- Method for synthesizing benserazide hydrochloride by utilizing fixed bed hydrogenation equipment
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The invention discloses a method for synthesizing benserazide hydrochloride by using fixed bed hydrogenation equipment, which is characterized in that a compound 1 reacts with an amino protective agent to carry out an amino protection reaction, so that the subsequent purification is easy, and the dosage of hydrazine hydrate in the synthesis method is small; according to the method, fixed bed hydrogenation equipment is used for synthesis, a fixed bed reactor is filled with a solid catalyst or a solid to realize a heterogeneous reaction process, the catalyst in the fixed bed reactor is relatively fixed, a reaction liquid flows through a bed layer, and the reaction liquid flows through the bed layer by adjusting the flow rate and the reaction pressure; qualified products can be obtained after reaction liquid flows out of the fixed bed, continuous production can be achieved, product deterioration caused by long-time contact of the products and the catalyst can be avoided, the same amount of products can be produced due to continuous production, the reactor size can be very small, the safety problem caused by high-pressure reaction is greatly reduced, the amount of the catalyst used in the reaction is less, and the production cost is reduced.
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Paragraph 0028-0031; 0042-0045; 0056-0059
(2021/06/02)
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- Rational design of triplet sensitizers for the transfer of excited state photochemistry from UV to visible
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Time Dependent Density Functional Theory has been used to assist the design and synthesis of a series thioxanthone triplet sensitizers. Calculated energies of the triplet excited state (ET) informed both the type and position of auxochromes placed on the thioxanthone core, enabling fine-tuning of the UV-vis absorptions and associated triplet energies. The calculated results were highly consistent with experimental observation in both the order of the λmax and ET values. The synthesized compounds were then evaluated for their efficacies as triplet sensitizers in a variety of UV and visible light preparative photochemical reactions. The results of this study exceeded expectations; in particular [2 + 2] cycloaddition chemistry that had previously been sensitized in the UV was found to undergo cycloaddition at 455 nm (blue) with a 2- to 9-fold increase in productivity (g/h) relative to input power. This study demonstrates the ability of powerful modern computational methods to aid in the design of successful and productive triplet sensitized photochemical reactions.
- Booker-Milburn, Kevin,Elliott, Luke D.,George, Michael W.,Kayal, Surajit
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supporting information
p. 14947 - 14956
(2020/10/13)
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- Synthesizing method using serine to prepare Ramipril key intermediate
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The invention relates to a synthesizing method using serine to prepare a Ramipril key intermediate. The Ramipril key intermediate is 2-azabicyclo[3.3.0] octane-3-carboxylic acid hydrochloride or benzyl ester hydrochloride. The synthesizing method includes: using the serine as the initial raw material, and sequentially performing esterification, acyl chloride acylation, deacidification, Michael addition, hydrolysis and hydrogenation reduction to obtain the Ramipril key intermediate. The synthesizing method has the advantages that the key intermediate is synthesized by a five-step method, and the synthesizing method is cheap in raw material, environmentally friendly, simple in preparation process, simple to operate, mild in reaction condition, short in reaction cycle, convenient in post-treatment, low in equipment requirement, capable of avoiding heavy metal pollution and the use of expensive catalysts, few in three wastes, high in product yield and purity and suitable for industrial production.
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Paragraph 0048; 0049
(2016/10/10)
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- Dehydrodipeptide Hydrogelators Containing Naproxen N-Capped Tryptophan: Self-Assembly, Hydrogel Characterization, and Evaluation as Potential Drug Nanocarriers
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In this work, we introduce dipeptides containing tryptophan N-capped with the nonsteroidal anti-inflammatory drug naproxen and C-terminal dehydroamino acids, dehydrophenylalanine (ΔPhe), dehydroaminobutyric acid (ΔAbu), and dehydroalanine (ΔAla) as efficacious protease resistant hydrogelators. Optimized conditions for gel formation are reported. Transmission electron microscopy experiments revealed that the hydrogels consist of networks of micro/nanosized fibers formed by peptide self-assembly. Fluorescence and circular dichroism spectroscopy indicate that the self-assembly process is driven by stacking interactions of the aromatic groups. The naphthalene groups of the naproxen moieties are highly organized in the fibers through chiral stacking. Rheological experiments demonstrated that the most hydrophobic peptide (containing C-terminal ΔPhe) formed more elastic gels at lower critical gelation concentrations. This gel revealed irreversible breakup, while the C-terminal ΔAbu and ΔAla gels, although less elastic, exhibited structural recovery and partial healing of the elastic properties. A potential antitumor thieno[3,2-b]pyridine derivative was incorporated (noncovalently) into the gel formed by the hydrogelator containing C-terminal ΔPhe residue. Fluorescence and F?rster resonance energy transfer measurements indicate that the drug is located in a hydrophobic environment, near/associated with the peptide fibers, establishing this type of hydrogel as a good drug-nanocarrier candidate.
- Vila?a, Helena,Hortel?o, Ana C. L.,Castanheira, Elisabete M. S.,Queiroz, Maria-Jo?o R. P.,Hilliou, Loic,Hamley, Ian W.,Martins, José A.,Ferreira, Paula M. T.
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p. 3562 - 3573
(2015/11/17)
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- ANTIMICROBIAL COMPOUNDS
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The present invention relates to certain tetramic acid derivatives and, in particular, bicyclic tetramic acid derivatives that are suitable for use in the preparation and development of antimicrobial (e.g. antibacterial or antifungal) compositions.The present invention also relates to the use of such compounds as antimicrobial (e.g. antibacterial or antifungal agents) and, in particular, as topical antibacterial or antifungal agents.
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Paragraph 00117
(2014/01/17)
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- Preparation of D-cycloserine and 13C-labeled D-cycloserine
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D-Cycloserine (DCS), a second stage drug for the treatment of tuberculosis, is synthesized in 19.8% overall yield from DL-serine methyl ester. This synthetic route gives both enantiomers of cycloserine via a corrected and improved one pot resolution procedure using D- and L-tartaric acids. The route is used to synthesize a 13C-labeled derivative for use in biological studies.
- Thacker, Nathan C.,Molnar-Toth, Judit,Miska, Judy L.,Barletta, Raul G.,Takacs, James M.
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p. 1575 - 1582
(2013/08/23)
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- Efficient regio- And stereoselective formation of azocan-2-ones via 8-endo cyclization of α-carbamoyl radicals
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The iodine-atom-transfer 8-endo cyclization of α-carbamoyl radicals was investigated experimentally and theoretically. With the aid of Mg(CIO 4)2 and a bis(oxazoline) ligand, N- ethoxycarbonylsubstituted N-(pent-4-enyl)-2-iodoalkanamides underwent 8-endo cyclization leading to the formation of only the corresponding 3,5-trans-substituted azocan-2-ones in excellent yields. Similarly, the BF 3·OEt2/H2O-promoted reactions of N-ethoxycarbonyl-N-(2-allylaryl)-2-iodoalkanamides afforded exclusively the benzazocanone products with a 3,5-cis configuration in high yields. The bidentate chelation of substrate radicals not only significantly improved the efficiency of cyclization but also resulted in the change of stereochemistry of azocanone products from 3,8-iransto 3,8-cis. Theoretical calculations at the UB3LYP/6-31G* level revealed that the cyclization of N-carbonyl- substituted α-carbamoyl radicals occurs via the E-conformational transition states without the presence of a Lewis acid. On the other hand, the cyclization proceeds via the Z-conformational transition states when the substrates form the bidentate chelation with a Lewis acid. In both cases, the 8-endo cyclization is always fundamentally preferred over the corresponding 7-exo cyclization. The complexed radicals having the more rigid conformations also allow the better stereochemical control in the iodine-atom-abstraction step. To further understand the reactivity of a-carbamoyl radicals, the competition between the 8-endo and 5-exo cyclization was also studied. The results demonstrated that the 8-endo cyclization is of comparable rate to the corresponding 5-exo cyclization for a-carbamoyl radicals with fixed Z-conformational transition states. As a comparison, the 8-endo mode is fundamentally preferred over the 5-exo mode in the cyclization of NH-amide substrates because the latter requires the Z-conformational transition states, whereas the former proceeds via the more stable E-conformational transition states.
- Fang, Xinqiang,Liu, Kun,Li, Chaozhong
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supporting information; experimental part
p. 2274 - 2283
(2010/05/01)
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- Nitrate esters in the generation of amino acid radicals
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Nitrate esters, prepared by treatment of β-hydroxy-α-amino acid derivatives with nitric acid, react with tributyltin hydride to give the corresponding alkoxyl radicals. These radicals readily undergo β-scission, providing a convenient route for the regiocontrolled production of α-carbon-centred amino acid radicals. By examining the partitioning of the alkoxyl radicals between the β-scission process and the competing hydrogen transfer reaction, it has been possible to evaluate the influence of electronic and steric effects on the β-scission reaction and the formation of the carbon-centred radicals.
- Easton, Christopher J.,Ivory, Andrew J.,Smith, Craig A.
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p. 503 - 507
(2007/10/03)
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- Synthesis of a Phosphinic Acid Transition State Analogue Inhibitor of Dihydroorotase
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The synthesis of the phosphinic acid 4-hydroxy-6-oxo-1,4-azaphosphinane-2-carboxylic acid 4-oxide (11) is described.The phosphinic acid (11) was designed as a transition state analogue inhibitor of dihydroorotase.
- Cao, Yu,Christopherson, Richard I.,Elix, John A.,Gaul, Kim L.
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p. 903 - 912
(2007/10/02)
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- AMINO ACIDS; 13. INVESTIGATIONS ON THE SYNTHESIS OF DL-SERINE FROM α-HALOACRYLIC ACID DERIVATIVES
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The alkoxide-catalyzed addition of alcohols 2 to α-chloroacrylonitrile (1) at -35 degC gives rise to 3-alkoxy-2-chloropropanenitriles 3; at 0-5 degC with excess 2 alkyl 3-alkoxy-2-chloropropanimidates 4 are obtained.The yields of 3 or 4 decrease with increasing pKa values of the alcohols 2.In the basecatalyzed addition of phenols 5 to 1, a temperature-dependent addition equilibrium is set up in which the position of equilibrium is shifted in favour of the addition products 6 with increasing pKa values of 5.The 3-alkoxy-2-chloropropanoates 8, which are readily accessible by hydrolysis of 4, react smoothly with sodium azide in the presence of a phase transfer catalyst to furnish the 3-alkoxy-2-azidopropanoates 10.Starting from benzyl 2-azido-3-benzyloxy-propanoate (10b), the specific syntheses of DL-serine (14), DL-serine hydrochloride (14*HCl), DL-serine methyl ester hydrochloride (13a*HCl), O-benzyl-DL-serine (12b), and O-benzyl-DL-serine benzyl ester hydrochloride (11b*HCl) are possible by variation of the hydrogenation conditions.
- Effenberger, Franz,Zoller, Gerhard
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p. 5573 - 5582
(2007/10/02)
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