- Design and synthesis of a novel class of nucleotide analogs with anti- HCMV activity
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A novel class of cyclic nucleotide analogs has shown anti-HCMV activity. The synthesis as well as structure - activity relationship studies are presented.
- Nguyen-Ba, Paul,Lee, Nola,Mitchell, Helen,Chan, Laval,Quimpere, Miguel
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- Stereoselective Synthesis of α,α′-Dihydroxy-β,β′-diaryl-β-amino Acids by Mannich-Like Condensation of Hydroarylamides
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Dual α,α′-Dihydroxy-β-amino acids are highly interesting tools for several industrial applications. Nevertheless, only few derivatives are reported in the literature and knowledge concerning the substitution pattern as well as their enantioselective syntheses are lacking. Herein, we report on the preparation of enantiopure α,α′-dihydroxy-β,β′-diaryl-β-amino acid (dual) derivatives by an efficient Mannich-like condensation of hydroarylamides with 5,6-diethoxy-5,6-dimethyl-1,4-dioxan-2-one (triethylsilyl)ketene acetal. The synthetic protocol has been optimized affording the dual compounds in very good yields and with different aryl substitution patterns. Taking advantage of the “double stereodifferentiation” concept, a highly stereoselective reaction was performed: of the 16 possible isomers, only two diastereoisomers (d.r. up to 93:7) formed. Insights into the high stereocontrol of this condensation were given.
- Pecnikaj, Ilir,Foschi, Francesca,Bucci, Raffaella,Gelmi, Maria Luisa,Castellano, Carlo,Meneghetti, Fiorella,Penso, Michele
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supporting information
p. 6707 - 6713
(2019/11/03)
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- Calix[8]arene as New Platform for Cobalt-Salen Complexes Immobilization and Use in Hydrolytic Kinetic Resolution of Epoxides
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Eight cobalt-salen complexes have been covalently attached to a calix[8]arene platform through a flexible linker by a procedure employing Click chemistry. The corresponding well-defined catalyst proved its efficiency in the hydrolytic kinetic resolution (HKR) of various epoxides through an operative bimetallic cooperative activation, demonstrating highly enhanced activity when compared to its monomeric analogue. As an insoluble complex, this multisite cobalt-salen catalyst could be easily recovered and reused in successive catalytic runs. Products were isolated by a simple filtration with virtually no cobalt traces and without requiring a prior purification by flash chromatography.
- Abdellah, Ibrahim,Martini, Cyril,Dos Santos, Amandine,Dragoe, Diana,Guérineau, Vincent,Huc, Vincent,Schulz, Emmanuelle
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p. 4761 - 4767
(2018/10/02)
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- Mixing and matching chiral cobalt- and manganese-based calix-salen catalysts for the asymmetric hydrolytic ring opening of epoxides
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Homochiral oligomeric salen macrocycles possessing aromatic spacers have been prepared as new calix-salen derivatives. The corresponding cobalt and manganese complexes were synthesized and characterized, and their catalytic activities have been studied in the challenging hydrolysis of meso epoxides. While manganese calix-salen complexes were not active in the studied reactions, the dual heterobimetallic system, using an equimolar combination of cobalt and manganese calix-salen derivatives proved to be more enantioselective than the sole cobalt system. Furthermore, as heterogeneous complexes, the catalytic mixture could be easily recovered by simple filtration and successfully reengaged in subsequent catalytic runs. Interestingly, no need for cobalt reactivation was noticed to maintain maximum efficiency of this dual system. The matched Co/Mn dual catalyst was also used to promote the dynamic hydrolytic kinetic resolution of epibromohydrin.
- Dandachi, Hiba,Zaborova, Elena,Kolodziej, Emilie,David, Olivier R.P.,Hannedouche, Jér?me,Mellah, Mohamed,Jaber, Nada,Schulz, Emmanuelle
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p. 246 - 253
(2017/03/01)
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- Chiral calix-salen cobalt complexes, catalysts for the enantioselective dynamic hydrolytic kinetic resolution of epibromohydrin
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New calix-salen cobalt (III) complexes were synthesized as a mixture and as pure trimer or tetramer complexes. These cyclic complexes were used as catalysts to promote the dynamic hydrolytic kinetic resolution (HKR) of epibromohydrin in order to evaluate the effect of the cyclic structures size on the cooperative bimetallic interactions. Since the obtained catalysts were easily recovered from the reaction mixture by simple filtration, their efficiency was evaluated in recycling procedures. It was found that both cyclic oligomer complexes (trimer and tetramer) and the mixture of calix-salen complexes delivered the expected diol with high enantioselectivity and yield. Tetramer calix-salen cobalt complex proved to be the most active and selective catalyst of the series. In this case, an optimal conformation to allow the formation of bimetallic species activating respectively both the epoxide and water as nucleophile is probably responsible for an efficient dual activation.
- Dandachi, Hiba,Nasrallah, Houssein,Ibrahim, Farah,Hong, Xiang,Mellah, Mohamed,Jaber, Nada,Schulz, Emmanuelle
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p. 457 - 462
(2014/12/10)
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- Designed thiazole orange nucleotides for the synthesis of single labelled oligonucleotides that fluoresce upon matched hybridization
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Probe molecules that enable the detection of specific DNA sequences are used in diagnostic and basic research. Most methods rely on the specificity of hybridization reactions, which complicates the detection of single base mutations at low temperature. Significant efforts have been devoted to the development of oligonucleotides that allow discrimination of single base mutations at temperatures where both the match and the mismatch probe-target complexes coexist. Oligonucleotides that contain environmentally sensitive fluorescence dyes such as thiazole orange (TO) provide single nucleotide specific fluorescence. However, most previously reported dye-DNA conjugates showed only little if any difference between the fluorescence of the single and the double stranded state. Here, we introduce a TO-containing acyclic nucleotide, which is coupled during automated oligonucleotide synthesis and provides for the desired fluorescence-up properties. The study reveals the conjugation mode as the most important issue. We show a design that leads to low fluorescence of the unbound probe (background) yet permits TO to adopt fluorescent binding modes after the probe-target complex has formed. In these probes, TO replaces a canonical nucleobase. Of note, the fluorescence of the "TO-base" remains low when a base mismatch is positioned in immediate vicinity.
- Bethge, Lucas,Singh, Ishwar,Seitz, Oliver
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experimental part
p. 2439 - 2448
(2010/07/08)
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- Continuous enantioselective kinetic resolution of terminal epoxides using immobilized chiral cobalt-salen complexes
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Jacobsen's cobalt-salen complex was covalently immobilized on polymer carriers that are part of different technical setups (polymer powder, composite Raschig rings, PASSflow microreactors) and employed for the enantioselective ring opening of terminal epoxides with water and phenols. The polymer-supported catalysts showed good activity and stereoselectivity and could be used repeatedly after a simple reactivation protocol in both batch as well as continuous-flow modes. Georg Thieme Verlag Stuttgart.
- Solodenko, Wladimir,Jas, Gerhard,Kunz, Ulrich,Kirschning, Andreas
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p. 583 - 589
(2007/12/25)
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- Hydrolytic kinetic resolution of epoxides catalyzed by chromium(III)-endo, endo-2,5-diaminonorbornane-salen [Cr(III)-DIANANE-salen] complexes. Improved activity, low catalyst loading
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The hydrolytic kinetic resolution (HKR) of terminal epoxides, using chiral chromium(III)-salen catalysts based on DIANANE (endo,endo-2,5-diaminonorbornane) , was studied. A broad substrate scope was found for the chromium(III)-DIANANE catalysts, and very low loadings (down to 0.05 mol%) were needed to achieve high enantiomeric purities of both the remaining epoxides and the product diols (up to >99% ee). Besides monosubstituted epoxides, 2-methyl-2-n-pentyloxirane, which is an example for 2,2-disubstituted epoxides, could be ring-opened in an asymmetric fashion with water in the presence of an electronically tuned chromium-(III)-DIANANE complex.
- Berkessel, Albrecht,Ertuerk, Erkan
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p. 2619 - 2625
(2007/10/03)
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- Industrialization of the Microbial Resolution of Chiral C3 and C4 Synthetic Units: From a Small Beginning to a Major Operation, a Personal Account
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This account describes the research and development of the microbial resolution of chiral C3 and C4 synthetic units through to the production stage. These chiral C3 and C4 synthetic units are mainly used for the production of various pharmaceuticals, new materials such as liquid crystals, chiral polymers, and natural compounds as well as in basic chemical research. The research started in 1983 and the industrial plant was built in 1994. The development is still ongoing and is being broadened to include C4 chiral units, chiral propylene glycol, and so on. This project started as simple research on the activated sludge from an epichlorohydrin plant and evolved through many events and much research to an industrial production. We describe the various implications and the flow of events in the research and development through to the production of these chiral C3 and C4 synthetic units.
- Kasai, Naoya,Suzuki, Toshio
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p. 437 - 455
(2007/10/03)
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- Highly selective hydrolytic kinetic resolution of terminal epoxides catalyzed by chiral (salen)CoIII complexes. Practical synthesis of enantioenriched terminal epoxides and 1,2-diols
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The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex 1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H2O as a reactant and low loadings (0.2-2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to ≥ 99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring the product ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in several cases are well in excess of 200.
- Schaus, Scott E.,Brandes, Bridget D.,Larrow, Jay F.,Tokunaga, Makoto,Hansen, Karl B.,Gould, Alexandra E.,Furrow, Michael E.,Jacobsen, Eric N.
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p. 1307 - 1315
(2007/10/03)
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- Anti-viral compounds
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Nucleotide analogues having the general formula (I) and pharmaceutically acceptable derivatives: STR1 wherein n is 0 or an integer; X is O or S, CH2, CH-halogen, CH--N3, or C=CH2 ; Q and U are independently selected from: O, S, and CH(Ra) wherein Ra is hydrogen, OH, halogen, N3, NH2, SH, carboxyl, C1-6 alkyl or Ra is CH2 (Rb) wherein Rb is hydrogen, OH, SH, NH2, C1-6 alkyl or carboxyl; or both Q and U are CH when Q and U are linked by a double bond; Z is selected from: O, a C1-6 alkoxy, a C1-6 thioalkyl, a C1-6 aminoalkyl, (CH2)m wherein m is 0 or an integer, and N(Rc)2 wherein both Rc are independently hydrogen or a C1-6, alkyl; and R2 is a purine or pyrimidine base or an analogue or derivative thereof are disclosed. Members of this series of analogues possess anti-viral activity.
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- New polymer supported cinchona alkaloids for heterogeneous catalytic asymmetric dihydroxylation of olefins
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Two new polymeric cinchona alkaloid derived ligands were synthesized and utilized in the asymmetric dihydroxylation of olefins, exhibiting high enantioselectivities in the case of aliphatic terminal olefins under heterogeneous phase.
- Nandanan,Sudalai,Ravindranathan
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p. 2577 - 2580
(2007/10/03)
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- Eine neue Ligandenklasse fuer die asymmetrische Dihydroxylierung von Olefinen
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Keywords: Asymmetrische Dihydroxylierungen; Chirale Liganden; Chinchonaalkaloide; Katalyse; Osmiumverbindungen
- Becker, Heinrich,Sharpless, K. Barry
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p. 447 - 449
(2007/10/03)
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- A novel generation of optically active 1,2-diols from the racemates by using halohydrin dehydro-dehalogenase
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A novel enzyme dehalogenating halohydrins, designated as halohydrin dehydo-dehalogenase (HDDase), was purified from Alcaligenes sp. DS-S-7G. The enzyme catalyzed oxidative dehalogenation of (R)-3-chloro-1,2-propanediol [monochlorohydrin (MCH)] to acetic acid and formaldehyde via hydroxyacetone stereoselectively by the addition of artificial electron acceptors. The dehalogenating activity was much higher in the presence of 2,6- dichlorophenolindophenol (DCIP) and phenazine methosulfate (PMS). The resulting stereoselective dehydro-dehalogenation was applicable to preparation of various optically active halohydrins and 1,2-diols so that the respective residual isomers had excellent enantiomeric excesses (ee) (60-99% ee).
- Suzuki,Kasai,Minamiura
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p. 239 - 246
(2007/10/02)
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- Short and Practical Syntheses of (R)-(-)-Carnitine and (R)-(-)-γ-Amino-β-hydroxybutyric Acid (GABOB)
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Short and practical syntheses of (R)-(-)-carnitine and (R)-(-)-γ-amino-β-hydroxybutyric acid have been developed, both commencing with the catalytic asymmetric dihydroxylation of allyl bromide.
- Kolb, Hartmuth C.,Bennani, Youssef L.,Sharpless, K. Barry
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p. 133 - 141
(2007/10/02)
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- Degradation of 2,3-Dichloro-1-propanol by a Pseudomonas sp.
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A bacterium that assimilates 2,3-dichloro-1-propanol was isolated from soil by enrichment culture.The strain was identified as Pseudomonas sp. by the taxonomic studies.The strain converted 2,3-dichloro-1-propanol to 3-chloro 1,2-propanediol, releasing chloride ions.The conversion was stereospecific because the residual 2,3-dichloro-1-propanol and formed 3-chloro-1,2-propanediol gave optical rotation.The resting cells converted various halohydrins to the dehalogenated alcohols, and cell-free extracts had strong epoxyhydrolase activity.These results indicated that the strain assimilated 2,3-dichloro-1-propanol via 3-chloro-1,2-propanediol, glycidol and glycerol.The possibility to manufacture optically active 2,3-dichloro-1-propanol is discussed.
- Kasai, Naoya,Tsujimura, Kazuya,Unoura, Kinya,Suzuki, Toshio
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p. 3185 - 3190
(2007/10/02)
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