol (or their monoet
- Rebiere, F.,Riant, O.,Kagan, H.B.
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p. 199 - 214
(2007/10/02)
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- Catalytic asymmetric glyoxylate-ene reaction: A practical access to α-hydroxy esters in high enantiomeric purities
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An efficient asymmetric catalysis is developed for the glyoxylate-ene reaction to afford the α-hydroxy esters of biological and synthetic importance. The key to the success is the use of the chiral titanium complex prepared in situ from (i-PrO)2TiX2 (X = Cl or Br) and the (R)- or (S)-binaphthol in the presence of molecular sieves (MS 4A). The presence of the molecular sieves (zeolite) is clarified to facilitate the alkoxy-ligand exchange reaction. Thus, the use of MS is shown to be essential for the in situ preparation step of the chiral catalyst and not for the ene reaction step. The present catalytic process is applicable to various 1,1-disubstituted olefins by the judicious choice of the dichloro or dibromo catalyst.
- Mikami, Koichi,Terada, Masahiro,Nakai, Takeshi
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p. 3949 - 3954
(2007/10/02)
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- Simple Three-Step Synthesis of (R)- and (S)-4-Amino-3-hydroxybutanoic Acid (GABOB) by Stereoselective Aldol Addition
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A simple synthesis of both (R)- and (S)-GABOB (5) is reported.In the key step, doubly deprotonated (R)- or (S)-2-Hydroxy-1,2,2-triphenylethyl acetate (HYTRA) (1) is added to Cbz-protected glycinal (2).
- Braun, Manfred,Waldmueller, Delia
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p. 856 - 858
(2007/10/02)
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- Stereoselective Aldol Reactions with (R)- and (S)-2-Hydroxy-1,2,2-triphenylethyl Acetate and Related Glycol Monoacetates
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The enolate 7a, formed by double deprotonation of the ester 5a, is added to aldehydes.The influences of the enolate gegenion, of the solvent, and of the reaction temperature on the ratio of the isomeric products 9:10 are studied.The highest degrees of dia
- Devant, Ralf,Mahler, Ulrike,Braun, Manfred
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p. 397 - 406
(2007/10/02)
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- Synthesis of Chiral Phosphate Esters
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A stereospecific route for the synthesis of chiral phosphate monoesters of known absolute configuration is described.
- Cullis, Paul M.,Lowe, Gordon
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p. 2317 - 2321
(2007/10/02)
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