- Selecting optimal conditions for Alcalase CLEA-OM for synthesis of dipeptides in organic media
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In protease-catalyzed peptide synthesis, the availability of water is essential, as a compromise must be made between on the one hand the overall enzymatic activity and, on the other hand, the rate of product synthesis. Water is essential for enzyme activity, but at the same time causes hydrolytic side reactions. We studied the coupling of the carbamoylmethyl ester of N-protected phenylalanine and phenylalanine amide in tetrahydrofuran catalyzed by Alcalase CLEA-OM at a range of water activity (aw) values, including the coupling in the presence of molecular sieves (i.e. at very low aw values). The hydrolytic side reaction (in the present system only the hydrolysis of substrate occurs) was found to dominate above an aw value of about 0.2. To prevent hydrolysis, the presence of molecular sieves was found to be necessary.
- Vossenberg,Beeftink,Nuijens,Cohen Stuart,Tramper
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- Aryl hydrazides as linkers for solid phase synthesis which are cleavable under mild oxidative conditions
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We have developed an acid/base stable aryl hydrazide linker which is readily coupled to solid phase resins. Cleavage is specific and facile, requiring a copper (II) catalyst, base and a nucleophile to proceed. The conditions are compatible with all 20 proteinogenic amino acids and quantitative cleavage is achieved within 2 hours at 20°C to give peptides with C-terminal acid, amide or ester functionalities. Aryl hydrazides also offer scope as simple 'traceless' linkers.
- Millington, Christopher R.,Quarrell, Rachel,Lowe, Gordon
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- Peptiligase, an Enzyme for Efficient Chemoenzymatic Peptide Synthesis and Cyclization in Water
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We describe a novel, organic cosolvent-stable and cation-independent engineered enzyme for peptide coupling reactions. The enzyme is a variant of a stable calcium-independent mutant of subtilisin BPN′, with the catalytic Ser212 mutated to Cys and Pro216 converted to Ala. The enzyme, called peptiligase, catalyzes exceptionally efficient peptide coupling in water with a surprisingly high synthesis over hydrolysis (S/H) ratio. The S/H ratio of the peptide ligation reaction is correlated to the length of the peptide substrate and proved to be >100 for the synthesis of a 13-mer peptide, which corresponds to >99% conversion to the ligated peptide product and 1% hydrolytic side-reaction. Furthermore, peptiligase does not require a particular recognition motif resulting in a broadly applicable and traceless peptide ligation technology. Peptiligase is very robust, easy to produce in Bacillus subtilis, and its purification is straightforward. It shows good activity and stability in the presence of organic cosolvents and chelating or denaturing agents, enabling the ligation of poorly soluble (hydrophobic) or folded peptides. This enzyme could be useful for the (industrial) synthesis of diverse (pharmaceutical) peptides. In addition, peptiligase is able to efficiently catalyze head-to-tail peptide cyclization reactions. (Figure presented.) .
- Toplak, Ana,Nuijens, Timo,Quaedflieg, Peter J. L. M.,Wu, Bian,Janssen, Dick B.
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- A transient non-covalent hydrogel by a supramolecular gelator with dynamic covalent bonds
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Nature operates out of equilibrium, which needs a continuous input of energy. However, on the removal of the energy source, the system returns to its thermodynamically stable building blocks, resulting in an aggregation-to-nonaggregation transition. The control of this system is governed by kinetics. Herein, we have alleviated that system using a supramolecular gelator with dynamic covalent bonds. In the aqueous solution of benzyloxycarbonyl-l-phenylalanine (ZF), equilibrium self-assembly and gelation take place at 4 mg mL?1; however, on the addition of 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC), non-equilibrium hydrogels are formed at 2 mg mL?1due to anhydride formation and self-assembly. However, with time, the hydrolysis of anhydride results in a gel-to-sol transition. The dynamic covalent bond formation and rupture have programmed the dissipative, transient supramolecular hydrogels from ZF with a high degree of control over the self-assembly lifetime. The system is not fully dissipative as it does not spontaneously oscillate between two states, but needs fuel to undergo a transition. The refueling of the system with EDC helps to access multiple cycles.
- Mondal, Sahabaj,Haldar, Debasish
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- Can self-assembled hydrogels composed of aromatic amino acid derivatives function as drug delivery carriers?
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Low molecular weight hydrogelators (LMOHGs) have attracted recent attention due to their diversified applications. In an attempt to artificially imitate their importance in the design of drug delivery carriers, we have synthesized two simple N-terminally protected aromatic amino-acid derivatives that form efficient stable hydrogels at room temperature. The gelation properties of the hydrogels have been thoroughly investigated using various techniques and their strength has been determined by rheological studies. In order to explore the efficacy of the hydrogels as tools for drug delivery, we have developed hydrogel nanoparticles (HNPs) using a surfactant and high-speed homogenization approach. Interestingly, our hydrogel nanoparticles display good entrapment efficiency and release kinetics of the model drug 5-fluoro uracil from the hydrogel matrix. Our experimental results reveal that hydrogel II displays slightly higher efficiency as a drug delivery carrier, which may be due to the presence of an aromatic ring in the backbone in comparison to hydrogel I. This increased strength may be attributed to the increase in π-π interactions when the aromatic residue is present in the backbone. Therefore the nanoparticles generated from hydrogel II may have better hydrogen bonding abilities with drugs in comparison to hydrogel I; thus resulting in a slightly slower release of drug from the hydrogel matrix. This fact may shed some light on the candidature of our hydrogels as future carriers for drug delivery. However, further studies to evaluate the candidature of these novel types of aromatic amino acid hydrogel nanoparticles for nano-medical applications are under investigation.
- Tiwari, Priyanka,Rajagopalan, Ramanathan,Moin, Mohammad,Soni, Rohit,Trivedi, Piyush,DuttKonar, Anita
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- STEREOSELECTIVE MICELLAR CATALYSIS IN THE HYDROLYSIS OF ENANTIOMERIC ESTERS BY DIPEPTIDE DERIVATIVES CONTAINING HISTIDINE RESIDUE
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The catalytic hydrolysis of enantiomeric substrates is examined using optically active dipeptide derivatives containing histidine residue in the presence of CTABr micelles.A very high stereoselectivity, kc(L)/kc(D), of 12.2 is observed in the reaction with the enantiomers of p-nitrophenyl N-methoxycarbonylphenylalanate (MocPheONp) and N-(benzyloxycarbonyl-L-leucyl)-L-histidine (ZLeuHis).
- Ihara, Yasuji,Kunikiyo, Noriko,Kunimasa, Tomoko,Nango, Mamoru,Kuroki, Nobuhiko
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- Substrate specificity of an actively assembling amyloid catalyst
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In the presence of Zn2+, the catalytic, amyloid-forming peptide Ac-IHIHIQI-NH2, was found to exhibit enhanced selectivity for hydrophobic p-nitrophenyl ester substrates while in the process of self-assembly. As opposed to the substrate p-nitrophenyl acetate, which was more effectively hydrolyzed with Ac-IHIHIQI-NH2 in its fully fibrillar state, the hydrophobic substrate Z-L-Phe-ONp was converted with a second-order rate constant more than 11-times greater when the catalyst was actively assembling. Under such conditions, Z-L-Phe-ONp hydrolysis proceeded at a greater velocity than the more hydrophilic and otherwise more labile ester Boc-L-Asn-ONp. When assembling, the catalyst also showed increased selectivity for the L-enantiomer of Z-Phe-ONp. These findings suggest the occurrence of increased interactions of hydrophobic moieties of the substrate with exposed hydrophobic surfaces of the assembling peptides and present valuable features for future de novo design consideration.
- Heier, Jason L.,Mikolajczak, Dorian J.,B?ttcher, Christoph,Koksch, Beate
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- Bottom-Up Construction of an Adaptive Enzymatic Reaction Network
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The reproduction of emergent behaviors in nature using reaction networks is an important objective in synthetic biology and systems chemistry. Herein, the first experimental realization of an enzymatic reaction network capable of an adaptive response is reported. The design is based on the dual activity of trypsin, which activates chymotrypsin while at the same time generating a fluorescent output from a fluorogenic substrate. Once activated, chymotrypsin counteracts the trypsin output by competing for the fluorogenic substrate and producing a non-fluorescent output. It is demonstrated that this network produces a transient fluorescent output under out-of-equilibrium conditions while the input signal persists. Importantly, in agreement with mathematical simulations, we show that optimization of the pulse-like response is an inherent trade-off between maximum amplitude and lowest residual fluorescence.
- Helwig, Britta,van Sluijs, Bob,Pogodaev, Aleksandr A.,Postma, Sjoerd G. J.,Huck, Wilhelm T. S.
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- Aqueous Solutions Containing Amino Acids and Peptides. Part 17. --Pairwise Enthalpic Coefficients for the Interaction of N-Acetyl-L-Phenylalaninamide with some N-Acetylamino Acid Amines at 25 deg C
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Enthalpies of dilution of N-acetyl-L-phenylalaninamide and equimolal solutions of this with N-acetylglycinamide, N-acetyl-L-alaninamide, N-acetyl- L-valinamide and N-acetyl-L-leucinamide have been determined using microcalorimetry.The results obtained were used to calculate the pairwise enthalpic coefficients for both like-like (homotactic) and like-unlike (heterotactic) solute interactions.These were then used with a group-additivity approach, which works well for these systems, to obtain information on the interaction of defined groups with each other.
- Blackburn, G. Michael,Kent, Hilary E.,Lilley, Terence H.
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- Cobalt-Catalyzed Deprotection of Allyl Carboxylic Esters Induced by Hydrogen Atom Transfer
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A brief, efficient method has been developed for the removal of the allyl protecting group from allyl carboxylic esters using a Co(II)/TBHP/(Me2SiH)2O catalytic system. This facile strategy displays excellent chemoselectivity, functional group tolerance, and high yields. This transformation probably occurs through the hydrogen atom transfer process, and a Co(III)-six-membered cyclic intermediate is recommended.
- Li, Nan,Gui, Yizhen,Chu, Mengqi,You, Mengdi,Qiu, Xiaohan,Liu, Hejia,Wang, Shiang,Deng, Meng,Ji, Baoming
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supporting information
p. 8460 - 8464
(2021/11/13)
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- Design and synthesis of tripeptidyl furylketones as selective inhibitors against the β5 subunit of human 20S proteasome
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A series of tripeptidic proteasome inhibitors with furylketone as C-terminus were designed and synthesized. Biochemical evaluations against β1, β2 and β5 subunits revealed that they acted selectively on β5 subunit with IC50s against chymotrypsin-like (CT-L) activity in micromolar range. LC-MS/MS analysis of the ligand-20S proteasome mixture showed that the most potent compound 11m (IC50 = 0.18 μM) made no covalent modification on 20S proteasome. However, it was identified acting in a slowly reversible manner in wash-out assay and the reversibility was much lower than that of MG132, suggesting the possibility of these tripeptidic furylketones forming reversible covalent bonds with 20S proteasome. Several compounds were selected for anti-proliferative assay towards multiple cancer cell lines, and compound 11m displayed comparable potency to positive control (MG132) in all cell lines tested. Furthermore, the pharmacokinetic (PK) data in rats indicated 11m behaved similarly (Cmax, 2007 μg/L; AUC0?t, 680 μg/L·h; Vss, 0.66 L/kg) to the clinical used agent carfilzomib. All these data suggest 11m is a good lead compound to be developed to novel anti-tumor agent.
- Lü, Zirui,Li, Xiaona,Niu, Yan,Sun, Qi,Wang, Chao,Xi, Dandan,Xu, Fengrong,Xu, Ping,Zhou, Tongliang
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- A Next-Generation Air-Stable Palladium(I) Dimer Enables Olefin Migration and Selective C?C Coupling in Air
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We report a new air-stable PdI dimer, [Pd(μ-I)(PCy2tBu)]2, which triggers E-selective olefin migration to enamides and styrene derivatives in the presence of multiple functional groups and with complete tolerance of air. The same dimer also triggers extremely rapid C?C coupling (alkylation and arylation) at room temperature in a modular and triply selective fashion of aromatic C?Br, C?OTf/OFs, and C?Cl bonds in poly(pseudo)halogenated arenes, displaying superior activity over previous PdI dimer generations for substrates that bear substituents ortho to C?OTf.
- Kundu, Gourab,Rissanen, Kari,Schoenebeck, Franziska,Sperger, Theresa
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p. 21930 - 21934
(2020/10/02)
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- Enantioselective inclusion of pyrene-1-sulfonate salts of α-amino acids with crystals of α-cyclodextrin
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Enantioselective inclusion of α-amino acids with crystals of α-cyclodextrin (α-CD) has been achieved by converting the amino acids into sulfonate salts with pyrene-1-sulfonic acid (PyS). For example, crystals of α-CD selectively include L-leucine/PyS (1:1) salt in a host/guest ratio of ~1 with 92%ee from a solution of the racemic salt in ethanol/N-methylformamide (91:9) at 40 °C. Under conditions optimized for individual amino acids, the PyS salts of valine, phenylalanine, and methionine are also included with good enantioselectivities (up to 86%ee). Mechanistic studies for the inclusion of leucine/PyS salt reveals that the enantioselectivity originates from the difference in stability between the inclusion complexes of D- and L-leucine/PyS salts with α-CD in crystals.
- Hattori, Tetsutaro,Kitamoto, Yuichi,Maeda, Tetsuya,Miyoshi, Ikuko,Morohashi, Naoya
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- α-Amino Diphenyl Phosphonates as Novel Inhibitors of Escherichia coli ClpP Protease
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Increased Gram-negative bacteria resistance to antibiotics is becoming a global problem, and new classes of antibiotics with novel mechanisms of action are required. The caseinolytic protease subunit P (ClpP) is a serine protease conserved among bacteria that is considered as an interesting drug target. ClpP function is involved in protein turnover and homeostasis, stress response, and virulence among other processes. The focus of this study was to identify new inhibitors of Escherichia coli ClpP and to understand their mode of action. A focused library of serine protease inhibitors based on diaryl phosphonate warheads was tested for ClpP inhibition, and a chemical exploration around the hit compounds was conducted. Altogether, 14 new potent inhibitors of E. coli ClpP were identified. Compounds 85 and 92 emerged as most interesting compounds from this study due to their potency and, respectively, to its moderate but consistent antibacterial properties as well as the favorable cytotoxicity profile.
- Moreno-Cinos, Carlos,Sassetti, Elisa,Salado, Irene G.,Witt, Gesa,Benramdane, Siham,Reinhardt, Laura,Cruz, Cristina D.,Joossens, Jurgen,Van Der Veken, Pieter,Br?tz-Oesterhelt, Heike,Tammela, P?ivi,Winterhalter, Mathias,Gribbon, Philip,Windshügel, Bj?rn,Augustyns, Koen
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p. 774 - 797
(2019/01/30)
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- Synthesis and biological activity of peptide proline-boronic acids as proteasome inhibitors
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On the basis of the application of proline-boronic acid as pharmacophore in the kinase inhibitors and our previous research results, using proline-boronic acid as warhead, two series of peptide proline-boronic acids, dipeptide proline-boronic acids (I) and tripeptide proline-boronic acids (II), were designed and synthesized. All the synthesized compounds were first evaluated for their biological activity against MGC803 cell, and then, the best compound II-7 was selected to test its anti-tumor spectrum on six human tumor cell lines and proteasome inhibition against three subunits. The results indicated that series II have much better biological activities than series I. The compound II-7 exhibited not only excellent biological activities with IC50 values of nM level in both cell and proteasome models, but also much better subunit selectivity. Thus, proline-boronic acid as warhead is reasonable in the design of proteasome inhibitors.
- Han, Liqiang,Wen, Yanzhao,Li, Ridong,Xu, Bo,Ge, Zemei,Wang, Xin,Cheng, Tieming,Cui, Jingrong,Li, Runtao
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p. 4031 - 4044
(2017/07/05)
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- Synthesis and evaluation of chirally defined side chain variants of 7-chloro-4-aminoquinoline to overcome drug resistance in malaria chemotherapy
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A novel 4-aminoquinoline derivative [(S)-7-chloro-N-(4-methyl-1-(4-methyl-piperazin-1-yl)pentan-2-yl)-quinolin-4-amine triphosphate] exhibiting curative activity against chloroquine-resistant malaria parasites has been identified for preclinical development as a blood schizonticidal agent. The lead molecule selected after detailed structure-activity relationship (SAR) studies has good solid-state properties and promising activity against in vitro and in vivo experimental malaria models. The in vitro absorption, distribution, metabolism, and excretion (ADME) parameters indicate a favorable drug-like profile.
- Dola, Vasantha Rao,Soni, Awakash,Agarwal, Pooja,Ahmad, Hafsa,Raju, Kanumuri Siva Rama,Rashid, Mamunur,Wahajuddin, Muhammad,Srivastava, Kumkum,Haq,Dwivedi,Puri,Katti
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- A kind of amino acid tanshinone phenolic derivative and its preparation method
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The invention relates to amino acid tanshinone phenolic ester derivatives and a preparation method thereof. The derivatives are obtained by reducing tanshinone compounds and performing esterified modification on the reduced tanshinone compounds and an amino acid into prodrugs, wherein the tanshinone compounds are phenanthrenequinone compounds which exist in salvia miltiorrhiza and have an o-quinone structure; the esterified amino acid is alpha-amino acid. The amino acid tanshinone phenolic ester derivatives are compounds having a structure of a general formula (I) or medicinal salts thereof, wherein R1 and R2 represent H or acyl alpha-amino acid and a salt thereof, and R1 and R2 are not H at the same time. The amino acid tanshinone phenolic ester derivatives have the beneficial effects that firstly, the new tanshinone derivatives are provided and the new substances have potential treatment effect on some serious diseases such as tumors, and secondly, amino acid tanshinone phenolic ester derivatives have excellent water solubility and thus can be prepared into injections conveniently in addition to various oral preparations, and therefore, the amino acid tanshinone phenolic ester derivatives are capable of quickly taking effect in disease treatment. As important prodrugs, the amino acid tanshinone phenolic ester derivatives have important application value.
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Paragraph 0075
(2016/10/09)
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- LAT1 activity of carboxylic acid bioisosteres: Evaluation of hydroxamic acids as substrates
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Large neutral amino acid transporter 1 (LAT1) is a solute carrier protein located primarily in the blood–brain barrier (BBB) that offers the potential to deliver drugs to the brain. It is also up-regulated in cancer cells, as part of a tumor's increased metabolic demands. Previously, amino acid prodrugs have been shown to be transported by LAT1. Carboxylic acid bioisosteres may afford prodrugs with an altered physicochemical and pharmacokinetic profile than those derived from natural amino acids, allowing for higher brain or tumor levels of drug and/or lower toxicity. The effect of replacing phenylalanine's carboxylic acid with a tetrazole, acylsulfonamide and hydroxamic acid (HA) bioisostere was examined. Compounds were tested for their ability to be LAT1 substrates using both cis-inhibition and trans-stimulation cell assays. As HA-Phe demonstrated weak substrate activity, its structure–activity relationship (SAR) was further explored by synthesis and testing of HA derivatives of other LAT1 amino acid substrates (i.e., Tyr, Leu, Ile, and Met). The potential for a false positive in the trans-stimulation assay caused by parent amino acid was evaluated by conducting compound stability experiments for both HA-Leu and the corresponding methyl ester derivative. We concluded that HA's are transported by LAT1. In addition, our results lend support to a recent account that amino acid esters are LAT1 substrates, and that hydrogen bonding may be as important as charge for interaction with the transporter binding site.
- Zur, Arik A.,Chien, Huan-Chieh,Augustyn, Evan,Flint, Andrew,Heeren, Nathan,Finke, Karissa,Hernandez, Christopher,Hansen, Logan,Miller, Sydney,Lin, Lawrence,Giacomini, Kathleen M.,Colas, Claire,Schlessinger, Avner,Thomas, Allen A.
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supporting information
p. 5000 - 5006
(2016/10/05)
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- Amidase activity of phosphonate TSA-built polymer catalysts derived from organic monomers in the amidolysis of amino acid p-nitroanilides
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Highly crosslinked transition state analogue imprinted macromatric polymer catalysts having imidazole, carboxyl and hydroxyl functional groups in the catalytic sites were synthesized as chymotrypsin mimics using achiral organic monomers 4-vinylimidazole, methacrylic acid, allyl alcohol and phenyl-1-(N-benzyloxycarbonylamino)-2-(phenyl)ethyl phosphonate (transition state analogue of ester and amide hydrolytic reactions) as the template. The catalytic properties of the enzyme mimics were investigated in the amidolytic reactions of L-amino acid p-nitroanilides and correlated to the amidase activities of the catalysts derived from chiral methacryloyl-L-amino acid monomers methacryloyl-L-histidine, methacryloyl-L-aspartic acid and methacryloyl-L-serine. A two-fold enhancement in rate acceleration, substrate specificity, substrate shape-selectivity and stereoselectivity was observed for polymers made up of flexible amino acid monomers compared to the copolymers of organic monomers. The pre-polymerization complex of TSA with methacryloyl-L-amino acid monomers fabricates specific 3D-memory cavity preferentially of L-enantiomer of the TSA in the polymer matrix while the achiral organic monomers designs both L- and D- cavities The effect of crosslink density on the catalytic efficiencies of the polymer catalysts was also investigated. Replacement of allyl alcohol by vinylpyridine afforded catalyst with better enzymatic activity.
- Mathew, Divya,Thomas, Benny,Devaky
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- COMPOUNDS USEFUL AS CSF1 MODULATORS
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This invention relates to novel compounds and to pharmaceutical compositions comprising the novel compounds. More specifically, the invention relates to compounds useful as Colony Stimulating Factor 1 Receptor (cFMS) modulators (e.g. cFMS inhibitors). This invention also relates to processes for preparing the compounds, uses of the compounds in treatment and methods of treatment employing the compounds. Specifically, the invention relates to the use of the compounds for the treatment of cancer and autoimmune diseases.
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Paragraph 00436; 00437
(2016/04/26)
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- Amidase activity of phosphonate analogue imprinted chymotrypsin mimics in shape-selective, substrate-specific and enantioselective amidolysis of l-phenylalanine-p-nitroanilides
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Focusing on chymotrypsin mimics, highly crosslinked enzyme mimics are synthesized by molecular imprinting technique for the amidolysis of p-nitroanilide of phenylalanine, using phenyl-1-(N-benzyloxycarbonylamino)-2-(phenyl)ethyl phosphonate - the transition state analog of amidolysis - as the template, N-methacryloyl-l-histidine, N-methacryloyl-l-aspartic acid, and N-methacryloyl-l-serine as the functional monomers and EGDMA as the crosslinking agent. The amidase activity of the enzyme mimics follows pseudo first order kinetics. The transition state analog provides a tetrahedral geometry complementary to the transition state intermediate, which is responsible for the catalytic activity of the imprinted enzyme mimics. The enzyme mimics show stereospecificity and substrate selectivity in the amidolysis of phenylalanine p-nitroanilide. The proper orientation of the reactive functionalities in the super crosslinked macroporous polymer matrix for selective binding of the substrate through H-bonding is responsible for the high imprinting efficiency and substrate specificity of the imprinted polymer catalysts. Low cost, ease of preparation, high thermal stability, reusability and higher shelf life make the polymer catalysts better chymotrypsin mimics.
- Mathew, Divya,Thomas, Benny,Devaky
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- Development of novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation
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Novel dipeptide-like rhodesain inhibitors containing the 3-bromoisoxazoline warhead in a constrained conformation were developed; some of them possess Ki values in the micromolar range. We studied the structure-activity relationship of these derivatives and we performed docking studies, which allowed us to find out the key interactions established by the inhibitors with the target enzyme. Biological results indicate that the nature of the P2 and P3 substituents and their binding to the S2/S3 pockets is strictly interdependent.
- Ettari, Roberta,Pinto, Andrea,Previti, Santo,Tamborini, Lucia,Angelo, Ilenia C.,La Pietra, Valeria,Marinelli, Luciana,Novellino, Ettore,Schirmeister, Tanja,Zappalà, Maria,Grasso, Silvana,De Micheli, Carlo,Conti, Paola
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p. 7053 - 7060
(2015/11/11)
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- METHOD FOR PRODUCING CARBOXYLIC ACID AND ALCOHOL BY HYDROLYSIS OF ESTER
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As shown by the following formula (1), after methyl laurate (2 mmol) and water (8 mL) are added to an ammonium pyrosulfate catalyst (5 mol%), a hydrolysis reaction of methyl laurate is carried out by heating for 24 hours at 60°C while stirring is performed, so that lauric acid can be obtained with a yield of 86%.
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Paragraph 0069; 0070
(2014/11/13)
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- Synthesis of enantiopure free and N-benzyloxycarbonyl-protected 3-substituted homotaurines from naturally occurring amino acids
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Enantiopure N-benzyloxycarbonyl-protected and free 3-substituted homotaurines were synthesized from naturally occurring amino acids via N-benzyloxycarbonyl protection, Arndt-Eistert homologation, reduction, esterification with thioacetic acid, and oxidation with performic acid. The current method is a convenient, practical, and salt-free method for the synthesis of enantiopure 3-substituted homotaurine with moderate to good yields.
- Zheng, Yongpeng,Xu, Jiaxi
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p. 5197 - 5206
(2014/12/10)
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- Kinetically controlled peptide synthesis mediated by papain using the carbamoylmethyl ester as an acyl donor
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A series of dipeptides were synthesized generally in good yields with carbamoylmethyl (Cam) esters as acyl donors in the presence of a cysteine protease, papain, immobilized on Celite. Several segment condensations were also achieved generally in high yields without danger of racemization and formation of the secondary-hydrolysis product. Moreover, partial sequences of some bioactive peptides were prepared through segment condensations, and aimed-at peptides were obtained generally in high yields without the racemization of C-terminal residues of the carboxyl components. Thus, the superiority of the Cam ester in the kinetically controlled peptide synthesis was once again ascertained in couplings mediated by the cysteine protease as in those catalyzed by the serine proteases reported earlier.
- Miyazawa, Toshifumi,Horimoto, Takao,Tanaka, Kayoko
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p. 371 - 376
(2014/08/18)
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- Inhibition of norovirus 3CL protease by bisulfite adducts of transition state inhibitors
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Noroviruses are the most common cause of acute viral gastroenteritis, accounting for >21 million cases annually in the US alone. Norovirus infections constitute an important health problem for which there are no specific antiviral therapeutics or vaccines. In this study, a series of bisulfite adducts derived from representative transition state inhibitors (dipeptidyl aldehydes and α-ketoamides) was synthesized and shown to exhibit anti-norovirus activity in a cell-based replicon system. The ED 50 of the most effective inhibitor was 60 nM. This study demonstrates for the first time the utilization of bisulfite adducts of transition state inhibitors in the inhibition of norovirus 3C-like protease in vitro and in a cell-based replicon system. The approach described herein can be extended to the synthesis of the bisulfite adducts of other classes of transition state inhibitors of serine and cysteine proteases, such as α-ketoheterocycles and α-ketoesters.
- Mandadapu, Sivakoteswara Rao,Gunnam, Mallikarjuna Reddy,Tiew, Kok-Chuan,Uy, Roxanne Adeline Z.,Prior, Allan M.,Alliston, Kevin R.,Hua, Duy H.,Kim, Yunjeong,Chang, Kyeong-Ok,Groutas, William C.
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- Design, synthesis, and biological evaluation of novel dipeptide-type SARS-CoV 3CL protease inhibitors: Structure-activity relationship study
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This work describes the design, synthesis, and evaluation of low-molecular weight peptidic SARS-CoV 3CL protease inhibitors. The inhibitors were designed based on the potent tripeptidic Z-Val-Leu-Ala(-pyrrolidone-3-yl)-2-benzothiazole (8; Ki = 4.1 nM), in which the P3 valine unit was substituted with a variety of distinct moieties. The resulting series of dipeptide-type inhibitors displayed moderate to good inhibitory activities against 3CLpro. In particular, compounds 26m and 26n exhibited good inhibitory activities with Ki values of 0.39 and 0.33 μM, respectively. These low-molecular weight compounds are attractive leads for the further development of potent peptidomimetic inhibitors with pharmaceutical profiles. Docking studies were performed to model the binding interaction of the compound 26m with the SARS-CoV 3CL protease. The preliminary SAR study of the peptidomimetic compounds with potent inhibitory activities revealed several structural features that boosted the inhibitory activity: (i) a benzothiazole warhead at the S1′ position, (ii) a γ-lactam unit at the S1-position, (iii) an appropriately hydrophobic leucine moiety at the S2-position, and (iv) a hydrogen bond between the N-arylglycine unit and a backbone hydrogen bond donor at the S3-position.
- Thanigaimalai, Pillaiyar,Konno, Sho,Yamamoto, Takehito,Koiwai, Yuji,Taguchi, Akihiro,Takayama, Kentaro,Yakushiji, Fumika,Akaji, Kenichi,Kiso, Yoshiaki,Kawasaki, Yuko,Chen, Shen-En,Naser-Tavakolian, Aurash,Sch?n, Arne,Freire, Ernesto,Hayashi, Yoshio
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p. 436 - 447
(2013/10/01)
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- Glycosylation mediated - BAIL in aqueous solution
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The use of Br?nsted acid ionic liquid (BAIL) as a catalyst for the activation of unreactive and unprotected glycosyl donors has been demonstrated for the first time in aqueous solution.
- Delacroix, Sébastien,Bonnet, Jean-Pierre,Courty, Matthieu,Postel, Denis,Van Nhien, Albert Nguyen
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- Photorelease of amino acids from novel thioxobenzo[f]benzopyran ester conjugates
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Aiming at the enhancement of the performance of (9-methoxy-3-oxo-3H- benzo[f]benzopyran-1-yl) methyl ester as photocleavable protecting group for the carboxylic acid function at long-wavelengths, 9-methoxy-3-thioxo-3H-benzo[f] benzopyran-l-valine and l-phenylalanine model conjugates were prepared through a thionation reaction of the corresponding oxo-benzobenzopyrans. These thioxobenzobenzopyran derivatives were subjected to photocleavage reactions in the same conditions as the parent oxo-benzobenzopyrans at different wavelengths of irradiation, and photocleavage data were obtained. It was found that the exchange of the carbonyl by a thiocarbonyl group enhanced the performance of the heterocyclic protecting group at 419 nm by improving the photolysis rates, making it an appropriate group for practical applications at long wavelengths.
- Piloto, Ana M.,Soares, Ana M. S.,Costa, Susana P. G.,Goncalves, M. Sameiro T.
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experimental part
p. 2275 - 2282
(2012/08/29)
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- N,N-diarylammonium pyrosulfate as a highly effective reverse micelle-type catalyst for hydrolysis of esters
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Reverse micelle-type N,N-diarylammonium pyrosulfate (3-5 mol %) efficiently catalyzes the hydrolysis of esters (up to 100 mmol scale) under organic solvent-free conditions. The present method is successfully applied to the hydrolysis of various esters without the decomposition of the base-sensitive moieties and without any loss of optical purity for α-heterosubstituted carboxylic acids.
- Koshikari, Yoshiki,Sakakura, Akira,Ishihara, Kazuaki
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supporting information; scheme or table
p. 3194 - 3197
(2012/07/31)
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- A mild method for the cleavage of the 4-picolyloxy group with magnesium under neutral conditions
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A mild and efficient method for the selective hydrolysis of 4-picolyl esters with magnesium in methanol or water in the presence of other esters and sensitive protecting groups is described. 4-Picolyl aryl ethers and thioethers are also smoothly deprotected to give the corresponding phenols and thiophenols. Georg Thieme Verlag Stuttgart. New York.
- Zhu, Jianwei,Miao, Wenjun,Bao, Lingling,Ji, Tao,Tang, Guo,Xu, Pengxiang,Zhao, Yufen
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supporting information; experimental part
p. 142 - 144
(2012/02/04)
-
- Toward the selective delivery of chemotherapeutics into tumor cells by targeting peptide transporters: Tailored gold-based anticancer peptidomimetics
-
Complexes [AuIIIX2(dtc-Sar-AA-O(t-Bu))] (AA = Gly, X = Br (1)/Cl (2); AA = Aib, X = Br (3)/Cl (4); AA = l-Phe, X = Br (5)/Cl (6)) were designed on purpose in order to obtain gold(III)-based anticancer peptidomimetics that might specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy, and the crystal structure of [AuIIIBr2(dtc-Sar-Aib-O(t- Bu))] (3) was solved and refined. According to in vitro cytotoxicity studies, the Aib-containing complexes 3 and 4 turned out to be the most effective toward all the human tumor cell lines evaluated (PC3, DU145, 2008, C13, and L540), reporting IC50 values much lower than that of cisplatin. Remarkably, they showed no cross-resistance with cisplatin itself and were proved to inhibit tumor cell proliferation by inducing either apoptosis or late apoptosis/necrosis depending on the cell lines. Biological results are here reported and discussed in terms of the structure-activity relationship.
- Negom Kouodom, Morelle,Ronconi, Luca,Celegato, Marta,Nardon, Chiara,Marchiò, Luciano,Dou, Q. Ping,Aldinucci, Donatella,Formaggio, Fernando,Fregona, Dolores
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supporting information; scheme or table
p. 2212 - 2226
(2012/05/05)
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- Long-wavelength photolysis of amino acid 6-(methoxy-2-oxo-2H-naphtho[1,2-b] pyran-4-yl)methyl esters
-
(6-Methoxy-2-oxo-2H-naphtho[1,2-b]pyran-4-yl)methyl esters of valine or phenylalanine as model bifunctional molecules were synthesised to assess its applicability as a photocleavable protecting group for solution phase organic synthesis and in caging applications at longer wavelengths. The behaviour of the corresponding derivatives towards photolysis was evaluated by irradiation at 350 and 419 nm in a mixture of HEPES buffer and acetonitrile or methanol in a photochemical reactor, followed by HPLC/UV monitoring. Time-resolved fluorescence measurements were used to elucidate the dynamics. Photocleavage studies of new valine orphenylalanine 2H-naphtho[1,2-b]pyran-4-yl)methyl esters revealed that the amino acid-heterocycle ester bond was efficiently photolysed, especially at 419 nm for all compounds in practical irradiation times. Copyright
- Piloto, Ana M.,Soares, Ana M. S.,Hungerford, Graham,Costa, Susana P. G.,Goncalves, M. Sameiro T.
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experimental part
p. 5447 - 5451
(2011/12/02)
-
- Design, synthesis, and antitumor activity of 4-halocolchicines and their pro-drugs activated by cathepsin B
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Novel colchicine derivatives possessing various substituents at the C4 position were prepared. Among them, 4-halo derivatives 3-6 were found to exhibit higher activity against cancer cell lines (A549, HT29, HCT116) as well as on mice transplanted with the HCT116 human colorectal carcinoma cell line than colchicine (1). Further, utilizing the 4-substituted colchicines, we prepared pro-drugs having a dipeptide side chain and demonstrated that these pro-drugs were activated by cathepsin B, an enzyme overexpressed in tumor cells, and exhibited selective toxicity to the tumor cells.
- Yasobu, Naoko,Kitajima, Mariko,Kogure, Noriyuki,Shishido, Yoshiyuki,Matsuzaki, Takeshi,Nagaoka, Masato,Takayama, Hiromitsu
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scheme or table
p. 348 - 352
(2011/07/09)
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- An improved large scale procedure for the preparation of N-Cbz amino acids
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A simple and scalable method for the preparation of N-Cbz protected amino acids is presented which uses a mixture of aqueous sodium carbonate and sodium bicarbonate to maintain the appropriate pH during the addition of benzyl chloroformate. The method has been extended to other N-protections and is amenable to large scale preparation of an intermediate toward Zofenopril, an ACE inhibitor.
- Pehere, Ashok D.,Abell, Andrew D.
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experimental part
p. 1493 - 1494
(2011/05/16)
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- Exceptionally small supramolecular hydrogelators based on aromatic-aromatic interactions
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We report herein the use of an aromatic-aromatic interaction to produce small molecule hydrogelators that self-assemble in water and form molecular nanofibers in the resulting hydrogels. Among these hydrogelators, a hydrogelator (6) made from a phenyl-alanine and a cinnamoyl group represents the lowest molecular weight (MW = 295.33 g/mol) peptide-based hydrogelator prepared to date. The supramolecular hydrogels were characterized by transmission electron micrograph (TEM) and fluorescence spec-troscopy, and the results obtained by both techniques correlate well with their rheological properties. Notably, compound 6 can undergo cis/trans-isomerization upon UV irradiation.
- Shi, Junfeng,Gao, Yuan,Yang, Zhimou,Xu, Bing
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supporting information; experimental part
p. 167 - 172
(2011/05/19)
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- Papain-catalyzed peptide bond formation: Enzyme-specific activation with guanidinophenyl esters
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The substrate mimetics approach is a versatile method for small-scale enzymatic peptide-bond synthesis in aqueous systems. The protease-recognized amino acid side chain is incorporated in an ester leaving group, the substrate mimetic. This shift of the specific moiety enables the acceptance of amino acids and peptide sequences that are normally not recognized by the enzyme. The guanidinophenyl group (OGp), a known substrate mimetic for the serine proteases trypsin and chymotrypsin, has now been applied for the first time in combination with papain, a cheap and commercially available cysteine protease. To provide insight in the binding mode of various Z-XAA-OGp esters, computational docking studies were performed. The results strongly point at enzyme-specific activation of the OGp esters in papain through a novel mode of action, rather than their functioning as mimetics. Furthermore, the scope of a model dipeptide synthesis was investigated with respect to both the amino acid donor and the nucleophile. Molecular dynamics simulations were carried out to prioritize 22 natural and unnatural amino acid donors for synthesis. Experimental results correlate well with the predicted ranking and show that nearly all amino acids are accepted by papain.
- de Beer, Roseri J.A.C.,Zarzycka, Barbara,Amatdjais-Groenen, Helene I.V.,Jans, Sander C.B.,Nuijens, Timo,Quaedflieg, Peter J.L.M.,van Delft, Floris L.,Nabuurs, Sander B.,Rutjes, Floris P.J.T.
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experimental part
p. 2201 - 2207
(2012/05/05)
-
- Addition of allylzinc to a-amino acid-derived imines: Synthesis of diamino alcohols by Hydroboration
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Imines obtained by condensation of Z-pro- tected or Boc-protected α-amino aldehydes with α-amino tert-butyl esters or with O-silyl-protected amino alcohols were reacted with preformed allyl zinc yielding homoal- lylamines with yields around 50% and selectivities ranging from 50:50 to 90:10. Hydroboration of the terminal double bond furnished diamino alcohols with yields up to 97%. The configuration of the substrates was determined by X-ray-crystallographic analysis of a hydroboration product and comparison of physical data. Springer-Verlag 2010.
- Virlouvet, Mickael,Goesmann, Helmut,Feldmann, Claus,Podlech, Joachim
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scheme or table
p. 177 - 198
(2010/08/05)
-
- AmIno Acid Homologation by the Blaise Reaction: A new entry into nitrogen heterocycles
-
(Chemical Equation Presented) A general strategy for the amino acid homologation via Blaise reaction and subsequent reduction is presented. This strategy involves the preparation of protected α-amino nitriles from the corresponding amino acids, followed by the zinc-mediated condensation of tert-butyl bromoacetate, to give the imidazolidones after iminozincate cyclization. Reduction gave the saturated imidazolidinones with cis or trans stereochemistry, depending on the reduction conditions. This strategy was applied to nonfunctionalized amino acids and to functionalized amino acids such as serine and aspartic acid. Additionally, acidic hydrolysis of cis or trans imidazolidinones to the corresponding chiral 4-aminopyrrolidones is described.
- Cam, Thuy Hoang,Bouillere, Francelin,Johannesen, Sine,Zulauf, Anais,Panel, Cecilia,Pouilhes, Annie,Gori, Didier,Alezra, Valerie,Kouklovsky, Cyrille
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scheme or table
p. 4177 - 4187
(2009/09/08)
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- Expedient solid-phase synthesis of both symmetric and asymmetric diol libraries targeting aspartic proteases
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C2-symmetric diols have been shown to be highly potent against HIV-1 protease (PR). However, gaining access to these compounds has been hampered by the need of multistep solution-phase reactions which are often tedious and inefficient. In this Letter, we have disclosed a solid-phase strategy for rapid preparation of small molecule-based, symmetric and asymmetric diols as potential HIV-1 protease inhibitors. Upon biological screening, we found one of them, SYM-5, to be a potent and selective inhibitor (Ki = 400 nM) against HIV-1 protease.
- Shi, Haibin,Liu, Kai,Leong, Wendy W.Y.,Yao, Shao Q.
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supporting information; experimental part
p. 3945 - 3948
(2010/03/30)
-
- Oxoammonium salt/NaClO2: An expedient, catalytic system for one-pot oxidation of primary alcohols to carboxylic acids with broad substrate applicability
-
A facile, green, one-pot oxidation of primary alcohols to carboxylic acids with broad substrate applicability has been developed by employing an expedient catalytic system consisting of 1-Me-AZADO+X-/NaClO 2. The Royal Society of Chemistry.
- Shibuya, Masatoshi,Sato, Takahisa,Tomizawa, Masaki,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 1739 - 1741
(2009/08/08)
-
- Synthesis, self-assembling properties, and atom transfer radical polymerization of an alkylated L-phenylalanine-derived monomeric organogel from silica: A new approach to prepare packing materials for high-performance liquid chromatography
-
The monomer N′-octadecylNα-(4-vinyl)-benzoyl-L- phenylalanineamide (4) based on L-phenylalanine has been simply but effectively synthesized, and its self-assembling properties have been investigated. FTIR and a variable-temperature 1H NMR spectroscopic investigation demonstrated that the aggregation of compound 4 in various organic solvents is due to the formation of intermolecular hydrogen bonds among the amide moieties. UV/Vis measurements indicated that the multiple π-π interactions of the phenyl groups also contribute to the self-as-sembly. As was observed by 13C cross-polarization magic-angle spinning (CP/MAS) NMR and variable-temperature 1H NMR measurements, the ordered alkyl chains also played an important role in the molecular aggregation by van der Waals interactions. Compound 4 was polymerized by surface-initiated atom transfer radical polymerization from porous silica gel to prepare a packing material for HPLC. The results of thermogravimetric analysis showed that a relatively large amount of polymer was grafted onto the silica surface. The organic phase on silica was in a noncrystalline solid form in which the long alkyl chain exists in a less-ordered gauche conformation. Analysis of chromatographic performance for polyaromatic hydrocarbon samples showed higher selectivity than conventional reversed-phase HPLC packing materials.
- Rahman, M. Mizanur,Czaun, Miklos,Takafuji, Makoto,Ihara, Hirotaka
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p. 1312 - 1321
(2008/09/17)
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- (1-Nosyl-5-nitroindol-3-yl)methyl ester: A novel protective group for carboxylic acids
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(Chemical Equation Presented) The usefulness of (1-nosyl-5-nitroindol-3-yl) methyl esters as a novel protective group for carboxylic acid is fully demonstrated. The novel protective group is stable under a broad range of conditions and can easily be deprotected under the mild conditions used for removal of the nosyl (Ns) group. It is orthogonal to the existing protective groups for carboxylic acids such as t-butyl and allyl esters.
- Nishimura, Takuya,Yamada, Kouhei,Takebe, Tohru,Yokoshima, Satoshi,Fukuyama, Tohru
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supporting information; experimental part
p. 2601 - 2604
(2009/05/26)
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- Azadipeptide nitriles: Highly potent and proteolytically stable inhibitors of papain-like cysteine proteases
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(Chemical Presented) Nitrogen instead of carbon: Azadipeptide nitriles resulting from CH/N exchange in the P1 position (see picture) are hitherto unknown. To access these compounds by conversion of amino acid-derived hydrazides with cyanogen bromide both nitrogen atoms of the hydrazide must be substituted. Despite a methylated P2-P1 peptide bond, the azadipeptide nitriles show a strong inhibitory activity against cysteine proteases, and a high stability towards chymotryptic hydrolysis.
- Loeser, Reik,Frizler, Maxim,Schilling, Klaus,Guetschow, Michael
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supporting information; experimental part
p. 4331 - 4334
(2009/02/08)
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- Modified amino acids
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The present invention provides a compound of the general formula 1, wherein X is the connection between the CO-hydrazine and the NR1-oxalic acid or ester group, and uses and synthesis methods. These compounds represent amino acid derivatives, wherein the amine group is turned into an acidic group by the oxalic acid group and the carboxylic acid is turned into an amine functionality by the hydrazine group; as well as peptidomimetics comprising the compound and methods for their synthesis.
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-
Page/Page column 10-11
(2008/06/13)
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- Pd-catalyzed enantioselective synthesis of quaternary α-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide
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A Pd-catalyzed enantioselective synthesis of quaternary α-amino acid derivatives using a phenylalanine-derived P-chirogenic diaminophosphine oxide is described. Asymmetric allylic substitution using acyclic β-keto esters with a nitrogen functional group at the α-carbon as prochiral nucleophiles proceeded in the presence of 5 mol % of Pd catalyst, 10 mol % of chiral diaminophosphine oxide 1j, BSA, and appropriate additives, affording the corresponding quaternary α-amino acid derivatives in excellent yield and in up to 92% ee.
- Nemoto, Tetsuhiro,Harada, Teisuke,Matsumoto, Takayoshi,Hamada, Yasumasa
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p. 6304 - 6307
(2008/02/10)
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- A Stereoselective entry into functionalized 1,2-diamines by zinc-mediated homologation of α-aminoacids
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A general, stereoselective synthsis of 4,5-disubstituted imidazolidines-2-ones from α-aminoacids has been developed: the key steps are a Biaise reaction of bromoacetate on α-aminonitriles and further reduction. Although reduction with sodium cyanoborohydride afforded a mixture of cis and trans isomers 6a-e with moderate to good stereoselectivity, reduction with sodium in liquid ammonia gave the trans isomers 8a-e with complete stereoselectivity. Acidic hydrolysis of the urea gave 4-amino-pyrrolidinones, which can be precursors to β,γ-diaminoacids or 3-aminopyrrolidines.
- Hoang, Cam Thuy,Alezra, Valerie,Guillot, Regis,Kouklovsky, Cyrille
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p. 2521 - 2524
(2008/02/05)
-
- Iridium(I)-catalyzed stereospecific decarboxylative allylic amidation of chiral branched benzyl allyl imidodicarboxylates
-
(Chemical Equation Presented) Ir(I)-catalyzed decarboxylase allylic amidation of chiral branched benzyl allyl imidodicarboxylates has been shown to proceed with complete retention of enantiomeric purity and configuration. The transformation is stereospecific and appears to be quite general, accommodating a wide range of R groups.
- Singh, Om V.,Han, Hyunsoo
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p. 4801 - 4804
(2008/03/15)
-
- Scope and limitations of sodium and potassium trimethylsilanolate as reagents for conversion of esters to carboxylic acids
-
Sodium or potassium trimethylsilanolate act as versatile and very powerful reagents for conversion of a wide variety of esters to carboxylic acids. The reactions were performed in tetrahydrofuran under mild reaction conditions with high to quantitative yields.
- Lovric, Marija,Cepanec, Ivica,Litvic, Mladen,Bartolincic, Anamarija,Vinkovic, Vladimir
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p. 109 - 115
(2008/02/04)
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- α-Chymotrypsin-catalyzed peptide synthesis in frozen aqueous solution using N-protected amino acid carbamoylmethyl esters as acyl donors
-
A kinetically controlled peptide synthesis catalyzed by α-chymotrypsin was performed in frozen aqueous solution (ice, -24 °C). The yield of the peptide was significantly improved by the use of the carbamoylmethyl (Cam) ester as the acyl donor instead of the conventional ethyl ester. The peptide yield increased up to ca. 90% when N-benzyloxycarbonyl (CBZ)-Phe-OCam and H-Phe-NH2 were used as the acyl donor and nucleophile, respectively. Such an improvement of the peptide yield in ice was also observed in the coupling of other CBZ-amino acid Cam esters as acyl donors. Furthermore, this approach was applied to the synthesis of peptides containing d-amino acids. The peptides such as CBZ-d-Phe-Phe-NH2, CBZ-Phe-d-Phe-NH2 and CBZ-d-Phe-d-Phe-NH2 were also obtained in excellent to moderate yields in ice. A high diastereoselectivity towards the l-l peptide was observed when the racemic amino acid Cam ester was used as the acyl donor in ice.
- Salam, Sayed Mohiuddin Abdus,Kagawa, Ken-Ichi,Kawashiro, Katsuhiro
-
-
- FLUOROUS OXAZOLIDINONE CHIRAL AUXILIARY COMPOUNDS AND METHODS OF MANUFACTURE
-
The present invention relates generally to perfluoroalkyl chiral auxiliary compounds and methods of manufacture. These compounds have the functionality to effectively support the synthesis of chiral compounds in single reactions, high-throughput parallel recations, or combinatorial reactions The invention relates to two oxazolidmone chiral auxiliaries (1) and (2): wherein Rf is a perfluoroalkyl group having the general formula (CH2)x-CyF2y+1 where x = 1-5 and y = 4-10 and wherein B is an unfunctionalized aryl, alkyl or arylalkyl group Pn a preferred embodiment, x = 2 and y = 6 and B is derived from unfunctionalized ammo acids The ammo acids may be from either the D- or L- series, and are preferably enantiomeπcally pure or in very high enantiomeric excess in either configuration.
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-
Page/Page column 6
(2008/06/13)
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- Synthesis of chiral tropopodands having l-amino acid moieties and ability of their metal complexes as an asymmetric catalyst
-
Optical active tropopodans (10 and 11) having neutral l-amino acids and l-histidine moieties were synthesized. Within their metal complexes, Pd complexes of histidine-tropopodands (11b and 11c) bearing bulky amide moieties showed good ability as an asymmetric catalyst in conjugate addition.
- Sato, Ohki,Koshiba, Yusuke,Sagara, Satoshi,Okada, Katsuyoshi
-
p. 529 - 533
(2007/10/03)
-