- Highly Stable Zr(IV)-Based Metal-Organic Frameworks for Chiral Separation in Reversed-Phase Liquid Chromatography
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Separation of racemic mixtures is of great importance and interest in chemistry and pharmacology. Porous materials including metal-organic frameworks (MOFs) have been widely explored as chiral stationary phases (CSPs) in chiral resolution. However, it remains a challenge to develop new CSPs for reversed-phase high-performance liquid chromatography (RP-HPLC), which is the most popular chromatographic mode and accounts for over 90% of all separations. Here we demonstrated for the first time that highly stable Zr-based MOFs can be efficient CSPs for RP-HPLC. By elaborately designing and synthesizing three tetracarboxylate ligands of enantiopure 1,1′-biphenyl-20-crown-6, we prepared three chiral porous Zr(IV)-MOFs with the framework formula [Zr6O4(OH)8(H2O)4(L)2]. They share the same flu topological structure but channels of different sizes and display excellent tolerance to water, acid, and base. Chiral crown ether moieties are periodically aligned within the framework channels, allowing for stereoselective recognition of guest molecules via supramolecular interactions. Under acidic aqueous eluent conditions, the Zr-MOF-packed HPLC columns provide high resolution, selectivity, and durability for the separation of a variety of model racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation. DFT calculations suggest that the Zr-MOF provides a confined microenvironment for chiral crown ethers that dictates the separation selectivity.
- Jiang, Hong,Yang, Kuiwei,Zhao, Xiangxiang,Zhang, Wenqiang,Liu, Yan,Jiang, Jianwen,Cui, Yong
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- Rhodium-catalyzed asymmetric hydrogenation of β-cyanocinnamic esters with the assistance of a single hydrogen bond in a precise position
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With the assistance of hydrogen bonds, the first asymmetric hydrogenation of β-cyanocinnamic esters is developed, affording chiral β-cyano esters with excellent enantioselectivities (up to 99% ee). This novel methodology provides an efficient and concise synthetic route to chiral GABA-derivatives such as (S)-Pregabalin, (R)-Phenibut, (R)-Baclofen. Interestingly, in this system, the catalyst with a single H-bond donor performs better than that with double H-bond donors, which is a novel discovery in the metalorganocatalysis area.
- Li, Xiuxiu,You, Cai,Yang, Yusheng,Yang, Yuhong,Li, Pan,Gu, Guoxian,Chung, Lung Wa,Lv, Hui,Zhang, Xumu
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- Synthesis and Biological Analysis of Anti-addiction Effect and Hepatotoxicity of Tow Baclofen Analogues Complexed with β-Cyclodextrin
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Aim and Objective: The excessive consumption of alcohol and the installation of dependence is, in most cases, facilitated by favorable psychological factors that trigger and maintain the behavior of consumers. Examples more frequently encountered in individuals having difficulty with alcohol are, in particular: one or more anxiety disorders, deficits in the capacities to manage stress and anxiety. The main objective of this work was to study in vivo the anti-addiction effect and hepatotoxicity of tow baclofen analogues complexed with β-Cyclodextrin (βCD) on an alcohol-dependent rat model. Materials and Methods: The synthesis of two analogues, ABF1 and ABF2, close to baclofen was reported. The structural determination of the two compounds was confirmed by NMR and IR analysis. The complexation of analogues with β-Cyclodextrin (βCD) was performed in water at room temperature (25 °C). The interactions of ABF with β-Cyclodextrin, and the stability constant (Ka) of the inclusion complex formed between them were investigated by using UV-visible spectroscopy. The biological effects of baclofen and the two analogues on alcohol dependence were studied in wistar rats. The anti-addiction effect of the analogues was tested by measuring the alcohol intake and the variation of the animal behaviour. The toxicity of the compounds was also analysed on liver injury markers. Results: The amino-3-phenylbutanoic acid (ABF1) and 3,4,5-trihydroxy-N-(methyl-2-acetate) benzamide (ABF2) were synthesized. The complexation of both analogues of baclofen (BF) with β-cyclodextrin (βCD) (ABF-βCD) was realized and confirmed by the stability constant of the inclusion complex (Ka) and Job’s method. The evaluation of anti-addiction activity in vivo showed that ABF1-βCD inhibits the consumption of alcohol at doses equivalent to those of baclofen. Both baclofen analogues have shown an anxiolytic effect. Regarding the toxicity of the two compounds, our results showed that ABF1-βCD has less toxic effect than baclofen; it reduces the activity of ALT and AST enzymes. Histologically, ABF1-βCD has no effect on the liver structure and has a protective effect against lesions alcohol-induced liver disease. Conclusion: Therefore, it can be suggested that ABF1 analogue combined with β-Cyclodextrin can be used as a treatment for alcohol dependence. Further clinical works are needed to confirm its effectiveness.
- Dib, Mohammed El Amine,El Ouar, Ibtissem,Keniche, Assia,Zeghina, Ibtissem
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p. 187 - 196
(2022/02/02)
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- Catalytic Intermolecular Carboamination of Unactivated Alkenes via Directed Aminopalladation
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An intermolecular 1,2-carboamination of unactivated alkenes proceeding via a Pd(II)/Pd(IV) catalytic cycle has been developed. To realize this transformation, a cleavable bidentate directing group is used to control the regioselectivity of aminopalladation and stabilize the resulting organopalladium(II) intermediate, such that oxidative addition to a carbon electrophile outcompetes potential β-hydride elimination. Under the optimized reaction conditions, a broad range of nitrogen nucleophiles and carbon electrophiles are compatible coupling partners in this reaction, affording moderate to high yields. The products of this reaction can be easily converted to free ?3-amino acids and ?3-lactams, both of which are common structural motifs found in drug molecules and bioactive compounds. Reaction kinetics and DFT calculations shed light on the mechanism of the reaction and explain empirically observed reactivity trends.
- Liu, Zhen,Wang, Yanyan,Wang, Zichen,Zeng, Tian,Liu, Peng,Engle, Keary M.
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supporting information
p. 11261 - 11270
(2017/08/22)
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- Chemical assembly systems: Layered control for divergent, continuous, multistep syntheses of active pharmaceutical ingredients
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While continuous chemical processes have attracted both academic and industrial interest, virtually all active pharmaceutical ingredients (APIs) are still produced by using multiple distinct batch processes. To date, methods for the divergent multistep continuous production of customizable small molecules are not available. A chemical assembly system was developed, in which flow-reaction modules are linked together in an interchangeable fashion to give access to a wide breadth of chemical space. Control at three different levels - choice of starting material, reagent, or order of reaction modules - enables the synthesis of five APIs that represent three different structural classes (γ-amino acids, γ-lactams, β-amino acids), including the blockbuster drugs Lyrica and Gabapentin, in good overall yields (49-75%).
- Ghislieri, Diego,Gilmore, Kerry,Seeberger, Peter H.
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p. 678 - 682
(2015/03/04)
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- SYNTHESIS OF THERAPEUTIC AND DIAGNOSTIC DRUGS CENTERED ON REGIOSELECTIVE AND STEREOSELECTIVE RING OPENING OF AZIRIDINIUM IONS
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Stereoselective and regioselective synthesis of compounds via nucleophilic ring opening reactions of aziridinium ions for use in stereoselective and regioselective synthesis of therapeutic and diagnostic compounds.
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- A short and convenient chemoenzymatic synthesis of both enantiomers of 3-phenylGABA and 3-(4-chlorophenyl)GABA(Baclofen)
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Both enantiomers of the pharmacologically active GABA analogues 4-amino-3-phenyl and 4-amino-3-(4-chlorophenyl)butyric acid (Baclofen) with high enantiomeric excesses were synthesized by a chemoenzymatic method involving α-chymotrypsin mediated kinetic resolutions of the corresponding 3-phenyl- and 3-(4-chlorophenyl)-4-nitrobutyric acid methyl ester precursors.
- Felluga, Fulvia,Gombac, Valentina,Pitacco, Giuliana,Valentin, Ennio
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p. 1341 - 1345
(2007/10/03)
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- Use of GABA and GABAB agonists
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The present invention provides methods of stimulating tissue growth, including islet cell growth, by administering GABA or a GABA agonist to act on GABAB receptors and GABAB-like receptors to activate cell replication.
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- Enzymatic desymmetrization of 3-alkyl- and 3-arylglutaronitriles, a simple and convenient approach to optically active 4-amino-3-phenylbutanoic acids
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The enantioselective hydrolysis of 3-alkyl- and 3-arylglutaronitriles catalyzed by Rhodococcus sp. AJ270 cells, afforded the corresponding (S)-3-substituted 4-cyanobutanoic acids with low to moderate enantiomeric purities. Additives such as acetone were found to significantly enhance the enantioselectivity of the desymmetrization, giving enantiomeric excesses of up to 95%. The synthetic potential of the homochiral product was also demonstrated by the preparation of optically active (R)- and (S)-4-amino-3-phenylbutanoic acids.
- Wang, Mei-Xiang,Liu, Chu-Sheng,Li, Ji-Sheng
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p. 3367 - 3373
(2007/10/03)
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- Enantioselective synthesis of β-substituted primary and secondary amines by alkylation of (R)-phenylglycinol amide enolates
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General and convenient syntheses of optically active β-substituted secondary or primary amines 4 and 8 are described. The method is based on diastereoselective alkylation of amides 1 and 5 derived from R-(-)-phenylglycinol followed by reduction and removal of the chiral appendage. This procedure has also been applied to the preparation of 1,4-amino alcohols 12 and γ-amino esters 14.
- Jullian, Valérie,Quirion, Jean-Charles,Husson, Henri-Philippe
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p. 1091 - 1097
(2007/10/03)
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- Enantioselective syntheses of (R)-3-phenyl GABA, (R)-baclofen and 4-arylpyrrolidin-2-ones
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Enantioselective synthesis of (R)-4-amino-3-phenylbutyric acid and (R)-baclofen has been achieved through a diastereoselective conjugate addition of cyanide to enantiomerically pure 2-(2-arylethenyl)oxazolines, followed by chemoselective reduction into cyclic amidines.
- Langlois, Nicole,Dahuron, Nathalie,Wang, Hai-Shan
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p. 15117 - 15126
(2007/10/03)
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- A NEW SYNTHESIS, RESOLUTION AND IN VITRO ACTIVITIES OF (R)- AND (S)-β-PHENYL-GABA
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β-Phenyl-GABA (2) was resolved by separation by crystallization and/or h.p.l.c. of the diastereoisomeric (R)-(-)-pantolactone esters of the N-phthalimido protected β-phenyl-GABA.The absolute stereochemical assignments obtained from chiroptical studies of the enantiomers (8a) and (8b) and an X-ray crystallographic study of the diastereoisomer (7a) were supported by the activities of the enantiomers (8a) and (8b) in binding and electrophysiological studies.Details of synthesis, binding, electrophysiological, chiroptical and X-ray crystallographic studies are reported.
- Allan, R. D.,Bates, M. C.,Drew, C. A.,Duke, R. K.,Hambley, T. W.,et al.
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p. 2511 - 2524
(2007/10/02)
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