- L-(S)-ERYTHRULOSE A NOVEL PRECURSOR TO L-2,3-O-ISOPROPYLIDENE-C3 CHIRONS
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Starting from L-(S)-erythrulose, now available in larger quantities, the preparation of L-(S)-glyceraldehyde, L-(R)-glycerol and L-(S)-methyl glycerate acetonides, via the protected L-(S)-3,4-O-isopropylideneerythrulose, is described.
- Wilde, H. De,Clercq, P. De,Vandewalle, M.,Roeper, H.
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- Quantitative screening of hydrolase libraries using pH indicators: Identifying active and enantioselective hydrolases
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The slowest step in finding a selective hydrolase for synthesis is often the screening step. Researchers must run small test reactions and measure the amounts of stereoisomers formed by HPLC, GC, or NMR. We have developed a colorimetric method to speed up this screening. We quantitatively detect ester hydrolysis using a pH indicator, 4-nitrophenol. We estimate the selectivity by measuring the initial rates of hydrolysis for pure stereoisomers separately. To demonstrate the utility of this method, we screened seventy-two commercial enzymes for enantioselective hydrolysis of racemic solketal butyrate, an important chiral building block. First, we eliminated the twenty hydrolases that did not catalyze hydrolysis of either enantiomer. Next, we measured initial rates of hydrolysis of the pure enantiomers of solketal butyrate. For horse-liver esterase, these initial rates differed by a factor of twelve. Subsequent GC experiments confirmed an enantiomeric ratio of fifteen for this hydrolase. Although this enantioselectivity is moderate, it is the highest enantioselectivity reported for a hydrolysis of solketal esters.
- Janes, Lana E.,Loewendahl, A. Christina,Kazlauskas, Romas J.
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- Kinetic resolution of (R,S)-1,2-isopropylidene glycerol (solketal) ester derivatives by lipases
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A study on the enantioselective hydrolysis of (R,S)-1,2-isopropylidene glycerol (4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane, solketal) octanoate catalyzed by different lipases was carried out. Among them, Pseudomonas sp. lipase proved to be the most effective. It was shown that the ester bearing the longer octanoyl acyl chain is a more suitable substrate for this lipase compared to the acetate counterpart. By properly combining enzyme load, temperature and reaction time, either the (S)-alcohol or the remaining ester could be obtained in moderate to high selectivities. Ethyl acetate was found to be the best solvent for the kinetic resolutions effected by such lipase but our results show that toluene may prove useful.
- MacHado, Antonio C.O.,Da Silva, Angelo A.T.,Borges, Cristiano P.,Simas, Alessandro B.C.,Freire, Denise M.G.
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- A NEW SYNTHETIC APPROACH TO L-2,3-O-ISOPROPYLIDENE-C3 CHIRONS
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Starting from L-ascorbic acid the preparation of L-(S)-glyceraldehyde and L-(R)-glycerol acetonides, and 1,2-O-isoprpylidene-L-threitol is described.
- Marco, Jose L.,Rodriguez, Benjamin
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- Synthesis of (R)- and (S)-isopropylidene glycerol
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The preparation of (R)- and (S)-isopropylidene glycerol 1 of high enantiomeric excess (> 98%) was accomplished through salt formation between their hydrogen phthalates with (S)- and (R)-1-methylbenzylamine [MBA] respectively, selective crystallization of these salts and subsequent regeneration of optically active compounds 1 by saponification. The progress of resolution was followed by HPLC analysis on Chiralcel OJ, after converting the hydrogen phthalates into the corresponding mono methyl esters by diazomethane.
- Pallavicini,Valoti,Villa,Piccolo
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Read Online
- Synthesis of Phosphatidylserine and Its Stereoisomers: Their Role in Activation of Blood Coagulation
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Natural phosphatidylserine (PS), which contains two chiral centers, enhances blood coagulation. However, the process by which PS enhanced blood coagulation is not completely understood. An efficient and flexible synthetic route has been developed to synthesize all of the possible stereoisomers of PS. In this study, we examined the role of PS chiral centers in modulating the activity of the tissue factor (TF)-factor VIIa coagulation initiation complex. Full length TF was relipidated with phosphatidylcholine, and the synthesized PS isomers were individually used to estimate the procoagulant activity of the TF-FVIIa complex via a FXa generation assay. The results revealed that the initiation complex activity was stereoselective and had increased sensitivity to the configuration of the PS glycerol backbone due to optimal protein-lipid interactions.
- Mallik, Suman,Prasad, Ramesh,Bhattacharya, Anindita,Sen, Prosenjit
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supporting information
p. 434 - 439
(2018/05/23)
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- Optically active monoacylglycerols: Synthesis and assessment of purity
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Despite their simple structures, synthesis of 1(or 3)-acyl-sn-glycerols remains a challenge that cannot be ignored because of facile acyl migrations, which not only complicate the synthesis but also make direct GC or HPLC analysis unfeasible. Assessment of the optical purity of monoacylglycerols has, to date, relied almost exclusively on specific rotation data, which are small in value and thus insensitive to impurities. Now, a simple means to "magnify" the small specific rotations has been found, along with practical methods for the measurement of both 1,2-and 1,3-acyl migrations, which offer a convenient and straightforward alternative to Mori's NMR analysis of Mosher esters. With the aid of these methods, a range of conditions for deacetonide removal were examined en route to the synthesis of two natural monoacylglycerols. Refined hydrolysis conditions, along with useful knowledge about the solubility and reactivity of substrates with an ultra long alkyl chain are also presented. Copyright
- Chen, Chao-Yuan,Han, Wei-Bo,Chen, Hui-Jun,Wu, Yikang,Gao, Po
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p. 4311 - 4318
(2013/07/26)
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- An esterase with superior activity and enantioselectivity towards 1,2-O-isopropylideneglycerol esters obtained by protein design
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The Escherichia coli esterase YbfF displays high activity towards 1,2-O-isopropylideneglycerol (IPG) butyrate and IPG caprylate, and prefers the R-enantiomer of these substrates, producing the S-enantiomer of the IPG product in excess. To improve the pote
- Godinho, Luis F.,Reis, Carlos R.,Van Merkerk, Ronald,Poelarends, Gerrit J.,Quax, Wim J.
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supporting information
p. 3009 - 3015
(2013/01/15)
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- Asymmetric synthesis of (4S,5S)-2-oxo-4-phenyloxazolidine-5-carboxylic acid using a 1,2-addition of PhMgBr to an N-sulfinimine derived from (R)-glyceraldehyde acetonide and (S)-t-BSA
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We report an asymmetric synthesis of (4S,5S)-2-oxo-4-phenyloxazolidine-5- carboxylic acid via stereoselective addition of phenylmagnesium bromide (PhMgBr) to an N-sulfinimine derived from (R)-glyceraldehyde acetonide. (S)- and (R)-Glyceraldehyde acetonides, important chiral synthons in synthetic organic chemistry, are prepared from the corresponding epichlorohydrin using an identical synthetic methodology.
- Babu, K. Chandra,Vysabhattar, Raman,Srinivas,Nigam, Satish,Madhusudhan,Mukkanti
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experimental part
p. 2619 - 2624
(2011/01/05)
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- A genetic selection system for evolving enantioselectivity of enzymes
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As an alternative to screening in the directed evolution of enantioselective enzymes, a selection system has been implemented for a lipase-catalyzed hydrolytic kinetic resolution of a chiral ester. The Royal Society of Chemistry.
- Reetz, Manfred T.,Hoebenreich, Horst,Soni, Pankaj,Fernandez, Layla
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scheme or table
p. 5502 - 5504
(2009/04/13)
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- Reductive deprotection of propargyl ether by a SmI2-amine-water system and its application to polymer-supported oligosaccharide synthesis
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A SmI2-amine-water system instantaneously deprotected aryl and alkyl propargyl ethers in a reductive manner. The utility of the propargyl group as a protecting group in oligosaccharide synthesis, and its application to polymer-supported oligosaccharide synthesis is described.
- Manabe, Shino,Ueki, Akiharu,Ito, Yukishige
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p. 5159 - 5161
(2008/12/20)
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- Stereoselective construction of the tricyclic core of neoliacinic acid
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(Chemical Equation Presented) The tricyclic core of the plant-derived sesquiterpene natural product neoliacinic acid was synthesized using a novel synthetic strategy. The pivotal synthetic transformations are construction of the key bicyclic ether-bridged intermediate by sequential deployment of metal carbenoid C-H insertion and ylide-forming reactions and installation of the lactone portion of neoliacinic acid by an acid-catalyzed intramolecular ring-opening reaction of an epoxide with a carboxylic acid.
- Clark, J. Stephen,Baxter, Carl A.,Dossetter, Alexander G.,Poigny, Stephane,Castro, Jose L.,Whittingham, William G.
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p. 1040 - 1055
(2008/09/18)
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- Organocatalytic kinetic resolution of racemic primary alcohols using a chiral 1,2-diamine derived from (S)-proline
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A highly efficient and good enantioselective organocatalytic asymmetric acylation of racemic primary alcohols with acyl chlorides has been achieved catalyzed by a chiral 1,2-diamine derived from (S)-proline.
- Terakado, Dai,Koutaka, Hitomi,Oriyama, Takeshi
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p. 1157 - 1165
(2007/10/03)
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- Enhanced enantioselectivity of Bacillus coagulans in the hydrolysis of 1,2-O-isopropylidene glycerol esters by thermal knock-out of undesired enzymes
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The enantioselective hydrolysis of different (RS)-1,2-O-isopropylidene glycerol esters has been achieved with whole cells of Bacillus coagulans NCIMB 9365 furnishing the (S)-alcohol as the major enantiomer. The reaction is catalysed by a thermostable cell-bound carboxylesterase and improvement of the enantioselectivity has been achieved by heat treatment of the whole cells, which causes the knock-outs a non-enantioselective competing enzyme. Thermally-treated cells hydrolysed (RS)-1,2-O-isopropylidene glycerol esters with high enantioselectivity, the highest enantiomeric ratio (80-100) being observed for the benzoate. The biocatalyst displayed good stability and could be re-used after filtration for 12 cycles before showing significant loss of activity; repeated biotransformation batches allowed the recovery of 9.55 g/L of enantiomerically pure (S)-isopropylideneglycerol benzoate starting from 24.0 g/L of the racemic mixture.
- Romano, Diego,Falcioni, Francesco,Mora, Diego,Molinari, Francesco,Buthe, Andreas,Ansorge-Schumacher, Marion
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p. 841 - 845
(2007/10/03)
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- Oxygenated esters of 4-lodo phenylamino benzhydroxamic acids
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The present invention relates to oxygenated esters of 4-iodophenylamino benzhydroxamic acid derivatives, pharmaceutical compositions and methods of use thereof. The present invention also relates to crystaline forms of oxygenated esters of 4-iodophenylamino benzhydroxamic acid derivatives, pharmaceutical compositions and methods of use thereof.
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- N-(4-substituted phenyl)-anthranilic acid hydroxamate esters
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The present invention relates to oxygenated esters of 4-substituted-phenylamino benzhydroxamic acid derivatives, pharmaceutical compositions and methods of use thereof.
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- Enantioselective hydrolysis of (RS)-isopropylideneglycerol acetate with Kluyveromyces marxianus
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The hydrolysis of (RS)-isopropylideneglycerol acetate with whole cells of the yeast Kluyveromyces marxianus is reported. The biotransformation furnished (R)-isopropylideneglycerol as major enantiomer with good enantioselectivity (E=28) under optimised conditions. The reaction can be performed in an ultrafiltration-membrane reactor allowing for the obtainment of 19.2g/L of enantiomerically pure (R)-isopropylideneglycerol acetate starting from 60g/L of racemic mixture.
- Molinari, Francesco,Cavenago, Kristin Solange,Romano, Andrea,Romano, Diego,Gandolfi, Raffaella
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p. 1945 - 1947
(2007/10/03)
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- Highly enantioselective kinetic resolution of primary alcohols of the type Ph-X-CH(CH3)-CH2OH by Pseudomonas cepacia lipase: Effect of acyl chain length and solvent
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Although lipase from Pseudomonas cepacia (PCL) shows high enantioselectivity towards many secondary alcohols, it usually exhibits only low to moderate enantioselectivity towards primary alcohols. To increase this enantioselectivity, we optimised the reaction conditions for the PCL-catalysed hydrolysis of esters of three chiral primary alcohols: 2-methyl-3-phenyl-1- propanol 1, 2-phenoxy-1-propanol 2 and solketal 3. The enantioselectivity towards 1-acetate increased from E=16 to 38 upon changing the solvent from ethyl ether/phosphate buffer to 30% n-propanol in phosphate buffer and increased again to E ≥190 upon changing the substrate from 1-acetate to 1-heptanoate. The same changes increased the enantioselectivity towards alcohol 2 from E=17 to 70, but did not significantly increase the enantioselectivity towards alcohol 3. The best solvent was similar to the solvent used to crystallise the open form of PCL and likely stabilises the open form of PCL. This stabilisation may increase the enantioselectivity by removing kinetic contributions from a non-enantioselective lid-opening step. We determined the kinetic contribution of the lid-opening step by measuring the interfacial activation of PCL. The activation energy for the PCL-catalysed hydrolysis of ethyl acetate was at least 2.6 kcal/mol lower in the presence of a water-organic solvent interface.
- Mezzetti, Alessandra,Keith, Curtis,Kazlauskas, Romas J.
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p. 3917 - 3924
(2007/10/03)
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- N-(4-substituted phenyl)-anthranilic acid hydroxamate esters
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The present invention relates to oxygenated esters of 4-substituted-phenylamino benzhydroxamic acid derivatives, pharmaceutical compositions, and methods of use thereof.
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Page/Page column 13
(2010/02/06)
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- Synthesis of lipophilic aldehydes and study of their inhibition effect on human digestive lipases.
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[reaction: see text] Novel inhibitors of human digestive lipases, aldehyde dialkyl and alkyl-acyl glycerol analogues, were developed. The inhibitors were prepared starting from 3-(benzyloxy)-1,2-propanediol. The inhibition of human pancreatic and gastric lipases by the aldehyde derivatives was studied using the monolayer technique. (1R)-1-[(Dodecyloxy)methyl]-4-oxobutyl decanoate caused a 50% decrease in HPL and HGL activities at 0.100 and 0.053 molar fractions, respectively.
- Kotsovolou, Stavroula,Verger, Robert,Kokotos, George
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p. 2625 - 2628
(2007/10/03)
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- Mapping the substrate selectivity of new hydrolases using colorimetric screening: Lipases from Bacillus thermocatenulatus and Ophiostoma piliferum, esterases from Pseudomonas fluorescens and Streptomyces diastatochromogenes
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Recent advances in biochemistry and molecular biology have simplified the discovery and preparation of new hydrolases. Although these hydrolases might solve problems in organic synthesis, measuring their selectivity, especially enantioselectivity, remains tedious and time consuming. Recently, we developed a colorimetric screening method to measure the enantioselectivity of hydrolases. Here we apply this rapid screening method to map the substrate selectivity of four new hydrolases: lipases from the thermophilic Bacillus thermocatenulatus (DSM 730, BTL2) and a filamentous fungus Ophiostoma piliferum (NRRL 18917, OPL) and esterases from two bacteria, Pseudomonas fluorescens (SIK-W1, esterase I, PFE) and Streptomyces diastatochromogenes (Tue 20, SDE). We screened a general library of 29 substrates and a chiral library of 23 pairs of enantiomers. All four hydrolases catalysed the hydrolysis of unnatural substrates, but the two lipases accepted a broader range of substrates than the two esterases. As expected, the two lipases favoured more hydrophobic substrates, while the two esterases showed a preference for smaller substrates. Several moderately enantioselective reactions were identified for the solketal esters: BTL2, butyrate, E = 7.9 (R); octanoate, E = 4.9 (R) and 3-bromo-2-methyl propionate methyl esters, PFE, E = 12 (S); SDE, E = 5.6 (S). OPL showed low enantioselectivity toward all substrates tested. The current colorimetric screen could not measure the selectivity for several slow-reacting substrates. Traditional screening identified high enantioselectivity of BTL2 and PFE toward one of these slow substrates, 1-phenylethyl acetate (E>50).
- Liu, Andrew Man Fai,Somers, Neil A.,Kazlauskas, Romas J.,Brush, Terry S.,Zocher, Frank,Enzelberger, Markus M.,Bornscheuer, Uwe T.,Horsman, Geoff P.,Mezzetti, Alessandra,Schmidt-Dannert, Claudia,Schmid, Rolf D.
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p. 545 - 556
(2007/10/03)
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- Application of pig liver esterase catalyzed transesterification in organic media to the kinetic resolution of glycerol derivatives
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The PLE/MPEG catalyzed transesterification of the glycerol ketals rac-1a and rac-1d-f with vinyl propionate in toluene proceeded with good selectivities (E=24-34) and gave the enantiomerically enriched S-alcohols 1a and 1d-f, and the S-esters 2a and 2d-f. High selectivities (E=99 and E≥200) were observed in the transesterification of the glycerol ether rac-3 and its desoxy analog rac-5, both having a secondary hydroxy group, with PLE/MPEG. In transesterifications in organic media PLE exhibited a much higher enantioselectivity than in hydrolysis in water.
- Jungen, Manfred,Gais, Hans-Joachim
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p. 3747 - 3758
(2007/10/03)
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- Synthesis of (S)-1-(1H-indol-4-yloxy)-3[4-(3-methoxyphenyl)-4- hydroxypiperidin-1-yl]-propan-2-ol (LY333068) succinate, and its 3-[14C]- isotopomer based on chiral glycerol-[14C] derivatives
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The 3-[14C]-isotopomer of (S)-1-(1H-indol-4-yloxy)-3-[4-(3- methoxyphenyl)-4-hydroxypiperidin-1-yl]-propan-2-ol (LY333068), a 5HT(1A) antagonist, was prepared in 10 steps and 8.2% radiochemical yield from (L)- serine-[3-14C]. Deamination, esterification, and protection of the resulting diol gave methyl (R)2,2-dimethyl-1,3-dioxolane-4-carboxylate-[3- 14C], as a chiral and radiolabeled building block, which then was subsequently coupled with 4-hydroxyindole and 4-(3-methoxyphenyl)-4- hydroxypiperidine to give the titled product with 99.4% radiochemical purity.
- Czeskis, Boris A.
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p. 465 - 475
(2007/10/03)
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- Optimized double kinetic resolution for the preparation of (S)-solketal
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The lipase AK (lipase from Pseudomonas sp.)-catalysed alcoholysis of racemic solketal (2,2-dimethyl-1,3-dioxolane-4-methanol) esters and acylation of solketal in organic solvents proceeded with E = 20-25. This enabled the preparation of the more reactive (S)-enantiomer with more than 30% total isolated yield (based on the racemate) and 95% ee by a double kinetic resolution strategy consisting of enzymatic acylation-chemical saponification-enzymatic acylation or enzymatic alcoholysis-enzymatic acylation sequences. Numerical calculations and theoretical plots for the optimal termination conversions for the 1st and 2nd resolution steps as well as for the find yields as the function of E is considered.
- Vaenttinen, Eero,Kanerva, Liisa T.
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p. 923 - 933
(2007/10/03)
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- Resolution of isopropylidene-glycerol benzoate by sequential enzymatic hydrolysis and preferential crystallization
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Both enantiomers of isopropylidene-glycerol are prepared from its benzoate ester with enantiomeric excess ≤95% by combined partially stereoselective lipase-catalyzed hydrolysis and preferential crystallization.
- Bianchi, Daniele,Bosetti, Aldo,Golini, Paolo,Cesti, Pietro,Pina, Carlo
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p. 817 - 819
(2007/10/03)
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- Efficient Pathways to (R)- and (S)-5-Hydroxymethyl-2-oxazolidinone and some Derivatives
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2-Oxazolidinones are a very interesting class of compounds due to their various pharmacological effects.Two new syntheses of enantiomerically pure (R)- and (S)-5-hydroxymethyl-2-oxazolidinone have been developed starting with D-mannitol, L-ascorbic acid and (R)- or (S)-malic acid. (R)- and (S)-5-hydroxymethyl-2-oxazolidinone have been used to synthesize some new homochiral 2-oxazolidinone derivatives.
- Danielmeier, Karsten,Steckhan, Eberhard
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p. 1181 - 1190
(2007/10/02)
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- Acetals of Dehydro-L-Ascorbic Acid 2-Hydrazones. Access to the Chiral Building Block (R)-Glycerol Acetonide
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5,6-O-Isopropylidene, cyclohexylidene and benzylidene derivatives of L-threo-2,3-hexodiulosono-1,4-lactone 2-phenylhydrazone were prepared.Reduction of the isopropylidene derivative was followed by treatment with base, and then periodate oxidation and reduction to give (R)-glycerol acetonide.Hydrogen bonding in the hydrazones has a role in forming geometrical isomers. - Key Words Dehydro-L-ascorbic acid hydrazone; Isopropylidene; Cyclohexylidene; Benzylidene; (R)-glycerol acetonide.
- Ashry, E. S. H. El,Rashed, N.,Mousaad, A.
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p. 591 - 596
(2007/10/03)
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- Lipase-catalysed Transesterification in the preparation of Optically Active Solketal
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A lipase-catalysed method for a large-scale preparation of both (R)- ee 99percent) and (S)-solketal (ee 94percent after double resolution) has been described.Separation of the reaction products in the resolution mixture was achieved by extraction/distillation and the unwanted enantiomer was racemized and recycled.
- Vaenttinen, Eero,Kanerva, Liisa T.
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p. 3459 - 3464
(2007/10/02)
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- Synthesis of 1-O-Acylglycerol 2,3-Cyclic Phosphate: Determination of the Absolute Structure of PHYLPA, A Specific Inhibitor of DNA Polymerase α
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Four possible stereoisomers of PHYLPA, a specific inhibitor of DNA polymerase α, were synthesized in enantioselective manners.These isomers were examined for inhibition activity for DNA polymerase α, and the structure of PHYLPA was established as sodium 1-O--sn-glycerol 2,3-cyclic phosphate.
- Kabayashi, Susumu,Tokunoh, Ryosuke,Shibasaki, Masakatsu,Shinagawa, Rumi,Murakami-Murofushi, Kimiko
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p. 4047 - 4050
(2007/10/02)
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- Enzymatic resolution of 2,2-disubstituted-1,3-dioxolane-4-methanol carboxylic esters
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The enantioselectivity of enzymatic hydrolysis of carboxylic esters of various 1,2-ketals of glycerol has been investigated. The influence of the ketal group has been studied. A number of lipases and proteinases have been tested and the best enantioselectivity was obtained with proteinase from Aspergillus oryzae which gave an E-value of 9 with 2,2-dimethyl-1,3-dioxolane-4-methanol butanoate. Variations in the acyl part revealed that butanoyl was optimal. All hydrolysis products have been synthesised in homochiral forms from homochiral starting materials.
- Partali,Melbye,Alvik,Anthonsen
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- EFFICIENT RESOLUTION OF SECONDARY ALCOHOLS, CYANOHYDRINS, AND GLYCEROL ACETALS BY COMPLEXATION WITH THE HOST DERIVED FROM TARTARIC ACID
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Some title hydroxy compounds were resolved efficiently by complexation with the host compounds derived from tartaric acid.
- Toda, Fumio,Matsuda, Shotaro,Tanaka, Koichi
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p. 983 - 986
(2007/10/02)
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- The Synthesis of Optically Pure Epoxyalkyl β-D-Glucosides and β-Cellobiosides as Active-Site Directed Inhibitors of Some β-Glucan Hydrolases
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(2R)- and (2S)-2,3-Epoxypropyl, (3R)- and (3S)-3,4-epoxybutyl and (4S)-4,5-epoxypentyl β-D-glucopyranoside, together with the (3R)- and (3S)-3,4-epoxybutyl β-cellobioside, have been prepared by condensation of a glycosyl bromide with the appropriate enantiomer of a chiral alcohol containing a diol protected as an isopropylidene acetal, and subsequent manipulation of the unmasked diol to the epoxide function.As well, in an improvement to the whole process, both diastereoisomers of the various epoxypropyl and epoxybutyl glycosides were available, from just the one enantiomer of the alcohol by an alternative manipulation of the diol.Finally, precursors to 2,3-epoxy-4-hydroxybutyl β-D-glucosides and β-cellobiosides were prepared in high optical purity by Sharpless asymmetric epoxidation of the appropriate 4-hydroxybutyl-2-enyl glycosides.
- Rodriguez, Evelyn B.,Scally, Gavin D.,Stick, Robert V.
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p. 1391 - 1405
(2007/10/02)
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- FACILE PROCESS FOR ENZYMIC RESOLUTION OF RACEMIC ALCOHOLS
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Lipase-catalyzed esterification of a racemic alcohol with succinic anhydride has been found to proceed enantioselectively to afford succinic acid monoester, which was easily separated from non-reacting alcohol by washing with alkaline solution.This procedure provides a facile method for the optical resolution of racemic alcohols.Keywords: optical resolution; racemic alcohol; lipase; succinic anhydride; 1,3-dioxolane-4-methanol
- Terao, Yoshiyasu,Tsuji, Keiichiro,Murata, Masakazu,Achiwa, Kazuo,Nishio, Toshiyuki,et al.
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p. 1653 - 1655
(2007/10/02)
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- Enatioselective Microbial Reduction of Monoesters of 1,3-Dihydroxypropanone: Synthesis of (S)- and (R)-1,2-O-Isopropylideneglycerol
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The reduction of 3-benzoyloxy-1-hydroxypropanone with bakers' yeast proceeds enantioselectively to afford (S)-3-benzoyloxy-1,2-propanediol, which may be further converted into (S)-(benzoyloxymethyl)oxirane.The bioreduction with fermenting yeast of 1-acetoxy-3-benzyloxypropanones gives (R)-1-benzyloxy-3-acetoxy-2-propanol which can be used for the preparation of both (S)- and (R)-1,2-O-isopropylideneglycerol.
- Aragozzini, Fabrizio,Maconi, Elisabetta,Potenza, Donatella,Scolastico, Carlo
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p. 225 - 227
(2007/10/02)
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- ENZYMATIC ENANTIOSELECTIVE HYDROLYSIS OF 2,2-DIMETHYL-1,3-DIOXOLANE-4-CARBOXYLIC ESTERS
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2,2-dimethyl-1,3-dioxolane-4-carboxylic acid derived chiral building blocks were prepared from substituted α,β-unsaturated acids with high enantiomeric purities by enzymatic hydrolysis of their n.butyl esters.
- Pottie, M.,Eycken, J. Van der,Vandewalle, M.,Dewanckele, J. M.,Roeper, H.
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p. 5319 - 5322
(2007/10/02)
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- SUBSTRATE SPECIFICITY AND ENANTIOSELECTIVITY OF PENICILLINACYLASE CATALYZED HYDROLYSIS OF PHENACETYL ESTERS OF SYNTHETICALLY USEFUL CARBINOLS
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Penicillinacylase from E. coli, immobilized on Eupergit C beads catalyzes the hydrolysis in water/CH3CN 10:1, at pH 7.5 and 23 deg C, of a set of O-phenylacetate esters of primary carbinols.The highest enantioselectivity is observed in the case of the 2,2-dimethyl-1,3-dioxolane-4-methanols structurally related to the penicillin (1) framework.Minor modifications of this basic structure are not altering the acceptability by the enzyme, but significantly decrease the enantioselectivity of the hydrolysis, as does the use of benzene as solvent and Sepharose-bound enzyme.
- Fuganti, Claudio,Grasselli, Piero,Servi, Stefano,Lazzarini, Ameriga,Casati, Paolo
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p. 2575 - 2582
(2007/10/02)
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- Levo and dextro dropropizine having antitussive activity
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The optical isomers of 3-(4-phenyl-1-piperazinyl)-1,2-propanediol, a process for the stereo-selective preparation and pharmaceutical composition containing the same as active principles are described.
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- A Convenient Synthesis of L-(S)-Glyceraldehyde Acetonide from L-Ascorbic Acid
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L-(S)-glyceraldehyde acetonide is easily obtained from L-ascorbic acid by three-step procedure.Since the aldehyde is rather unstable in pure form it is more convenient to use it as an aqueous solution.It was used to synthesize L-(R)-glycerol acetonide, monocyclic-β-lactams, and olefins (by Wittig reaction).
- Hubschwerlen, Christian
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p. 962 - 964
(2007/10/02)
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- A SIMPLE SYNTHESIS OF (R)-GLYCEROL ACETONIDE FROM ASCORBIC ACID
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A simple synthesis of (R)-glycerol acetonide (5) has been developed using (L)-ascorbic acid (1) as a chiral precursor.
- Takano, Seiichi,Numata, Hirotoshi,Ogasawara, Kunio
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p. 327 - 328
(2007/10/02)
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- Method for preparing the optically active isomer of 2,2-[[5-[3-[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,2,3,4-tetrahydro-2,3-naphthalene-diyl]bis(oxy)]bis[N,N-dipropylacetamide]
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A method is provided for preparing the optically active isomer [2R-[2α,3α,5(R*)]]-2,2'-[[5-[3-[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,2,3,4-tetrahydro-2,3-naphthalenediyl]bis(oxy)]bis-[N,N-dipropylacetamide] having the structure STR1 which is useful as an antiarrhythmic agent.
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- Total Synthesis of (R)-Glycerol Acetonide and the Antiepileptic and Hypotensive Drug (-)-γ-Amino-β-hydroxybutyric Acid (GABOB): Use of Vitamin C as a Chiral Starting Material
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Ascorbic acid (Vitamin C) (9) is shown to be a useful, inexpensive chiral starting material for natural products synthesis.It is converted in high yield via two synthetic operations into (R)-glycerol acetonide (7), the more inaccessible enantiomer of glycerol acetonide.Since D-(R)-glyceraldehyde acetonide (4) and the corresponding alcohol 1 have been used in many total syntheses of a wide variety of compounds, the ready availability of the opposite enantiomers L-(S)-glyceraldehyde acetonide (6) and glycerol (7) should be of greate value.As one indication of this potential synthetic utility, the hypotensive, antiepileptic compound (R)-(-)-γ-amino-β-hydroxybutyric acid (GABOB) (8) has been synthesized from ascorbic acid (9) via nine steps in 10percent overall yield.As further evidence of the importance of these synthesis, several useful intermediates for the preparation of the highly active hypotensive agents, the aryloxypropanolamines (5), were prepared from Vitamin C.
- Jung, Michael E.,Shaw, Teresa J.
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p. 6304 - 6311
(2007/10/02)
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