- One Pot Asymmetric Synthesis of (R)-Phenylglycinol from Racemic Styrene Oxide via Cascade Biocatalysis
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(R)-Phenylglycinol is an important chiral building block for pharmaceutical and fine chemical industry, and its efficient synthesis from cheap and commercially available starting materials is challenging and highly desirable. Herein, a new three-step one-pot cascade system employing epoxide hydrolase, glycerol dehydrogenase, and ω-transaminase was designed for the asymmetric synthesis of (R)-phenylglycinol from racemic styrene oxide. A cofactor self-sufficient system employing AlaDH/L?Ala was utilized for the regeneration of expensive cofactor NAD+ and removal of by-product pyruvate. Furthermore, in situ product removal by cation resin adsorption was used to drive the thermodynamic equilibrium of the cascade reaction to the direction of product generation. Finally, optically pure (R)-phenylglycinol was successfully produced from racemic styrene oxide with high yield (81.9 %) and excellent enantioselectivity (99 % ee).
- Sun, Zai-Bao,Zhang, Zhi-Jun,Li, Fu-Long,Nie, Yao,Yu, Hui-Lei,Xu, Jian-He
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- Different enantioselective interaction pathways induced by derivatized quinines
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The stereochemistries in solution of the diastereoisomeric complexes formed by quinines modified at the hydroxyl site (9-O-acetylquinine; 9-O- (3,5-dimethoxyphenylcarbamate)quinine) or quinuclidine nitrogen (N- benzylquininium chloride) and each enantiomer of 2-(3',5'-dinitrobenzamido)- 1-phenylethanol have been compared to those of the free compounds by 1H NMR investigations. Completely different interaction models, also involving changes of the free state conformations, have been obtained.
- Uccello-Barretta, Gloria,Balzano, Federica,Quintavalli, Cristiana,Salvadori, Piero
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- A Comparison of Ligands Proposed for the Asymmetric Dihydroxylation
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Comparative data for several ligands proposed recently for use in the osmium-catalyzed asymmetric dihydroxylation (AD) are presented.
- Crispino, Gerard A.,Makita, Atsushi,Wang, Zhi-Min,Sharpless, K. Barry
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- Predictive model for epoxide hydrolase-generated stereochemistry in the biosynthesis of nine-membered enediyne antitumor antibiotics
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Nine-membered enediyne antitumor antibiotics C-1027, neocarzinostatin (NCS), and kedarcidin (KED) possess enediyne cores to which activity-modulating peripheral moieties are attached via (R)- or (S)-vicinal diols. We have previously shown that this stereochemical difference arises from hydrolysis of epoxide precursors by epoxide hydrolases (EHs) with different regioselectivities. The inverting EHs, such as SgcF, hydrolyze an (S)-epoxide substrate to yield an (R)-diol in C-1027 biosynthesis, whereas the retaining EHs, such as NcsF2 and KedF, hydrolyze an (S)-epoxide substrate to yield an (S)-diol in NCS and KED biosynthesis. We now report the characterization of a series of EH mutants and provide a predictive model for EH regioselectivity in the biosynthesis of the nine-membered enediyne antitumor antibiotics. A W236Y mutation in SgcF increased the retaining activity toward (S)-styrene oxide by 3-fold, and a W236Y/Q237M double mutation in SgcF, mimicking NcsF2 and KedF, resulted in a 20-fold increase in the retaining activity. To test the predictive utility of these mutations, two putative enediyne biosynthesis-associated EHs were identified by genome mining and confirmed as inverting enzymes, SpoF from Salinospora tropica CNB-440 and SgrF (SGR-625) from Streptomyces griseus IFO 13350. Finally, phylogenetic analysis of EHs revealed a familial classification according to inverting versus retaining activity. Taken together, these results provide a predictive model for vicinal diol stereochemistry in enediyne biosynthesis and set the stage for further elucidating the origins of EH regioselectivity.
- Horsman, Geoffrey P.,Lechner, Anna,Ohnishi, Yasuo,Moore, Bradley S.,Shen, Ben
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- Stereochemistry of the Spontaneous, Acid-Catalyzed and Base Catalyzed Hydrolyses of Styrene Oxide
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The stereochemical courses of the spontaneous, hydronium ion-catalyzed and hydroxide ion-catalyzed hydrolyses of (R)-styrene oxide have been determined by 1H NMR analysis of the bis-(+)-α-(methoxy-α-trifluoromethyl)phenylacetate diesters of the styrene glycol products from each reaction.The glycol product from the spontaneous reaction of chiral styrene oxide is the result of 93percent inversion and 7percent retention.This result, coupled with published results of 18O-labeling experiments, indicates that essentially all of the styrene oxide that reacts with cleavage of the benzyl C-O bond yields glycol with inversion of stereochemistry at the benzyl carbon.A mechanism involving addition of neutral water concerted with benzyl C-O bond breaking is proposed for this reaction.The glycol product from the acid-catalyzed reaction was determined to be the result of 67percent inversion and 33percent retention at the benzyl carbon.This result, which agrees with one previous publication and contradicts that of another, reflects the stereochemistry of addition of solvent to the benzyl carbon.Consistent with a recent report that 18O-hydroxide attacks the α- and β-carbons of styrene oxide at almost equal rates, styrene glycol from the reaction of chiral styrene oxide with sodium hydroxide was found to be, within experimental error, completely racemic.
- Lin, Bin,Whalen, Dale L.
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- One-Pot Three-Step Consecutive Transformation of L-α-Amino Acids to (R)- and (S)-Vicinal 1,2-Diols via Combined Chemical and Biocatalytic Process
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Optically pure vicinal 1,2-diols are versatile chiral building blocks in the fine chemical and pharmaceutical industries. L-α-amino acid is a good feedstock source for high value-added product production since it is inexpensive and renewable. However, conversion of L-α-amino acids to enantioenriched vicinal 1,2-diols remains a significant challenge. In this study, combining a simple chemical process and a three-enzyme cascade biocatalysis system, we have successfully implemented a one-pot sequential process for the transformation of L-α-amino acids into enantiopure vicinal 1,2-diols in aqueous medium. Firstly, the NaBH4-H2SO4 system converted L-α-amino acids to (S)-amino alcohols via amino acid carboxyl reduction. Secondly, the three-enzyme (transaminase, carbonyl reductase and glucose dehydrogenase) cascade biocatalysis system converted amino alcohols to enantiopure vicinal 1,2-diols via amino alcohol deamination, α-hydroxy ketone asymmetric reduction and cofactor regeneration. Taking advantage of the two different reaction systems, chiral vicinal 1,2-diols could be obtained from L-α-amino acids with high yields (69–90 %) and excellent ee values (91–>99 % ee).
- Zhang, Jian-Dong,Zhao, Jian-Wei,Gao, Li-Li,Zhao, Jing,Chang, Hong-Hong,Wei, Wen-Long
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- Highly enantioselective conversion of racemic 1-phenyl-1,2-ethanediol by stereoinversion involving a novel cofactor-dependent oxidoreduction system of Candida parapsilosis CCTCC M203011
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An economical and convenient biocatalytic process was developed for the preparation of (S)-1-phenyl-1,2-ethanediol (PED), which is a valuable chiral building block for pharmaceuticals and liquid crystals, by stereoselective microbial conversion from the corresponding racemate. As a result of screening bacteria, yeasts, and molds, the enantioselective conversion of racemic PED by Candida parapsilosis CCTCC M203011 was found to be the most efficient process to produce (S)-PED with high optical purity of 98% ee and yield of 92%. By detecting the intermediate produced in the reaction by GC-MS, it was suggested that (S)-enantiomer was produced from the intermediate identified as β-hydroxyacetophenone by asymmetric reduction after stereoselective oxidation of (R)-enantiomer to β-hydroxyacetophenone. After investigating the cofactor requirement and stereospecificity of the reaction catalyzed by the cell-free extract from C. parapsilosis CCTCC M203011, it was found that the stereoselective conversion involved the oxidation of (R)-PED to the intermediate with NADP+ as the cofactor and the reduction reaction that formed the product used NADH as the cofactor, which was catalyzed by a novel cofactor-dependent oxidoreduction system. The NADP+-dependent (R)-specific alcohol dehydrogenase involved in stereoinversion was purified from C. parapsilosis CCTCC M203011, which has a relative molecular mass of 45kD.
- Nie, Yao,Xu, Yan,Mu, Xiao Qing
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- Activation and deactivation of Cp*Ir(TsDPEN) hydrogenation catalysts in water
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The addition of H3PO4 to Cp*Ir(TsDPEN-H), where TsDPEN = H2NCHPhCHPhNTs, is a simple method to obtain a water-soluble hydrogenation catalyst capable of reducing aromatic ketones to their corresponding alcohols in aqueous solutions. Key to the reactivity is the low affinity of the coordinatively unsaturated [Cp*Ir(TsDPEN)]+ for H2PO4. Catalyst degradation proceeds via the protonation of the tosylamido ligand, as was established by the crystallographic characterization of the tosylamine complex [Cp*Ir(NCMe)(HTsDPEN)] 2+.
- Letko, Christopher S.,Heiden, Zachariah M.,Rauchfuss, Thomas B.
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- Rhodium catalysed enantioselective hydroboration of alkenylboronic esters with catecholborane
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Alkenylboronic esters such as (E)-2-(2-phenylethenyl)-1,3,2-dioxaborolane were subjected to catalytic hydroboration with catecholborane and with use of neutral and cationic rhodium complexes modified by various diphosphine ligands. The resulting 1,2-diboryl intermediate was oxidised with alkaline hydrogen peroxide to give the corresponding 1,2-diol with enantioselectivities up to 79% e.e.
- Wiesauer, Christian,Weissensteiner, Walter
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- Coupled (R)-carbonyl reductase and glucose dehydrogenase catalyzes (R)-1-phenyl-1,2-ethanediol biosynthesis with excellent stereochemical selectivity
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The biotransformation of 2-hydroxyacetophenone to (R)-1-phenyl-1, 2-ethanediol (PED) by NADH-dependent (R)-carbonyl reductase (RCR) from Candida parapsilosis is slow and gives low yields, probably as a result of insufficient cofactors. To improve the biotransformation efficiency of (R)-PED from 2-hydroxyacetophenon, an enzyme-coupling system containing RCR and glucose dehydrogenase (GDH) was constructed to strengthen NADH-recycling pathway in Escherichia coli, in which the Shine-Dalgarno sequence and the aligned spacing sequence were used as linkers between them. The introduction of glucose dehydrogenase had little affects on the cell-growth. The co-expression conditions of RCR and glucose dehydrogenase was optimized to rebalance their catalytic functions. The ratio of kcat/KM for enzyme-coupling system catalyzing 2-HAP and glucose was about 1.0, suggesting the good balance between the functions of RCR and GDH. The rebalanced system gave excellent performance in (R)-PED biotransformation: an optical purity of 99.9% and a yield of 99.9% at optimal conditions: 35°C and pH 7.0. The introduction of glucose dehydrogenase stimulated increases of 23.8% and 63.8%, in optical purity and yield of (R)-PED, and simultaneously reduced the reaction time two-fold. This work provided a valuable method for efficient chiral alcohol production through protein-expression and biotransformation optimization to rebalance cofactor pathways.
- Zhou, Xiaotian,Zhang, Rongzhen,Xu, Yan,Liang, Hongbo,Jiang, Jiawei,Xiao, Rong
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- Asymmetric dihydroxylation with silica-anchored alkaloids
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Diols with excellent enantiomeric excesses are obtained from unfunctionalised alkenes in high yields by osmium-catalysed dihydroxylationsusingsilica-boundpyrimidineandpyrazino-pyridazine ligands.
- Bolm, Carsten,Maischak, Astrid,Gerlach, Arne
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- Lewis pairs for ring-opening alternating copolymerization of cyclic anhydrides and epoxides
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A simple and highly active catalytic process for ring-opening alternating copolymerization (ROAC) of cyclic anhydrides and epoxides still remains a key challenge. Herein, we have described an effective group of versatile and low-toxic zinc dicarbyl/amine Lewis pairs for the ROAC. The facile route showed a high catalytic activity (TOF ≤ 210 h-1 at 110 °C) and perfectly alternating selectivity (>99%). An unexpected highly regioselective ring-opening of asymmetric epoxides (PO, ECH and SO) was also achieved by the combination of zinc alkyls (or aryls) and amines. Of note, deprotonation side reaction of α-H of anhydrides with organic bases was uncovered, and subsequently was inhibited by using nonpolar solvents and Lewis acid/base pairs. Thus, an array of polyesters was synthesized by the coupling of various anhydrides (PA, CHA, SA and NA) and epoxides (CHO, PO, ECH and SO) using the same Lewis pairs. Furthermore, variable temperature 1H NMR spectral and MALDI TOF MS analyses were performed to understand the possible mechanism and microstructure. The experimental results indicated that zwitterionic alkoxide and carboxylate intermediates alternately formed to enhance the ester repeat units in chain initiation and propagation. This work provides a simple and green catalytic strategy to prepare diversified polyesters from the ROAC process of cyclic anhydrides and epoxides with considerable catalytic activity and alternating selectivity.
- Ji, He-Yuan,Wang, Bin,Pan, Li,Li, Yue-Sheng
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- Enantioselective hydrolysis of styrene oxide with the epoxide hydrolase of Sphingomonas sp. HXN-200
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The soluble bacterial epoxide hydrolase (EH) from Sphingomonas sp. HXN-200 catalyzed the enantioselective hydrolysis of racemic styrene oxide to give (S)-styrene oxide with an enantiomeric ratio (E) of 21-23 in aqueous buffer, better than any reported native EHs. The ring opening of the styrene oxide with this EH was only at the terminal position for the (S)-enantiomer and at the terminal and benzylic position in an 87:13 ratio for the (R)-enantiomer. Enzymatic hydrolysis of the styrene oxide in a two-liquid phase system significantly reduced autohydrolysis, thus improving the E to 26-29. Hydrolysis of 160 mM styrene oxide with cell-free extract (CFE) of Sphingomonas sp. HXN-200 (10 mg protein/mL) in aqueous buffer and n-hexane (1:1) for 30.7 h afforded 39.2% (62.7 mM) of (S)-styrene oxide in >99.9% ee. The lyophilized CFE was proven to be stable, while the rehydrated lyophilized CFE powder was successfully used for the hydrolysis of 320 mM styrene oxide in the two-liquid phase system, yielding 40.2% (128.6 mM) of (S)-styrene oxide in >99.9% ee after 13.8 h. No inhibitory effect of the diol product on the hydrolysis was observed when the diol concentration was lower than 476 mM, suggesting a straightforward process for the hydrolysis of up to 1 M styrene oxide.
- Liu, Zeya,Michel, Johannes,Wang, Zunsheng,Witholt, Bernard,Li, Zhi
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- Highly efficient and recyclable chiral Pt nanoparticle catalyst for enantioselective hydrogenation of activated ketones
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Thermoregulated phase-separable chiral Pt nanoparticle catalyst exhibited excellent ee (>99%) in the enantioselective hydrogenation of activated ketones for preparing chiral α-hydroxy acetals and chiral 1,2-diols. More importantly, the chiral catalyst could be easily separated by phase separation and directly reused in the next cycle without any loss in catalytic activity and enantioselectivity, even in the gram-scale reaction. The leaching of Pt was under the detection limit of the instrument.
- Xue, Xiuru,Chen, Pu,Xu, Peng,Wang, Yanhua
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- Using deep eutectic solvents to improve the biocatalytic reduction of 2-hydroxyacetophenone to (R)-1-phenyl-1,2-ethanediol by Kurthia gibsonii SC0312
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The effects of five deep eutectic solvents (DESs) on the production of (R)-1-phenyl-1,2-ethanediol from 2-hydroxyacetophenone catalyzed by Kurthia gibsonii SC0312 were investigated in this study. Of these, choline chloride/1,4-butanediol (ChCl/Bd) showed excellent biocompatibility and suitably increased the cell membrane permeability while having a little impact on the structure of DNA. Indeed, ChCl/Bd at the concentration of 2 % increased the catalytic rate of the cells by 22 %. The other DESs did not stimulate the catalytic capacity of the cells, despite some increases in the cell membrane permeability. Additionally, the conformation of DNA was visibly changed when adding the other examined DESs except for choline chloride/triethylene glycol. The DESs modified the fatty acid composition of cellular membrane, decreased the relative amount of iso-C14:0 and increased the relative amount of normal C15:0. Meanwhile, the DESs were able to improve the relative ratio of normal fatty acids to branched fatty acids. Finally, a highly efficient reduction of 80 mM 2-hydroxyacetophenone by K. gibsonii SC0312 in the ChCl/Bd-containing system was established, affording (R)-1-phenyl-1,2-ethanediol in 80 % yield and optical purity >99 % at 30 mg/mL wet cells. This work offers a promising approach for the preparation of (R)-1-phenyl-1,2-ethanediol from 2-hydroxyacetophenone using K. gibsonii SC0312.
- Peng, Fei,Chen, Qing-Sheng,Li, Fang-Zhou,Ou, Xiao-Yang,Zong, Min-Hua,Lou, Wen-Yong
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- De novo construction of multi-enzyme system for one-pot deracemization of (R,S)-1-phenyl-1,2-ethanediol by stereoinversion of (S)-enantiomer to the corresponding counterpart
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Deracemization via oxidoreductive stereoinversion is one of the most attractive methods for the preparation of enantiomerically pure compounds. However, available enzymatic system is yet limited for efficiently catalyzing deracemization to produce optically pure alcohol in certain configuration. Through evaluation of available stereoselective oxidoreductases on activity, selectivity, and cofactor dependency, the suitable candidates were obtained to construct the enzymatic deracemization system involving cofactor self-recycling. For deracemizing (R,S)-1-phenyl-1,2-ethanediol (PED) to (R)-PED, a facile one-pot system was established by combination of two stereoselective oxidoreductases, the stereospecific carbonyl reductase 1 (SCR1) and the ketoreductase (KRD). To rebalance the activities and catalytic functions of different enzymes involved in the multi-enzyme system, the reaction conditions of SCR1-catalyzed oxidation and KRD-mediated reduction were optimized, respectively. Consequently, the deracemization system involving cofactor self-recycling was built to produce (R)-PED with the optical purity of 95.50%e.e. and the yield of 91.62% from the corresponding racemate (1 g L-1), under the optimal reaction conditions including activity ratio of SCR1/KRD 1:4 (SCR1 10 U mL-1 and KRD 40 U mL-1), molar ratio of NADP+/NADPH 3:1, 30°C, and pH 7.0. Therefore, the developed strategy would be useful to construct the multi-enzyme deracemization system based on systematic evaluation of enzyme features.
- Li, Bin,Nie, Yao,Mu, Xiao Qing,Xu, Yan
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- Stereoselective 1,2-additions of α-alkoxymethyllithiums to aldehydes
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(equation presented) A chiral derivative of tributylstannymethanol, readily prepared from L-valine, undergoes Sn-Li exhange to provide an α-alkoxyorganolithium that adds to aldehydes with up to 91:9 dr. The diastereoselectivity depends on the solvent and alkyllithium used for transmetalation. Treatment of adducts with acid allowed recovery of the chiral auxiliary and diol with complete stereochemical integrity.
- Smyj, Robert P.,Chong, J. Michael
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- New kinetic and thermodynamic approach of one-pot synthesis of chiral alcohol by oxidoreductase from Candida parapsilosis
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The stereoinversion process involving two sequential stereoselective oxidation and reduction reactions by oxidoreductases was a typical and important one-pot method for chiral secondary alcohol synthesis which has great potential for industrial application. The process to produce (S)-1-phenyl-1,2-ethanediol with whole cell was chosen as a model reaction to investigate the kinetic and thermodynamic properties of key enzymes which catalyzed the single oxidation and reduction step of the whole reaction. The kinetic data from initial rate experiments in the absence of product prove that both oxidation and reduction reactions follow Theorell-Chance BiBi mechanism. Parameters of Vm and ΔS suggest that the oxidation reaction was thermodynamically unfavorable and the restrictive step of the one-pot process was inhibited at high concentration of substrate PED. To remove the inhibition of substrate, extractive biocatalytic methods were successfully applied to improve the substrate PED concentration from 15 g/l to 50 g/l with high optical purity of 91.6% and yield of 82.5%.
- Mu, Xiao Qing,Xu, Yan,Yang, Ming,Sun, Zhi Hao
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- Resolution of 1,2-diols by enzyme-catalyzed oxidation with anodic, mediated cofactor regeneration in the extractive membrane reactor: Gaining insight by adaptive simulation
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Oxidative racemic resolution of 1,2-diols is a method for the synthesis of enantiopure diols not easily accessed by reduction. The constraints generally found for oxidation to hydroxy ketones can be overcome by coupling various techniques. To circumvent product inhibition, a membrane reactor with solvent extraction of the lipophilic product was chosen. For the oxidative regeneration of NAD+ from NADH anodic oxidation mediated by ABTS was used. The kinetic characteristics of the system were determined independently for each significant system step. However, it proved difficult to simulate the coupled process completely with the kinetic data obtained independently, as true reaction conditions are not covered by kinetic experiments. A mixed approach using a system of ordinary differential equations corrected with data from the process (e.g. enzyme activity) leads to a satisfactory description. This model was applied as a starting point for identifying the relevant process parameters.
- Degenring, Daniela,Schroeder, Iris,Wandrey, Christian,Liese, Andreas,Greiner, Lasse
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- Efficient bioreduction of 2-hydroxyacetophenone to (S)-1-phenyl-1, 2-ethanediol through homologous expression of (S)-carbonyl reductase II in Candida parapsilosis CCTCC M203011
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(S)-carbonyl reductase II (SCRII), a short-chain alcohol dehydrogenase from Candida parapsilosis M203011, catalyzes the bioreduction of 2-hydroxyacetophenone (2-HAP) to (S)-1-phenyl-1,2-ethanediol ((S)-PED). When SCRII was expressed in Escherichia coli, the biotransformation efficiency of (S)-PED was low. To improve its biocatalytic efficiency, the homologous expression of SCRII in C. parapsilosis M203011 was attempted. The scrII gene was cloned into an expression vector pCP carrying MAL2 as its promoter and SAT1 as its selection marker. Data obtained in this study showed that SCRII was successfully expressed in recombinant strain C. parapsilosis/pCP-scrII. The reductive activity toward 2-HAP exhibited about 2-fold and 6-fold increase in the cell-free extracts of C. parapsilosis/pCP-scrII than those of the wild-type and E. coli/pET28-SCRII. Under the optimal bioreaction conditions (pH 5.5, 35?°C), the optical purity and yield of (S)-PED were both over 99.9% produced by C. parapsilosis/pCP-scrII. Additionally, 500-mL preparative scale bioreduction with efficient whole-cell process was performed, and the optical purity was over 99.9% with an isolated yield of about 70%. Our work not only demonstrated the high catalytic efficiency given by the homologous expression of SCRII in C. parapsilosis, but also provides an economical method for the preparation of optically pure chiral alcohols with whole-cell process.
- Li, Yaohui,Zhang, Rongzhen,Xu, Yan,Xiao, Rong,Wang, Lei,Zhou, Xiaotian,Liang, Hongbo,Jiang, Jiawei
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- Directed Evolution of Alcohol Dehydrogenase for Improved Stereoselective Redox Transformations of 1-Phenylethane-1,2-diol and Its Corresponding Acyloin
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Laboratory evolution of alcohol dehydrogenase produced enzyme variants with improved turnover numbers with a vicinal 1,2-diol and its corresponding hydroxyketone. Crystal structure and transient kinetics analysis aids in rationalizing the new functions of these variants.
- Hamnevik, Emil,Maurer, Dirk,Enugala, Thilak Reddy,Chu, Thao,L?fgren, Robin,Dobritzsch, Doreen,Widersten, Mikael
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- Osmium Tetroxide Anchored to Porous Resins Bearing Residual Vinyl Groups: A Highly Active and Recyclable Solid for Asymmetric Dihydroxylation of Olefins
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(Matrix Presented) OsO4 was simply immobilized onto resins such as Amberlite XAD-4 or XAD-7 bearing residual vinyl groups. The resulting osmylated resins are air-stable, nonvolatile, and much easier to handle than their homogeneous counterpart (OsO4). Moreover, the resin-bound OsO4 exhibited excellent catalytic activity in the asymmetric dihydroxylation of olefins and was easily recovered and reused in five consecutive reactions without any significant decrease in product yield. Turnover time, however, was significantly increased for the fourth and fifth reactions.
- Yang, Jung Woons,Han, Hogyu,Roh, Eun Joo,Lee, Sang-Gi,Song, Choong Eui
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- Method for synthesizing chiral 1,2-diol compound
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The invention relates to a method for synthesizing a chiral 1,2-diol compound, which comprises the following steps: sequentially adding a cobalt catalyst, a ligand, alpha-hydroxy ketone, an organic solvent and silane into a reaction system at 20-30 DEG C in a nitrogen atmosphere, then stirring the mixture, and carrying out column chromatography separation on the obtained product to obtain the chiral 1,2-diol compound. The high-yield cobalt catalyst in the earth crust is used, meanwhile, cheap silane (PMHS, 500 g/298 yuan) is used as a reducing agent, the asymmetric reduction reaction of alpha-hydroxy ketone can be efficiently achieved under the mild condition, and the chiral 1,2-diol compound with high yield and optical activity is obtained. Moreover, through the creative labor of the inventor, the reaction yield can reach 99%, and meanwhile, the content of the target product in the generated reaction product is 99% (namely, the yield is 99%, 99% ee).
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Paragraph 0027; 0029-0032; 0085-0093
(2021/07/21)
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- Tridentate nitrogen phosphine ligand containing arylamine NH as well as preparation method and application thereof
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The invention discloses a tridentate nitrogen phosphine ligand containing arylamine NH as well as a preparation method and application thereof, and belongs to the technical field of organic synthesis. The tridentate nitrogen phosphine ligand disclosed by the invention is the first case of tridentate nitrogen phosphine ligand containing not only a quinoline amine structure but also chiral ferrocene at present, a noble metal complex of the type of ligand shows good selectivity and extremely high catalytic activity in an asymmetric hydrogenation reaction, meanwhile, a cheap metal complex of the ligand can also show good selectivity and catalytic activity in the asymmetric hydrogenation reaction, and is very easy to modify in the aspects of electronic effect and space structure, so that the ligand has huge potential application value. A catalyst formed by the ligand and a transition metal complex can be used for catalyzing various reactions, can be used for synthesizing various drugs, and has important industrial application value.
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Paragraph 0117-0120
(2021/06/26)
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- Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade
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Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols via enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant. Coupled with azide as a nucleophile for regioselective ring opening, this chemo-enzymatic cascade produced highly enantioenriched aromatic α-azido alcohols with up to >99% conversion. A bi-enzymatic counterpart with halohydrin dehalogenase-catalyzed azidolysis afforded the alternative β-azido alcohol isomers with up to 94% diastereomeric excess. We anticipate our biocatalytic cascade to be a starting point for more practical production of these chiral compounds with two-component flavoprotein monooxygenases.
- Franssen, Maurice C. R.,Hollmann, Frank,Martínez-Montero, Lía,Paul, Caroline E.,Süss, Philipp,Schallmey, Anett,Tischler, Dirk
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p. 5077 - 5085
(2021/08/16)
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- Enantiocomplementary C–H Bond Hydroxylation Combining Photo-Catalysis and Whole-Cell Biocatalysis in a One-Pot Cascade Process
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Enantiocomplementary hydroxylation of alkyl aromatics through a one-pot photo-biocatalytic cascade reaction is described. The photoredox process is implemented in aqueous phase with O2 as oxidant and the subsequent (R)- or (S)-selective bioreduction is performed by whole cell system without the addition of the expensive cofactor (NADPH). This mild, operationally simple protocol transforms a wide variety of readily available aromatic compounds into valuable chiral alcohols with high yield (up to 90 %) and stereoselectivity (up to 99 %), thereby displaying important potentials in organic synthesis.
- Peng, Yongzhen,Li, Danyang,Fan, Jiajie,Xu, Weihua,Xu, Jian,Yu, Huilei,Lin, Xianfu,Wu, Qi
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supporting information
p. 821 - 825
(2020/02/20)
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- Application of the redox system of Nocardia corallina B-276 in the enantioselective biotransformation of ketones and alcohols
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The aim of this research was to evaluate the redox system of Nocardia corallina B-276 in the biotransformation of 1-phenyl-1-propanone (1a), 2-hydroxy-1-phenylethanone (2a) and methyl (2-chlorophenyl)(oxo)acetate (3a) into 1-phenylpropan-1-ol (1b), 1-phenyl-1,2-ethanediol (2b) and methyl (2-chlorophenyl)(hydroxy)acetate (3b). The biomass of N. corallina was obtained in a liquid medium with an initial pH of 8.50, but the pH changed during the 96 h of the culture media, the final pH was between 4.74 and 7.62. The N. corallina biomass biocatalyzed the enantioselective reduction of 1a–3a to the corresponding alcohols. Whereas, during the process of oxidation of the rac-alcohols 1b–3b, 1b was oxidized in enantioselective way, the oxidation of 2b was not selective, but 3b was biotransformed mainly to (R)-3b. These results are indicative that N. corallina produced reductases and oxidases, whereby the biocatalytic activity was influenced by the final pH of the culture media, the reaction time and structure of the substrate.
- Alvarez, Norberto Manjarrez,Pérez Méndez, Herminia I.,Oba, Aida Solís,Cabello, Lucía Ortega,Lara Carvajal, María T.,Valencia Ledezma, Omar E.,Martínez-Casares, Rubria M.
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p. 279 - 290
(2020/06/01)
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- Highly regio- and enantio-selective hydrolysis of two racemic epoxides by GmEH3, a novel epoxide hydrolase from Glycine max
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A novel epoxide hydrolase from Glycine max, designated GmEH3, was excavated based on the computer-aided analysis. Then, gmeh3, a GmEH3-encoding gene, was cloned and successfully expressed in E. coli Rosetta(DE3). Among the ten investigated rac-epoxides, GmEH3 possessed the highest and best complementary regioselectivities (regioselectivity coefficients, αS = 93.7% and βR = 97.2%) in the asymmetric hydrolysis of rac-m-chlorostyrene oxide (5a), and the highest enantioselectivity (enantiomeric ratio, E = 55.6) towards rac-phenyl glycidyl ether (7a). The catalytic efficiency (kcatS/KmS = 2.50 mM?1 s?1) of purified GmEH3 for (S)-5a was slightly higher than that (kcatR/KmR = 1.52 mM?1 s?1) for (R)-5a, whereas the kcat/Km (5.16 mM?1 s?1) for (S)-7a was much higher than that (0.09 mM?1 s?1) for (R)-7a. Using 200 mg/mL wet cells of E. coli/gmeh3 as the biocatalyst, the scale-up enantioconvergent hydrolysis of 150 mM rac-5a at 25 °C for 1.5 h afforded (R)-5b with 90.2% eep and 95.4% yieldp, while the kinetic resolution of 500 mM rac-7a for 2.5 h retained (R)-7a with over 99% ees and 43.2% yields. Furthermore, the sources of high regiocomplementarity of GmEH3 for (S)- and (R)-5a as well as high enantioselectivity towards rac-7a were analyzed via molecular docking (MD) simulation.
- Zhang, Chen,Li, Chuang,Zhu, Xiu-xiu,Liu, You-yi,Zhao, Jun,Wu, Min-chen
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p. 2795 - 2803
(2020/09/01)
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- Reprogramming Epoxide Hydrolase to Improve Enantioconvergence in Hydrolysis of Styrene Oxide Scaffolds
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Enantioconvergent hydrolysis by epoxide hydrolase is a promising method for the synthesis of important vicinal diols. However, the poor regioselectivity of the naturally occurring enzymes results in low enantioconvergence in the enzymatic hydrolysis of styrene oxides. Herein, modulated residue No. 263 was redesigned based on structural information and a smart variant library was constructed by site-directed modification using an “optimized amino acid alphabet” to improve the regioselectivity of epoxide hydrolase from Vigna radiata (VrEH2). The regioselectivity coefficient (r) of variant M263Q for the R-isomer of meta-substituted styrene oxides was improved 40–63-fold, and variant M263V also exhibited higher regioselectivity towards the R-isomer of para-substituted styrene oxides compared with the wild type, which resulted in improved enantioconvergence in hydrolysis of styrene oxide scaffolds. Structural insight showed the crucial role of residue No. 263 in modulating the substrate binding conformation by altering the binding surroundings. Furthermore, increased differences in the attacking distance between nucleophilic residue Asp101 and the two carbon atoms of the epoxide ring provided evidence for improved regioselectivity. Several high-value vicinal diols were readily synthesized (>88% yield, 90%–98% ee) by enantioconvergent hydrolysis using the reprogrammed variants. These findings provide a successful strategy for enhancing the enantioconvergence of native epoxide hydrolases through key single-site mutation and more powerful enzyme tools for the enantioconvergent hydrolysis of styrene oxide scaffolds into single (R)-enantiomers of chiral vicinal diols. (Figure presented.).
- Li, Fu-Long,Qiu, Yan-Yan,Zheng, Yu-Cong,Chen, Fei-Fei,Kong, Xu–Dong,Xu, Jian-He,Yu, Hui-Lei
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p. 4699 - 4706
(2020/09/21)
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- Manipulating regioselectivity of an epoxide hydrolase for single enzymatic synthesis of (: R)-1,2-diols from racemic epoxides
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Both the activity and regioselectivity of Phaseolus vulgaris epoxide hydrolase were remarkably improved via reshaping two substrate tunnels based on rational design. The elegant one-step enantioconvergent hydrolysis of seven rac-epoxides was achieved by single mutants, allowing green and efficient access to valuable (R)-1,2 diols with high eep (90.1-98.3%) and yields.
- Hu, Die,Zong, Xun-Cheng,Xue, Feng,Li, Chuang,Hu, Bo-Chun,Wu, Min-Chen
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supporting information
p. 2799 - 2802
(2020/03/13)
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- An easy and low-cost method of embedding chiral molecules in metal-organic frameworks for enantioseparation
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A facile method, post-synthetic exchange of modulators (PSEm), has been demonstrated here to prepare chiral metal-organic frameworks for enantioseparation. Based on this method, three chiral porous Zr-based metal-organic frameworks have been prepared through exchanging the coordinated modulators on metal clusters of MOFs with commercially available chiral carboxylic acid molecules. In addition, the obtained materials show enantioselectivity toward three different enantiomers, which presents a proof of concept for the design of MOF materials for enantioseparation by an easy and low-cost method. This journal is
- Cao, Rong,Fang, Zhi-Bin,Hu, Xiao-Jing,Huang, Ge,Liu, Tian-Fu,Zhang, Shuo
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supporting information
p. 7459 - 7462
(2020/07/15)
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- Engineering a homochiral metal-organic framework based on an amino acid for enantioselective separation
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A chiral metal-organic framework possessing an open amphiphilic channel is constructed from a dicarboxylate ligand derived from an amino acid and is shown to be an efficient and recyclable chiral solid adsorbent, which is capable of separating racemic secondary alcohols, epoxides, and ibuprofen with very high enantioselectivity.
- Tang, Haitong,Yang, Keke,Wang, Kun-Yu,Meng, Qi,Wu, Fan,Fang, Yu,Wu, Xiang,Li, Yougui,Zhang, WenCheng,Luo, Yunfei,Zhu, Chengfeng,Zhou, Hong-Cai
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p. 9016 - 9019
(2020/08/17)
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- Racemic or enantioselective osmium-catalyzed dihydroxylation of olefins under near-neutral conditions
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K3Fe(CN)6 and NaIO4 serve as catalytic co-oxidants for osmium-catalyzed dihydroxylations that are performed under near-neutral conditions with K2S2O8 as the stoichiometric oxidant and Na2HPO4 as the base. By using either quinuclidine or hydroquinidine 1,4-phthalazinediyl ether [(DHQD)2Phal], good yields of racemic or enantioenriched diols are obtained. This simple, biphasic procedure offers advantages over other neutral dihydroxylation protocols that use N-methylmorpholine oxide as the stoichiometric oxidant, by suppressing the secondary catalytic cycle that leads to reduced enantioselectivities. The utility of the procedure, which is nicely suited for base-labile starting materials or products, is demonstrated by performing the dihydroxylation in the presence of an aliphatic aldehyde moiety.
- Blumberg, Shawn,Martin, Stephen F.
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- Cleavage of N-H Bond of Ammonia via Metal-Ligand Cooperation Enables Rational Design of a Conceptually New Noyori-Ikariya Catalyst
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The asymmetric transfer hydrogenation (ATH) of ketones/imines with Noyori-Ikariya catalyst represents an important reaction in both academia and fine chemical industry. The method allows for the preparation of chiral secondary alcohols/amines with very good to excellent optical purities. Remarkably, the same chiral Noyori-Ikariya complex is also a precatalyst for a wide range of other chemo- and stereoselective reductive and oxidative transformations. Among them are enantioselective sulfonamidation of acrylates (intramolecular aza-Michael reaction) and carboxylation of indoles with CO2. Development of these catalytic reactions has been inspired by the realized cleavage of the N-H bond of sulfonamides and indoles by the 16e- amido derivative of the 18e- precatalyst via metal-ligand cooperation (MLC). This paper summarizes our efforts to investigate N-H bond cleavage of gaseous ammonia in solution via MLC and reports the serendipitous discovery of a new class of chiral tridentate I3[N,N′,N″] Ru and Ir metallacycles, derivatives of the famous M-FsDPEN catalysts (M = Ru, Ir). The protonation of these metallacycles by strong acids containing weakly coordinating (chiral) anions generates ionic complexes, which were identified as conceptually novel Noyori-Ikariya precatalysts. For example, the ATH of aromatic ketones with some of these complexes proceeds with up to 99% ee.
- Dub, Pavel A.,Matsunami, Asuka,Kuwata, Shigeki,Kayaki, Yoshihito
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p. 2661 - 2677
(2019/02/14)
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- Enantioselective Resolution Copolymerization of Racemic Epoxides and Anhydrides: Efficient Approach for Stereoregular Polyesters and Chiral Epoxides
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Herein we report an efficient strategy for preparing isotactic polyesters and chiral epoxides via enantioselective resolution copolymerization of racemic terminal epoxides with anhydrides, mediated by enantiopure bimetallic complexes in conjunction with a nucleophilic cocatalyst. The chirality of both the axial linker and the diamine backbones of the ligand are responsible for the chiral induction of this kinetic resolution copolymerization process. The catalyst systems exhibit exceptional levels of enantioselectivity with a kinetic resolution coefficient exceeding 300 for various racemic epoxides, affording highly isotactic copolymers (selectivity factors of more than 300) with a completely alternating structure and low polydispersity index. Most of the produced isotactic polyesters are typical semicrystalline materials with melting temperatures in the range from 77 to 160 °C.
- Li, Jie,Ren, Bai-Hao,Wan, Zhao-Qian,Chen, Shi-Yu,Liu, Ye,Ren, Wei-Min,Lu, Xiao-Bing
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supporting information
p. 8937 - 8942
(2019/06/11)
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- Highly regio- And stereoselective synthesis of cyclic carbonates from biomass-derived polyols: Via organocatalytic cascade reaction
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The cascade reaction of CO2, vicinal diols, and propargylic alcohol, was firstly achieved by dual Lewis base (LB) organocatalytic systems involving LB-CO2 adducts and commercially available organic amines. This methodology could overcome the chemical inertness of CO2, providing an alternative route to various functionalized five-membered cyclic carbonates in moderate to high yields under mild reaction conditions (25 °C, 1.0 atm of CO2). More importantly, this method could also be applied for facile and efficient synthesis of chiral polycyclic carbonates from biomass-derived polyols with complete configuration retention of chiral centers. This study provides an environment-friendly, scalable and cost effective protocol to construct value-added cyclic carbonates with multi-functional groups and chiral centers.
- Zhou, Hui,Zhang, Hui,Mu, Sen,Zhang, Wen-Zhen,Ren, Wei-Min,Lu, Xiao-Bing
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supporting information
p. 6335 - 6341
(2019/12/03)
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- Syn-dihydroxylation of alkenes using a sterically demanding cyclic diacyl peroxide
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The syn-dihydroxylation of alkenes is a highly valuable reaction in organic synthesis. Cyclic acyl peroxides (CAPs) have emerged recently as promising candidates to replace the commonly employed toxic metals for this purpose. Here, we demonstrate that the structurally demanding cyclic peroxide spiro[bicyclo[2.2.1]heptane-2,4′-[1,2]dioxolane]-3′,5′-dione (P4) can be effectively used for the syn-dihydroxylation of alkenes. Reagent P4 also shows an improved selectivity for dihydroxylation of alkenes bearing β-hydrogens as compared to other CAPs, where both diol and allyl alcohol products compete with each other. Furthermore, the use of enantiopure P4 (labeled P4′) demonstrates the potential of P4′ for a metal-free asymmetric syn-dihydroxylation of alkenes.
- Pilevar, Afsaneh,Hosseini, Abolfazl,Becker, Jonathan,Schreiner, Peter R.
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p. 12377 - 12386
(2019/10/11)
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- Structurally Defined α-Tetralol-Based Chiral Hypervalent Iodine Reagents
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A novel class of chiral hypervalent iodine reagents containing an α-tetralol scaffold is introduced. Iodine triacetate is employed in a key step as a highly selective and efficient iodinating reagent for a short and convenient synthesis of iodine(III) derivatives. Solid-state X-ray analyses offer valuable structural information, while reactivities and stereoselectivities are investigated in three model reactions.
- Hokamp, Tobias,Wirth, Thomas
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p. 8674 - 8682
(2019/07/03)
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- Exploiting Designed Oxidase-Peroxygenase Mutual Benefit System for Asymmetric Cascade Reactions
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A unique P450 monooxygenase-peroxygenase mutual benefit system was designed as the core element in the construction of a biocatalytic cascade reaction sequence leading from 3-phenyl propionic acid to (R)-phenyl glycol. In this system, P450 monooxygenase (P450-BM3) and P450 peroxygenase (OleTJE) not only function as catalysts for the crucial initial reactions, they also ensure an internal in situ H2O2 recycle mechanism that avoids its accumulation and thus prevents possible toxic effects. By directed evolution of P450-BM3 as the catalyst in the enantioselective epoxidation of the styrene-intermediate, formed from 3-phenyl propionic acid, and the epoxide hydrolase ANEH for final hydrolytic ring opening, (R)-phenyl glycol and 9 derivatives thereof were synthesized from the respective carboxylic acids in one-pot processes with high enantioselectivity.
- Yu, Da,Wang, Jian-Bo,Reetz, Manfred T.
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- Exploiting Designed Oxidase-Peroxygenase Mutual Benefit System for Asymmetric Cascade Reactions
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A unique P450 monooxygenase-peroxygenase mutual benefit system was designed as the core element in the construction of a biocatalytic cascade reaction sequence leading from 3-phenyl propionic acid to (R)-phenyl glycol. In this system, P450 monooxygenase (P450-BM3) and P450 peroxygenase (OleTJE) not only function as catalysts for the crucial initial reactions, they also ensure an internal in situ H2O2 recycle mechanism that avoids its accumulation and thus prevents possible toxic effects. By directed evolution of P450-BM3 as the catalyst in the enantioselective epoxidation of the styrene-intermediate, formed from 3-phenyl propionic acid, and the epoxide hydrolase ANEH for final hydrolytic ring opening, (R)-phenyl glycol and 9 derivatives thereof were synthesized from the respective carboxylic acids in one-pot processes with high enantioselectivity.
- Yu, Da,Wang, Jian-Bo,Reetz, Manfred T.
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p. 5655 - 5658
(2019/04/17)
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- Well-confined polyoxometalate-ionic liquid in silicic framework for environmentally friendly asymmetric di-hydroxylation of olefins
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Chiral 1,2-diols with a high yield could be directly prepared from asymmetric di-hydroxylation of olefins via an eco-friendly and enduring catalyst, in which abundant "chiral pools" of polyoxometalate-ionic liquid were target-designed into the silicic framework (POM-ILS) and well stabilized in aqueous media.
- Liang, Dong,Wang, Yan,Wang, Sifan,Song, Chengkun,Shi, Yonghe,Liu, Qinghao,Zhu, Hailin,Li, Xia,Liu, Laishuan,Zhu, Na
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p. 6102 - 6106
(2019/03/12)
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- Accessible Bifunctional Oxy-Tethered Ruthenium(II) Catalysts for Asymmetric Transfer Hydrogenation
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A concise synthesis of new oxy-tethered ruthenium complexes effective for the asymmetric transfer hydrogenation of aromatic ketones is described. The oxy-tether was constructed via a defluorinative etherification arising from an intramolecular nucleophilic substitution of a perfluorinated phenylsulfonyl substituent. The obtained tethered complexes exhibited desirable catalytic activity and selectivity, especially in the asymmetric transfer hydrogenation of functionalized aromatic ketones. The robustness and rigidity of the tether contribute to their superior catalytic performance relative to the nontethered prototype complex.
- Matsunami, Asuka,Ikeda, Marika,Nakamura, Hitomi,Yoshida, Minori,Kuwata, Shigeki,Kayaki, Yoshihito
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supporting information
p. 5213 - 5218
(2018/09/13)
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- Molecular Basis for the High Activity and Enantioselectivity of the Carbonyl Reductase from Sporobolomyces salmonicolor toward α-Haloacetophenones
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In an effort to develop a practical method for the synthesis of optically pure 2,2,2-trifluoro-1-phenylethanol, we found that the carbonyl reductase (SSCR) from Sporobolomyces salmonicolor showed excellent activity and enantioselectivity toward the halogenated acetophenones. Especially, SSCR exhibited more than 1000 times higher activity toward α,α,α-trifluoroacetophenone than unsubstituted acetophenone, a strikingly different observation from the previously well-studied alcohol dehydrogenase (LBADH) from Lactobacillus brevis. Enzyme-substrate docking and site-directed mutagenesis studies revealed the molecular basis for the high enzyme activity and enantioselectivity of SSCR toward the α-halogenated acetophenones. The hydrogen bond of the Asn207 side chain with the substrate halogen atom and the XH/π interaction of the substrate phenyl group with the side chains of Ser222/Thr223 resulted in the formation of the highly reactive conformation of α-halogenated acetophenones in the active site of the enzyme. (S)-2,2,2-Trifluoro-1-phenylethanol was prepared in excellent isolated yield and enantiomeric excess from the reduction of α,α,α-trifluoroacetophenone with mutant T209A. These results suggest that tuning the interactions between the halogen atoms/phenyl group of the substrate and the amino acid residues of the enzyme would lead to valuable mutants for the practical synthesis of β-haloalcohols.
- Chen, Xi,Zhang, Hongliu,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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p. 3525 - 3531
(2018/04/14)
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- Chiral Ion-Pair Organocatalyst-Promoted Efficient Enantio-selective Reduction of α-Hydroxy Ketones
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The enantioselective reduction of α-hydroxy ketones with catecholborane has been developed employing 5 mol% of an 1,1′-bi-2-naphthol (BINOL)-derived ion-pair organocatalyst. This methodology provides a straightforward access to the corresponding aromatic 1,2-diols in high yields (up to 90%) with excellent enantioselectivities (up to 97%). Furthermore, the α-amino ketones also could be reduced with moderate ee values under mild reaction condition. (Figure presented.).
- Zhang, Yiliang,He, Li,Shi, Lei
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p. 1926 - 1931
(2018/03/27)
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- Semirational Engineering of the Naphthalene Dioxygenase from Pseudomonas sp. NCIB 9816-4 towards Selective Asymmetric Dihydroxylation
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Enzyme-catalyzed asymmetric dihydroxylation is a powerful tool for the selective oxyfunctionalization of various organic compounds. By applying Rieske non-heme dioxygenases (ROs), molecular oxygen and a reduction equivalent are needed for the generation of vicinal cis-diols. We report a comprehensive mutagenesis study of the active site of the naphthalene dioxygenase from Pseudomonas sp. NCIB 9816-4 comprising 62 variants. We aimed to understand the important structure–function relationships by investigating different substituted arene substrates and the geometry of the active site. Introducing single-point mutations at positions F202, A206, V260, H295, F352, and L307 resulted in drastic shifts in the reaction specificity, regioselectivity, and stereoselectivity (≥90 %) while maintaining the residual activity towards the natural substrate naphthalene.
- Halder, Julia M.,Nestl, Bettina M.,Hauer, Bernhard
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p. 178 - 182
(2017/12/26)
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- Enantioselective Dihydroxylation of Alkenes Catalyzed by 1,4-Bis(9-O-dihydroquinidinyl)phthalazine-Modified Binaphthyl–Osmium Nanoparticles
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A series of unprecedented binaphthyl–osmium nanoparticles (OsNPs) with chiral modifiers were applied in the heterogeneous asymmetric dihydroxylation of alkenes. A remarkable size effect of the OsNPs, depending on the density of the covalent organic shells, on the reactivity and enantioselectivity of the dihydroxylation reaction was revealed. Successful recycling of the OsNPs was also demonstrated and high reaction efficiency and enantioselectivity were maintained.
- Zhu, Jie,Sun, Xiao-Tao,Wang, Xiao-Dong,Wu, Lei
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p. 1788 - 1792
(2018/04/30)
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- Alternative Strategies with Iodine: Fast Access to Previously Inaccessible Iodine(III) Compounds
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Non-iodinated arenes can be easily and selectively converted into (diacetoxyiodo)arenes in a single step under mild conditions by using iodine triacetates as reagents. The oxidative step is decoupled from the synthesis of hypervalent iodine(III) reagents, which can now be prepared conveniently in a one-pot synthesis for subsequent reactions without prior purification. The chemistry of iodine triacetates was also expanded to heteroatom ligand exchanges to form novel inorganic hypervalent iodine compounds.
- Hokamp, Tobias,Mollari, Leonardo,Wilkins, Lewis C.,Melen, Rebecca L.,Wirth, Thomas
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p. 8306 - 8309
(2018/06/29)
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- Multicore Artificial Metalloenzymes Derived from Acylated Proteins as Catalysts for the Enantioselective Dihydroxylation and Epoxidation of Styrene Derivatives
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Artificial metalloenzymes (AME′s) are an interesting class of selective catalysts, where the chiral environment of proteins is used as chiral ligand for a catalytic metal. Commonly, the active site of an enzyme is modified with a catalytically active metal. Here we present an approach, where the commercial proteins lysozyme (LYS) and bovine serum albumin (BSA) can be converted into highly active and enantioselective AME′s. This is achieved by acylation of the proteins primary amino groups, which affords the metal salts in the core of the protein. A series of differently acylated LYS and BSA were reacted with K2OsO2(OH)4, RuCl3, and Ti(OMe)4, respectively, and the conjugates were tested for their catalytic activity in dihydroxylation and epoxidation of styrene and its derivatives. The best suited system for dihydroxylation is fully acetylated LYS conjugated with K2OsO2(OH)4, which converts styrene to 1,2-phenylethanediol with an enantioselectivity of 95 % ee (S). BSA fully acylated with hexanoic acid and conjugated with three moles RuCl3 per mole protein shows the highest ee values for the conversion of styrene to the respective epoxide with enenatioselectivities of over 80 % ee (R), a TON of more than 2500 and a yield of up to 78 % within 24 h at 40 °C. LYS has two favored selective binding sites for the metal catalyst and BSA has even three. The AME′s with titanate in the active center invert the enantioselectivity of styrene epoxidation.
- Leurs, Melanie,Dorn, Bjoern,Wilhelm, Sascha,Manisegaran, Magiliny,Tiller, Joerg. C.
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supporting information
p. 10859 - 10867
(2018/08/03)
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- Asymmetric Allylic C-H Alkylation via Palladium(II)/ cis-ArSOX Catalysis
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We report the development of Pd(II)/cis-aryl sulfoxide-oxazoline (cis-ArSOX) catalysts for asymmetric C-H alkylation of terminal olefins with a variety of synthetically versatile nucleophiles. The modular, tunable, and oxidatively stable ArSOX scaffold is key to the unprecedented broad scope and high enantioselectivity (37 examples, avg. > 90% ee). Pd(II)/cis-ArSOX is unique in its ability to effect high reactivity and catalyst-controlled diastereoselectivity on the alkylation of aliphatic olefins. We anticipate that this new chiral ligand class will find use in other transition metal catalyzed processes that operate under oxidative conditions.
- Liu, Wei,Ali, Siraj Z.,Ammann, Stephen E.,White, M. Christina
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supporting information
p. 10658 - 10662
(2018/09/06)
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- Cis -Oxoruthenium complexes supported by chiral tetradentate amine (N4) ligands for hydrocarbon oxidations
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We report the first examples of ruthenium complexes cis-[(N4)RuIIICl2]+ and cis-[(N4)RuII(OH2)2]2+ supported by chiral tetradentate amine ligands (N4), together with a high-valent cis-dioxo complex cis-[(N4)RuVI(O)2]2+ supported by the chiral N4 ligand mcp (mcp = N,N′-dimethyl-N,N′-bis(pyridin-2-ylmethyl)cyclohexane-1,2-diamine). The X-ray crystal structures of cis-[(mcp)RuIIICl2](ClO4) (1a), cis-[(Me2mcp)RuIIICl2]ClO4 (2a) and cis-[(pdp)RuIIICl2](ClO4) (3a) (Me2mcp = N,N′-dimethyl-N,N′-bis((6-methylpyridin-2-yl)methyl)cyclohexane-1,2-diamine, pdp = 1,1′-bis(pyridin-2-ylmethyl)-2,2′-bipyrrolidine)) show that the ligands coordinate to the ruthenium centre in a cis-α configuration. In aqueous solutions, proton-coupled electron-transfer redox couples were observed for cis-[(mcp)RuIII(O2CCF3)2]ClO4 (1b) and cis-[(pdp)RuIII(O3SCF3)2]CF3SO3 (3c′). Electrochemical analyses showed that the chemically/electrochemically generated cis-[(mcp)RuVI(O)2]2+ and cis-[(pdp)RuVI(O)2]2+ complexes are strong oxidants with E° = 1.11-1.13 V vs. SCE (at pH 1) and strong H-atom abstractors with DO-H = 90.1-90.8 kcal mol-1. The reaction of 1b or its (R,R)-mcp counterpart with excess (NH4)2[CeIV(NO3)6] (CAN) in aqueous medium afforded cis-[(mcp)RuVI(O)2](ClO4)2 (1e) or cis-[((R,R)-mcp)RuVI(O)2](ClO4)2 (1e?), respectively, a strong oxidant with E(RuVI/V) = 0.78 V (vs. Ag/AgNO3) in acetonitrile solution. Complex 1e oxidized various hydrocarbons, including cyclohexane, in acetonitrile at room temperature, affording alcohols and/or ketones in up to 66% yield. Stoichiometric oxidations of alkenes by 1e or 1e? in tBuOH/H2O (5:1 v/v) afforded diols and aldehydes in combined yields of up to 98%, with moderate enantioselectivity obtained for the reaction using 1e?. The cis-[(pdp)RuII(OH2)2]2+ (3c)-catalysed oxidation of saturated C-H bonds, including those of ethane and propane, with CAN as terminal oxidant was also demonstrated.
- Tse, Chun-Wai,Liu, Yungen,Wai-Shan Chow, Toby,Ma, Chaoqun,Yip, Wing-Ping,Chang, Xiao-Yong,Low, Kam-Hung,Huang, Jie-Sheng,Che, Chi-Ming
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p. 2803 - 2816
(2018/03/21)
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- Kinetic Resolution of 1,2-Diols via NHC-Catalyzed Site-Selective Esterification
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A kinetic resolution of 1,2-diols bearing both a secondary and a primary alcohol motif through an N-heterocyclic carbene-catalyzed oxidative acylation reaction has been developed. A site- and enantioselective esterification reaction is involved for this process. Both the monoacylated diols obtained and the remaining enantioenriched 1,2-diols are versatile building blocks for the preparation of functional molecules with proven biological activities.
- Liu, Bin,Yan, Jiekuan,Huang, Ruoyan,Wang, Weihong,Jin, Zhichao,Zanoni, Giuseppe,Zheng, Pengcheng,Yang, Song,Chi, Yonggui Robin
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supporting information
p. 3447 - 3450
(2018/06/26)
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- Carbohydrate/DBU Cocatalyzed Alkene Diboration: Mechanistic Insight Provides Enhanced Catalytic Efficiency and Substrate Scope
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A mechanistic investigation of the carbohydrate/DBU cocatalyzed enantioselective diboration of alkenes is presented. These studies provide an understanding of the origin of stereoselectivity and also reveal a strategy for enhancing reactivity and broadening the substrate scope.
- Yan, Lu,Meng, Yan,Haeffner, Fredrik,Leon, Robert M.,Crockett, Michael P.,Morken, James P.
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supporting information
p. 3663 - 3673
(2018/03/21)
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- Alkylative kinetic resolution of vicinal diols under phase-transfer conditions: A chiral ammonium borinate catalysis
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Herein, we report the first alkylative kinetic resolution of vicinal alcohols realized by cooperative use of a chiral quaternary ammonium salt and an achiral borinic acid. In addition, a catalytic regioselective alkylation of a secondary alcohol in the presence of an unprotected primary one is presented, emphasizing the unique selectivity and potential of this ammonium borinate catalysis.
- Pawliczek, Martin,Hashimoto, Takuya,Maruoka, Keiji
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p. 1231 - 1235
(2018/02/09)
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- A carbonyl reductase from: Candida parapsilosis ATCC 7330: Substrate selectivity and enantiospecificity
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Candida parapsilosis ATCC 7330, a rich source of highly stereospecific oxidoreductases, catalyzes oxidation-reduction of a plethora of compounds yielding industrially important intermediates. An (S)-specific carbonyl reductase (SRED) purified and characterized from this yeast is reported here. (R)-Specific carbonyl reductase (CpCR) was reported by us earlier. SRED asymmetrically reduces ketones with excellent enantiospecificity (ee > 99%) and α-ketoesters with higher catalytic activity but moderate enantiospecificity (ee 70%) in the presence of NADPH. Minimal activity is shown towards the reduction of aldehydes. While the reduction of α-ketoesters with SRED can occur with either NADPH or NADH, for ketone reduction SRED requires NADPH specifically. SRED with a subunit molecular weight of 30 kDa shows optimal activity at pH 5.0 and 25 °C, and its activity is affected by Cu2+. Taken together, SRED and CpCR offer substrates which on asymmetric reduction give products of opposite absolute configurations.
- Sudhakara, Sneha,Chadha, Anju
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supporting information
p. 4165 - 4171
(2017/07/10)
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- Stereoselective Hydrolysis of Epoxides by reVrEH3, a Novel Vigna radiata Epoxide Hydrolase with High Enantioselectivity or High and Complementary Regioselectivity
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To provide more options for the stereoselective hydrolysis of epoxides, an epoxide hydrolase (VrEH3) gene from Vigna radiata was cloned and expressed in Escherichia coli. Recombinant VrEH3 displayed the maximum activity at pH 7.0 and 45 °C and high stability at pH 4.5-7.5 and 55 °C. Notably, reVrEH3 exhibited high and complementary regioselectivity toward styrene oxides 1a-3a and high enantioselectivity (E = 48.7) toward o-cresyl glycidyl ether 9a. To elucidate these interesting phenomena, the interactions of the three-dimensional structure between VrEH3 and enantiomers of 1a and 9a were analyzed by molecular docking simulation. Using E. coli/vreh3 whole cells, gram-scale preparations of (R)-1b and (R)-9a were performed by enantioconvergent hydrolysis of 100 mM rac-1a and kinetic resolution of 200 mM rac-9a in the buffer-free water system at 25 °C. These afforded (R)-1b with >99% eep and 78.7% overall yield after recrystallization and (R)-9a with >99% ees, 38.7% overall yield, and 12.7 g/L/h space-time yield.
- Hu, Die,Tang, Cunduo,Li, Chuang,Kan, Tingting,Shi, Xiaoling,Feng, Lei,Wu, Minchen
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p. 9861 - 9870
(2017/11/22)
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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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- Chiral Inductive Diastereoconvergent Friedel–Crafts Alkylation Reaction of Diastereomixtures of Diarylmethanols with 2-Naphthol Derivatives Catalyzed by SnBr4
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A highly diastereoconvergent Friedel–Crafts alkylation reaction of 2-naphthol derivatives with diastereomixtures of diarymethanols bearing a designed chiral auxiliary was achieved by using tin(IV) bromide as a catalyst in nitromethane under mild reaction conditions. The effects of various substituents located on the chiral auxiliary were evaluated, and chiral induction was found to take place via a carbocation through the chelation effect of an oxygen atom in a stereoconvergent manner. The chiral auxiliary was easily deprotected under conventional hydrogenation conditions without affecting the chirality of the starting material. A variety of substrates were transformed successfully, with high yields and selectivities (diastereomeric ratios ≥ 20:1) obtained irrespective of the substitution pattern and the electronic nature of the substrate aromatic rings.
- Suzuki, Nobuharu,Nakata, Kenya
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supporting information
p. 7075 - 7086
(2017/12/28)
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- Site-Directed Mutagenesis Studies on the Toluene Dioxygenase Enzymatic System: Role of Phenylalanine 366, Threonine 365 and Isoleucine 324 in the Chemo-, Regio-, and Stereoselectivity
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Toluene Dioxygenase (TDO) enzymatic complex has been widely used as a biocatalyst for the regio- and enantioselective preparation of cis-cyclohexadienediols, which are very important starting materials for organic synthesis. However, the lack of regio- and stereodiversity of the dioxygenation process by TDO and related dioxygenases constitutes a clear drawback when planning the use of these diols in synthetic schemes. In this work, we developed three TDO mutants in residues phenylalanine 366, threonine 365 and isoleucine 324, with the aim to alter the chemo-, regio- and stereoselectivity of the biotransformation of arenes. While no changes in the regioselectivity of the process were observed, dramatic variations in the chemo- and enantioselectivity were found for mutants I324F, T365N and F366 V in a substrate-dependent manner. (Figure presented.).
- Vila, María Agustina,Umpiérrez, Diego,Veiga, Nicolás,Seoane, Gustavo,Carrera, Ignacio,Rodríguez Giordano, Sonia
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p. 2149 - 2157
(2017/06/23)
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- Norepinephrine alkaloids as antiplasmodial agents: Synthesis of syncarpamide and insight into the structure-activity relationships of its analogues as antiplasmodial agents
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Syncarpamide 1, a norepinephrine alkaloid isolated from the leaves of Zanthoxylum syncarpum (Rutaceae) exhibited promising antiplasmodial activities against Plasmodium falciparum with reported IC50 values of 2.04 μM (D6 clone), 3.06 μM (W2 clone) and observed by us 3.90 μM (3D7 clone) and 2.56 μM (K1 clone). In continuation of our work on naturally occurring antimalarial compounds, synthesis of syncarpamide 1 and its enantiomer, (R)-2 using Sharpless asymmetric dihydroxylation as a key step has been accomplished. In order to study structure-activity-relationship (SAR) in detail, a library of 55 compounds (3–57), which are analogues/homologues of syncarpamide 1 were synthesized by varying the substituents on the aromatic ring, by changing the stereocentre at the C-7 and/or by varying the acid groups in the ester and/or amide side chain based on the natural product lead molecule and further assayed in vitro against 3D7 and K1 strains of P. falciparum to evaluate their antiplasmodial activities. In order to study the effect of position of functional groups on antiplasmodial activity profile, a regioisomer (S)-58 of syncarpamide 1 was synthesized however, it turned out to be inactive against both the strains. Two compounds, (S)-41 and its enantiomer, (R)-42 having 3,4,5-trimethoxy cinnamoyl groups as side chains showed better antiplasmodial activity with IC50 values of 3.16, 2.28 μM (3D7) and 1.78, 2.07 μM (K1), respectively than the natural product, syncarpamide 1. Three compounds (S)-13, (S)-17, (S)-21 exhibited antiplasmodial activities with IC50 values of 6.39, 6.82, 6.41 μM against 3D7 strain, 4.27, 7.26, 2.71 μM against K1 strain and with CC50 values of 147.72, 153.0, >200 μM respectively. The in vitro antiplasmodial activity data of synthesized library suggests that the electron density and possibility of resonance in both the ester and amide side chains increases the antiplasmodial activity as compared to the parent natural product 1. The natural product syncarpamide 1 and four analogues/homologues out of the synthesized library of 55, (S)-41, (R)-42, (S)-55 and (S)-57 were assayed in vivo assay against chloroquine-resistant P. yoelii (N-67) strain of Plasmodium. However, none of the five molecules, 1, (S)-41, (R)-42, (S)-55 and (S)-57 exhibited any promising in vivo antimalarial activity against P. yoelii (N-67) strain. Compounds 4, 6, 7 and 11 showed high cytotoxicities with CC50 values of 5.87, 5.08, 6.44 and 14.04 μM, respectively. Compound 6 was found to be the most cytotoxic as compared to the standard drug, podophyllotoxin whereas compounds 4 and 7 showed comparable cytotoxicities to podophyllotoxin.
- Aratikatla, Eswar K.,Valkute, Tushar R.,Puri, Sunil K.,Srivastava, Kumkum,Bhattacharya, Asish K.
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supporting information
p. 1089 - 1105
(2017/08/03)
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- Asymmetric Hydrolytic and Aminolytic Kinetic Resolution of Racemic Epoxides using Recyclable Macrocyclic Chiral Cobalt(III) Salen Complexes
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New chiral macrocyclic cobalt(III) salen complexes were synthesized and used as catalyst for the asymmetric kinetic resolution (AKR) of terminal epoxides and glycidyl ethers with aromatic/aliphatic amines and water as nucleophiles. This is the first occasion where a Co(III) salen complex demonstrated its ability to catalyze AKR as well as hydrolytic kinetic resolution (HKR) reactions. Excellent enantiomeric excesses of the epoxides, the corresponding amino alcohols and diols (upto 99%) with quantitative yields were achieved by using the chiral Co(III) salen complexes in dichloromethane at room temperature. This protocol was further extended for the synthesis of two important drug molecules, i.e., (S)-propranolol and (R)-naftopidil. The catalytic system was also explored for the synthesis of chirally pure diols and chiral cyclic carbonates using carbon dioxide as a greener renewable C1 source. The catalyst was recycled for upto 5 catalytic cycles with retention of enantioselectivity. (Figure presented.).
- Tak, Rajkumar,Kumar, Manish,Menapara, Tusharkumar,Gupta, Naveen,Kureshy, Rukhsana I.,Khan, Noor-ul H.,Suresh
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supporting information
p. 3990 - 4001
(2017/11/22)
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- Asymmetric hydrolysis of styrene oxide by PvEH2, a novel Phaseolus vulgaris epoxide hydrolase with extremely high enantioselectivity and regioselectivity
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A novel EH from Phaseolus vulgaris, PvEH2, was discovered based on the computer-aided analysis, and its encoding gene was cloned and expressed in E. coli Rossetta (DE3). The substrate spectrum of recombinant (re) PvEH2 was assayed, among which the enantiomeric ratio of rePvEH2 towards racemic styrene oxide (rac-1a) was > 200, while its regioselectivity coefficients, αS and βR, towards (S)- and (R)-1a were 99.1 and 69.8%, respectively. The asymmetric hydrolysis of 20 mM rac-1a by rePvEH2-expressing whole cells was performed at 25 °C, retaining (R)-1a with > 99.5% ees and 49.4% yield and producing (R)-phenyl-1,2-ethanediol (1b) with 96.2% eep and 49.7% yield in 40 min.
- Li, Chuang,Hu, Die,Zong, Xun-Cheng,Deng, Chao,Feng, Lei,Wu, Min-Chen,Li, Jian-Fang
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- Alternatives to Phosphinooxazoline (t-BuPHOX) Ligands in the Metal-Catalyzed Hydrogenation of Minimally Functionalized Olefins and Cyclic β-Enamides
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This study presents a new series of readily accessible iridium- and rhodium-phosphite/oxazoline catalytic systems that can efficiently hydrogenate, for the first time, both minimally functionalized olefins and functionalized olefins (62 examples in total) in high enantioselectivities (ees up to >99%) and conversions. The phosphite-oxazoline ligands, which are readily available in only two synthetic steps, are derived from previous privileged 4-alkyl-2-[2-(diphenylphosphino)phenyl]-2-oxazoline (PHOX) ligands by replacing the phosphine moiety by a biaryl phosphite group and/or the introduction of a methylene spacer between the oxazoline and the phenyl ring. The modular design of the ligands has given us the opportunity not only to overcome the limitations of the iridium-PHOX catalytic systems in the hydrogenation of minimally functionalized Z-olefins and 1,1-disubstituted olefins, but also to expand their use to unfunctionalized olefins containing other challenging scaffolds (e.g., exocyclic benzofused and triaryl-substituted olefins) and also to olefins with poorly coordinative groups (e.g., α,β-unsaturated lactams, lactones, alkenylboronic esters, etc.) with enantioselectivities typically >95% ee. Moreover, both enantiomers of the hydrogenation product could be obtained by simply changing the configuration of the biaryl phosphite moiety. Remarkably, the new catalytic systems also provided excellent enantioselectivities (up to 99% ee) in the asymmetric hydrogenation of another challenging class of olefins – the functionalized cyclic β-enamides. Again, both enantiomers of the reduced amides could be obtained by changing the metal from Ir to Rh. We also demonstrated that environmentally friendly propylene carbonate can be used with no loss of enantioselectivity. Another advantage of the new ligands over the PHOX ligands is that the best ligands are derived from the affordable (S)-phenylglycinol rather than from the expensive (S)-tert-leucinol. (Figure presented.).
- Biosca, Maria,Magre, Marc,Coll, Mercè,Pàmies, Oscar,Diéguez, Montserrat
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supporting information
p. 2801 - 2814
(2017/08/23)
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- Enantioselective Vicinal Diacetoxylation of Alkenes under Chiral Iodine(III) Catalysis
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A procedure for the intermolecular enantioselective dioxygenation of alkenes under iodine(III) catalysis has been developed. This protocol employs Selectfluor as the terminal oxidant together with a defined C 2-symmetric aryl iodide as the organocatalyst. This enantioselective reaction proceeds under mild conditions and converts a series of terminal and internal styrenes into the corresponding vicinal diacetoxylation products with up to 96% ee.
- W?ste, Thorsten H.,Mu?iz, Kilian
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p. 816 - 827
(2016/03/15)
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- Chiral N-heterocyclic carbene iridium catalyst for the enantioselective hydrosilane reduction of ketones
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Enantioselective reduction of ketones with (EtO)2MeSiH catalyzed by an in-situ generated N-heterocyclic carbene (NHC) Ir complex at room temperature has been developed. A series of benzimidazolium salts were synthesized and screened in the asymmetric hydrosilylation reaction. As a result, propiophenone was efficiently reduced by the combined catalytic system of [IrCl(cod)]2 and NHC-Ag complex derived from N-(1-naphthalenylmethyl)-substituted benzimidazolium salt L12, affording the corresponding alcohol in 92% yield and with 92% ee. Moreover, the evaluation of an Ir catalyst precursor showed that cationic [Ir(cod)2]BF4 complex could be used. Furthermore, the introduction of a chiral hydroxyamide side arm into the benzimidazolium salt was critical for the successful design of the NHC ligand.
- Manabe, Yoshiki,Shinohara, Kanako,Nakamura, Hanako,Teramoto, Hiro,Sakaguchi, Satoshi
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p. 138 - 145
(2016/06/15)
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- HPLC enantioseparation on a homochiral MOF-silica composite as a novel chiral stationary phase
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The last frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal-organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performance liquid chromatography to separate the enantiomers of various kinds of racemic sulfoxides, sec-alcohols, β-lactams, benzoins, flavanones and epoxides. The experimental results showed excellent performances for enantioseparation, and highlighted that enantioseparation on homochiral MOF columns is practical.
- Tanaka, Koichi,Muraoka, Toshihide,Otubo, Yasuhiro,Takahashi, Hiroki,Ohnishi, Atsushi
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p. 21293 - 21301
(2016/03/08)
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