- Propargyloxycarbonyl and propargyl groups for novel protection of amino, hydroxy, and carboxy functions
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The propargyloxycarbonyl group readily introduced to both amino and hydroxy groups by using propargyl chloroformate is stable to neat TFA but is readily cleaved at ambient temperature by treatment with Co2(CO)8 and TFA in CH2Cl2 via formation of an alkyne-Co complex. The propargyl ester similarly serves as a good protecting group for carboxy functions.
- Kukase,Fukase,Kusumoto
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- Synthesis and Reactivity of 5-Substituted Furfuryl Carbamates via Oxanorbornadienes
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Furfuryl carbamates are labile and require care to be accessed by activating furfuryl alcohols. An alternative oxanorbornadiene (OND)-based strategy is presented for the preparation of 5-R-substituted furfuryl carbamates via the reactions of amines with intermediate OND carbonates. The resulting OND carbamates, which are stable for several months, undergo thiol mediated retro-Diels-Alder reaction to deliver the desired furfuryl carbamates in a single flask. Conditions for the selective hydrolysis of furfuryl carbamates in the presence of tert-butyloxycarbonyl (Boc) groups were identified, and it was shown that furfuryl carbamates can be used as a prodrug handle.
- Tekkam, Srinivas,Finn
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- Formation of lanthanide complexes with bipyridine-functionalized amide compounds and their unusually high amide reactivity
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The amide of 6-benzoylamino-6'-L-phenylalanyl-amino-2,2'-bipyridine (1a) was efficiently cleaved at 30°C to generate L-phenylalanine ester in methanol almost quantitatively. The reaction followed the Michaelis-Menten type via the 1:1 1a-Ln3+ complex. The half-life time of the scissile amide bond of the complex was as short as 2 min for the complex. The reactions depended on the structure of the substrates, which require 2,2'-bipyridine with two acylamino side chains at the 6,6'-positions and an amino group at the α-position of the scissile carbonyl. The less reactive 6-6'bis(benzoylamino)-2,2'-bipyridine with lanthanide cations formed 1:1 complexes. The formation constants were on the order of 103-105 cu dm/mole in methanol at 30°C. Coordination of the bipyridine nitrogens and the carbonyl oxygens was demonstrated in chloroform although coordination of the carbonyl oxygens was not seen in methanol.
- Araki,Kawaguchi,Kajikawa,Kaneko,Koshimizu
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- A green route for the synthesis of a bitter-taste dipeptide combining biocatalysis, heterogeneous metal catalysis and magnetic nanoparticles
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There is increasing demand for green technologies to produce high-solubility and low-toxicity compounds with potential application in the food industry. This study aimed to establish a clean, synthetic route for preparing the bitter-taste dipeptide Ala-Phe, a potential substitute for caffeine as a food additive. Synthesis of Z-Ala-Phe-OMe starting from Z-Ala-OH and HCl·Phe-OMe was catalysed by thermolysin at 50 °C in buffer (step 1). Z-Ala-Phe-OMe ester hydrolysis to give Z-Ala-Phe-OH at 37 °C in 30% acetonitrile/buffer was catalysed by α-bovine chymotrypsin (αCT), protease with esterase activity (step 2). Hydrogenation of Z-Ala-Phe to give the desired Ala-Phe was catalysed by C/Pd in methanol (step 3). Steps 2 and 3 were optimized by using the magnetically recoverable recycling enzyme Fe3O4@silica-αCT and the magnetically recoverable metal nanocatalyst Fe3O4@silica-Pd, respectively. This inspiring combination of technologies and the original results demonstrate the suitability of using enzymes, metal catalyst and magnetic nanoparticles for easy, economical, stereoselective, clean production of an important target compound. Besides, they add to the development of peptide chemistry and catalysis.
- Ungaro, Vitor A.,Liria, Cleber W.,Romagna, Carolina D.,Costa, Natália J. S.,Philippot, Karine,Rossi, Liane M.,Machini, M. Teresa
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- Chiral N-hydroxybenzamides as potential catalysts for aerobic asymmetric oxidations
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Chiral N-hydroxybenzamides (1H-3H) have been synthesized as precursors of chiral short-lived N-oxyl radicals 1?-3?. The latter species have been generated by oxidation of 1H-3H with Pb(OAc)4 or hydrogen abstraction from 1H-3H by the tert-butoxyl radical and characterized by UV-vis spectrophotometry and EPR spectroscopy. Through a kinetic study of the hydrogen atom transfer processes promoted by 1?-3? from three chiral benzylic substrates (1-phenylethylamine, 1-phenylethanol, and α-vinylbenzyl alcohol), a moderate chiral discrimination has been found, with selectivity factors 0.5 ≥ kH(S)/kH(R) ≥ 2.
- Capraro, Maria Grazia,Franchi, Paola,Lanzalunga, Osvaldo,Lapi, Andrea,Lucarini, Marco
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- 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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supporting information
p. 390 - 398
(2021/01/13)
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- Stereoretentive N-Arylation of Amino Acid Esters with Cyclohexanones Utilizing a Continuous-Flow System
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The N-arylation of chiral amino acid esters with minimal racemization is a challenging transformation because of the sensitivity of the α-stereocenter. A versatile synthetic method was developed to prepare N-arylated amino acid esters using cyclohexanones as aryl sources under continuous-flow conditions. The designed flow system, which consists of a coil reactor and a packed-bed reactor containing a Pd(OH)2/C catalyst, efficiently afforded the desired N-arylated amino acids without significant racemization, accompanied by only small amounts of easily removable co-products (i. e., H2O and alkanes). The efficiency and robustness of this method allowed for the continuous synthesis of the desired product in very high yield and enantiopurity with high space-time yield (74.1 g L?1 h?1) and turnover frequency (5.9 h?1) for at least 3 days.
- Ichitsuka, Tomohiro,Komatsuzaki, Shingo,Masuda, Koichiro,Koumura, Nagatoshi,Sato, Kazuhiko,Kobayashi, Shū
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supporting information
p. 10844 - 10848
(2021/05/31)
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- Continuous flow heterogeneous catalytic reductive aminations under aqueous micellar conditions enabled by an oscillatory plug flow reactor
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Despite the fact that continuous flow processing exhibits well-established technical advances, aqueous micellar chemistry, a field that has proven extremely useful in shifting organic synthesis to sustainable water-based media, has mostly been explored under conventional batch-based conditions. This is particularly because of the fact that the reliable handling of slurries and suspensions in flow has been considered as a significant technical challenge. Herein, we demonstrate that the strategic application of an oscillatory plug flow reactor enables heterogeneous catalytic reductive aminations in aqueous micellar media enhancing mass transport and facilitating process simplicity, stability and scalability. The micellar flow process enabled a broad range of substrates, including amino acid derivatives, to be successfully transformed under reasonably mild conditions utilizing only very low amounts of Pd/C as a readily available heterogeneous catalyst. The preparative capabilities of the process along with the recyclability of the heterogenous catalyst and the aqueous reaction media were also demonstrated. This journal is
- ?tv?s, Sándor B.,Buchholcz, Balázs,Darvas, Ferenc,Kappe, C. Oliver,Novák, Zoltán,Sipos, Gellért,Wernik, Michaela
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supporting information
p. 5625 - 5632
(2021/08/16)
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- Transition Metal-Free N-Arylation of Amino Acid Esters with Diaryliodonium Salts
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A transition metal-free approach for the N-arylation of amino acid derivatives has been developed. Key to this method is the use of unsymmetric diaryliodonium salts with anisyl ligands, which proved important to obtain high chemoselectivity and yields. The scope includes the transfer of both electron deficient, electron rich and sterically hindered aryl groups with a variety of different functional groups. Furthermore, a cyclic diaryliodonium salt was successfully employed in the arylation. The N-arylated products were obtained with retained enantiomeric excess.
- Kervefors, Gabriella,Kersting, Leonard,Olofsson, Berit
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supporting information
p. 5790 - 5795
(2021/03/08)
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- A General Stereocontrolled Synthesis of Opines through Asymmetric Pd-Catalyzed N-Allylation of Amino Acid Esters
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A stereo-divergent synthesis of natural and unnatural opines in stereochemically pure form is based on the direct palladium-catalyzed N-allylation of α-amino acid esters (up to 97 % ee or 99 : 1 d.r.) using methyl (E)-2-penten-4-yl carbonate in the presence of only 1 mol% of a catalyst, prepared in-situ from the C2-symmetric diphosphine iPr-MediPhos and [Pd(allyl)Cl]2. Selected target compounds (incl. a derivative of the drug enalapril) were efficiently obtained from the N-allylated intermediates by oxidative cleavage (ozonolysis) of the allylic C=C bond under temporary N-Boc-protection.
- Albat, Dominik,Neud?rfl, J?rg-Martin,Schmalz, Hans-Günther
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supporting information
p. 2099 - 2102
(2021/07/22)
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- Guanidine-containing compound as well as preparation method and application thereof
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The invention discloses a cyanoguanidine-containing compound as well as a preparation method and application thereof. The invention also discloses a composition containing the cyanoguanidine-structured compound (I) or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier. The invention also discloses application thereof in preparation of analgesic drugs. The compounds of the invention are useful in the treatment of various pain.
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Paragraph 0038-0041
(2021/11/26)
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- Identification of inhibitors of UDP-galactopyranose mutaseviacombinatorialin situscreening
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Anin situscreening assay for UDP-galactopyranose mutase (UGM, an essential enzyme ofM. tuberculosiscell wall biosynthesis) has been developed to discover novel UGM inhibitors. The approach is based on the amide-forming reaction of an amino acid core with various cinnamic acids, followed by a direct fluorescence polarization assay to identify the best UGM binders without isolation and purification of the screened ligands. This assay allows us to perform one-pot high-throughput synthesis and screening of enzyme inhibitors in a 384-well plate format. UGM ligands were successfully identified by this technology and their inhibition levels were established from pure synthetic compoundsin vitroand in a whole cell antibacterial assay. This study provides a blueprint for designing enamide structures as new UGM inhibitors and anti-mycobacterial agents.
- Fu, Jian,Fu, Huixiao,Xia, Yufen,N'Go, Inès,Cao, Jun,Pan, Weidong,Vincent, Stéphane P.
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p. 1818 - 1826
(2021/03/14)
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- C3 The symmetry contains a chiral ligand H3L of an amide bond. Preparation method and application
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The invention discloses C. 3 Chiral ligand H with symmetric amide bond3 L Relates to the technical field of material chemistry and chiral chemistry. The invention further provides the chiral ligand H. 3 L Preparation method and application thereof. The present invention has the advantage that the chiral ligand H of the present invention is a chiral ligand. 3 The L has a higher C. 3 The symmetric and flexible amide group enables coordination of the lanthanide metal ions with high coordination number and high oxygen affinity to be assembled into a novel structure-structure lanthanide metal chiral porous coordination cage. Moreover, the abundant chiral amide groups and amino acid residues on the ligand framework can be directly introduced into the synthesized lanthanide metal chiral porous coordination cage, thereby being beneficial to generating multiple chiral recognition sites and unique chiral microenvironments which mimic the biological enzyme binding pocket and further realize the purpose of high enantioselectivity separation of a series of chiral small molecule compounds.
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Paragraph 0071-0073; 0075
(2021/09/08)
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- Homochiral Dodecanuclear Lanthanide "cage in Cage" for Enantioselective Separation
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It is extremely difficult to anticipate the structure and the stereochemistry of a complex, particularly when the ligand is flexible and the metal node adopts diverse coordination numbers. When trivalent lanthanides (LnIII) and enantiopure amino acid ligands are utilized as building blocks, self-assembly sometimes yields rare chiral polynuclear structures. In this study, an enantiopure carboxyl-functionalized amino acid-based ligand with C3 symmetry reacts with lanthanum cations to give a homochiral porous coordination cage, (Δ/λ)12-PCC-57. The dodecanuclear lanthanide cage has an unprecedented octahedral "cage-in-cage"framework. During the self-assembly, the chirality is transferred from the enantiopure ligand and fixed by the binuclear lanthanide cluster to give 12 metal centers that have either Δor λ homochiral stereochemistry. The cage exhibits excellent enantioselective separation of racemic alcohols, 2,3-dihydroquinazolinones, and multiple commercially available drugs. This finding exhibits a rare example of a multinuclear lanthanide complex with a dual-walled topology and homochirality. The highly ordered self-assembly and self-sorting of flexible amino acids and lanthanides shed light on the chiral transformation between different complicated artificial systems that mimic natural enzymes.
- Zhu, Chengfeng,Tang, Haitong,Yang, Keke,Fang, Yu,Wang, Kun-Yu,Xiao, Zhifeng,Wu, Xiang,Li, Yougui,Powell, Joshua A.,Zhou, Hong-Cai
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supporting information
p. 12560 - 12566
(2021/08/23)
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- Enantioselective Aza-Diels Alder reaction catalyzed by clay supported Schiff base complex?
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Clay supported catalysts based on 2- hydroxy naphthaldehyde and amino acids, their copper and titanium complexes have been described. The catalysts were found to be active toward the synthesis of pyrano-, furanoquinolines through Aza-Diels Alder reaction. The catalysts gave good yield and high enantioselectivity. The catalysts were environmentally friendly, economical, synthetically robust and reusable.
- Kannan,Sreekumar
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supporting information
p. 153 - 160
(2020/10/20)
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- Preparation method of oxazolidinone compound
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The preparation method comprises the following steps 1): dissolving aromatic amino acid in methanol, dissolving the aromatic amino acid in methanol, heating up to 50 - 60 °C heat preservation 1 - 2h, 2) reducing: adding a catalytic amount of lithium salt in ethanol water as a solvent. 3) Ring-closing: toluene is used as a solvent, a reduction product and diethyl carbonate are added to 100 °C, a sodium methoxide solution is added dropwise, and the product is obtained after completion of the dropwise addition and after-treatment and purification after completion of the normal pressure distillation to the temperature of 100 °C heat preservation. The lithium salt is introduced to participate in the reaction, sodium borohydride is selected as a solvent, sodium borohydride is completely dissolved, and the lithium salt can be free from the compound to improve the reaction activity, so that the use amount of sodium borohydride is reduced to 2 equivalent, and the production cost is remarkably reduced.
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Paragraph 0044-0046
(2021/11/10)
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- Continuous Synthesis of Aryl Amines from Phenols Utilizing Integrated Packed-Bed Flow Systems
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Aryl amines are important pharmaceutical intermediates among other numerous applications. Herein, an environmentally benign route and novel approach to aryl amine synthesis using dehydrative amination of phenols with amines and styrene under continuous-flow conditions was developed. Inexpensive and readily available phenols were efficiently converted into the corresponding aryl amines, with small amounts of easily removable co-products (i.e., H2O and alkanes), in multistep continuous-flow reactors in the presence of heterogeneous Pd catalysts. The high product selectivity and functional-group tolerance of this method allowed aryl amines with diverse functional groups to be selectively obtained in high yields over a continuous operation time of one week.
- Ichitsuka, Tomohiro,Kobayashi, Shū,Koumura, Nagatoshi,Sato, Kazuhiko,Takahashi, Ikko
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supporting information
p. 15891 - 15896
(2020/07/13)
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- Synthesis and Penicillin-binding Protein Inhibitory Assessment of Dipeptidic 4-Phenyl-β-lactams from α-Amino Acid-derived Imines
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Monocyclic β-lactams revive the research field on antibiotics, which are threatened by the emergence of resistant bacteria. A six-step synthetic route was developed, providing easy access to new 3-amino-1-carboxymethyl-4-phenyl-β-lactams, of which the penicillin-binding protein (PBP) inhibitory potency was demonstrated biochemically.
- Decuyper, Lena,Juki?, Marko,Sosi?, Izidor,Amoroso, Ana Maria,Verlaine, Olivier,Joris, Bernard,Gobec, Stanislav,D'hooghe, Matthias
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supporting information
p. 51 - 55
(2019/11/28)
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- Mechanoresponsive, proteolytically stable and biocompatible supergelators from ultra short enantiomeric peptides with sustained drug release propensity
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Stimuli-responsive low molecular weight hydrogelators attract immense interest from diverse segments of biomedicine and biotechnology. Distinctly, herein we report newly synthesized enantiomeric ultrashort peptides of general formula Me-(CH2)8-CO-NH-CH(X)-COOH, where X = CH2Ph in hydrogelators I (l-Phe) and II (d-Phe) respectively, which display excellent self-assembling propensity in physiological buffer at room temperature. Interestingly these biomolecules were endowed with mechanoresponsiveness, injectability and high mechanical integrity as confirmed by rheological measurements. Importantly they revealed resistance towards proteolytic degradation. Indeed dose dependent cell viability studies using MTT assay in four different cell lines, namely PANC-1, S1, HCT-116 and MDAMB-231, further confirmed the biocompatibility of the hydrogelators in vitro. The structural aspect of β-sheets of the hydrogelators was concluded on the basis of temperature dependent NMR, IR, PXRD and computational studies. We developed a user friendly delivery system, hydrogel nanoparticles (HNPs), with our mechanoresponsive and biocompatible hydrogelators, as these particles exhibited promising influence due to their enhanced surface area. Also the HNPs revealed excellent drug release kinetics for the model drugs 5FU/doxorubicin under physiological conditions in a sustained manner depending on the physicochemical parameters of the drugs. Taking these results together we envision that our designed hydrogelators and the delivery vehicle generated therefrom might represent a promising tool for administration of significant drug concentrations at lesion sites for a prolonged period, thus providing a better strategy for quick pain relief, rapid recovery and reduced systemic side effects.
- Basu, Anindya,Christman, Ryann M.,Duttkonar, Anita,Harjit, Jeena,Mehra, Radha Rani,Mishra, Anil K.,Tiwari, Amit K.
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p. 6346 - 6354
(2020/05/13)
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- Synthesis and evaluation of antitumor activities of 4-selenopyrimidine derivatives
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Pyrimidine antimetabolic agents are the essential drugs in treatment of various tumors. Novel synthesis and biological evaluation of the pyrimidine derivatives incorporating selenium element and amino acid carrier as potential antitumor agents have not been tried and studied. Based on the biological significance of pyrimidine structure, these two additional elemental fragments maybe enhance the antitumor effect and reduce toxic side effects of pyrimidine agents. The aim of this paper is to synthesis a series of 4-selenopyrimidine derivatives in order to find more potent lead compounds against cancer. In this study, 12 new 4-selenopyrimidine derivatives that are unstable in acidic solutions but very stable in alkaline and neutral solutions avoiding light were synthesized, and the antitumor activities on HepG2 cell lines of these compounds were evaluated by MTT assay. The results have shown that these compounds could reduce the proliferation of HepG2 cells in a dose-dependent fashion, and the inhibitory activity of compounds a6 was greater than that of positive control 5-fluorouracil (5-FU), the IC50 for a6 was 3.63 μM. In the comprehensive analysis of the structure–activity relationship, we could draw the antitumor effect of selenouracil derivatives is stronger than those of selenothymine derivatives. These results suggest that the substituent groups of selenium element and amino acid on the pyrimidine derivatives are vital for their antitumor activities on HepG2 cells.
- Shi, Mingxing,Wang, Libo,Zhang, Long,Wang, Kexin,Zhang, Hualin,Wang, Yajing,Li, Chang,Han, Weina
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- Design, synthesis and evaluation of the antibacterial activity of new Linezolid dipeptide-type analogues
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Worldwide studies towards development of new drugs with a lower rate in emergence of bacterial resistance have been conducted. The molecular docking analysis gives a possibility to predict the activity of new compounds before to perform their synthesis. In this work, the molecular docking analysis of 64 Linezolid dipeptide-type analogues was performed to predict their activity. The most negative scores correspond to six Fmoc-protected analogues (9as, 9bs, 9bu, 10as, 10ax and 10ay) where Fmoc group interacts in PTC for Linezolid. Twenty-six different Fmoc-protected Linezolid dipeptide-type analogues 9(as-bz) and 10(as-bz) were synthesized and tested in antimicrobial experiments. Compounds 9as, 9ay, 9ax, 10as, 10ay and 9bu show significant activity against group A Streptococcus clinical isolated. Analogue 10ay also display high activity against ATCC 25923 Staphylococcus aureus strain and MRSA-3, MRSA-4 and MRSA-5 clinical isolates, with MIC values lower than Linezolid. The highest activity against multidrug-resistant clinical isolates of Mycobacterium tuberculosis was exhibited by 9bu. Finally, a cytotoxicity assay with ARPE-19 human cells revealed a non-cytotoxic effect of 9bu and 10ay at 50 and 25 μM, respectively.
- García-Olaiz,Alcántar-Zavala, Eleazar,Ochoa-Terán, Adrián,Cabrera, Alberto,Mu?iz-Salazar, Raquel,Montes-ávila, Julio,Salazar-Medina, Alex J.,Alday, Efrain,Velazquez, Carlos,Medina-Franco, José L.,Laniado-Laborín, Rafael
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supporting information
(2019/12/23)
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- Synthesis and photophysics of benzazole based triazoles with amino acid-derived pendant units. Multiparametric optical sensors for BSA and CT-DNA in solution
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Herein we report the synthesis of a series of amino acid-derived triazoles by an organocatalytic cycloaddition reaction between azides and carbonyl compounds, catalyzed by a simple amine. These compounds present absorption maxima located in the UV-B ascribed to fully spin and symmetry allowed electronic transitions and a main fluorescence emission in the UV-A (~380 nm) with a relatively large Stokes shift (5700 cm?1). No significant solvatochromism was observed in both ground and excited states. Unexpectedly, the benzoxazole derivatives presented much higher fluorescence quantum yield values (40–80%) of compared to the sulfur analogues (3–6%). In addition, the DNA binding assays indicated that these compounds presented strong interaction with CT-DNA, which could be attributed to π-stacking and intermolecular hydrogen-bonding. The interaction of the benzazoles with bovine serum albumin (BSA) was also investigated, where a suppression mechanism was observed. In each case, docking was performed to better understand the observed interactions.
- Debia, Natalí P.,Rodríguez, Juan J.P.,da Silveira, Carolina H.,Chaves, Otavio A.,Iglesias, Bernardo A.,Rodembusch, Fabiano S.,Lüdtke, Diogo S.
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- Self-assembled dipeptide nanospheres as single component based delivery vehicle for ampicillin and doxorubicin
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Effective delivery of therapeutic agents encounters many challenges such as uncontrolled drug release, low bioavailability of drugs, degradation of drugs in the intestinal transit and non-biocompatibility of the delivery vehicle. Thus, in the quest for advance drug delivery system, self-assembled dipeptide (Fmoc-L-Trp-L-Phe-OCH3) nanospheres (SPNS) were generated in aqueous medium with size ranging between 100 and 400 nm. The SPNS were examined for the presence of hydrophobic and hydrophilic domains which was followed by drug loading analysis (ampicillin and doxorubicin) into SPNS using HPLC. Further, SPNS demonstrated pH triggered morphological alterations leading to controlled release of loaded therapeutics. Additionally, SPNS exhibited low cytotoxicity and exceptional stability against enzymatic degradation. The system was further analyzed for in vitro cellular internalization of therapeutics. Thus, outcome of this analysis indicated that SPNS acts as single component, multifunctional drug delivery vehicle by addressing critical issues such as effective drug loading, pH responsive controlled release, biocompatibility, and stability against enzymatic degradation.
- Katare, Om P.,Manhas, Priya,Pandey, Satish K.,Sharma, Rohit,Sharma, Rohit K.,Singh, Prabhjot,Wangoo, Nishima
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- Urethanes synthesis from oxamic acids under electrochemical conditions
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Urethane synthesis via oxidative decarboxylation of oxamic acids under mild electrochemical conditions is reported. This simple phosgene-free route to urethanes involves an in situ generation of isocyanates by anodic oxidation of oxamic acids in an alcoholic medium. The reaction is applicable to a wide range of oxamic acids, including chiral ones, and alcohols furnishing the desired urethanes in a one-pot process without the use of a chemical oxidant.
- Ogbu, Ikechukwu Martin,Lusseau, Jonathan,Kurtay, Gülbin,Robert, Frédéric,Landais, Yannick
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supporting information
p. 12226 - 12229
(2020/10/26)
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- Nickel-Catalyzed Asymmetric Hydrogenation of 2-Amidoacrylates
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Earth-abundant nickel, coordinated with a suitable chiral bisphosphine ligand, was found to be an efficient catalyst for the asymmetric hydrogenation of 2-amidoacrylates, affording the chiral α-amino acid esters in quantitative yields and excellent enantioselectivity (up to 96 % ee). The active catalyst component was studied by NMR and HRMS, which helped us to realize high catalytic efficiency on a gram scale with a low catalyst loading (S/C=2000). The hydrogenated products could be simply converted into chiral α-amino acids, β-amino alcohols, and their bioactive derivatives. Furthermore, the catalytic mechanism was investigated using deuterium-labeling experiments and computational calculations.
- Chen, Jianzhong,Gridnev, Ilya D.,Hu, Yawen,Li, Bowen,Zhang, Wanbin,Zhang, Zhenfeng
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supporting information
p. 5371 - 5375
(2020/02/15)
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- Glycerol conversion to high-value chemicals: The implication of unnatural α-amino acid syntheses using natural resources
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Glycerol derivatives are an important class of compounds, which have great applications as basic structural building blocks in organic synthesis. O-Benzylglycerol was oxidised to produce a high-value compound in high yield using a NaOtBu-O2 system. Furthermore, the synthetic utility of the resulting product was demonstrated by its transformation into unnatural α-amino acids, thus showing the valorisation of glycerol biomass.
- Park, Yun Ji,Yang, Jung Woon
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p. 2615 - 2620
(2019/06/03)
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- Postsynthetic Modification of Phenylalanine Containing Peptides by C-H Functionalization
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New methods for peptide modification are in high demand in drug discovery, chemical biology, and materials chemistry; methods that modify natural peptides are particularly attractive. A Pd-catalyzed, C-H functionalization protocol for the olefination of phenylalanine residues in peptides is reported, which is compatible with common amino acid protecting groups, and the scope of the styrene reaction partner is broad. Bidentate coordination of the peptide to the catalyst appears crucial for the success of the reaction.
- Terrey, Myles J.,Perry, Carole C.,Cross, Warren B.
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supporting information
p. 104 - 108
(2019/01/11)
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- In search of bioinspired hydrogels from amphiphilic peptides: A template for nanoparticle stabilization for the sustained release of anticancer drugs
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The development of potent stimuli-responsive hydrogels has rapidly expanded in the last decades due to their diversified applications in the field of biomedicines. In accordance with this drift, herein, we aimed at modulating a series of amphiphilic peptide analogues with the general formula Me-(CH2)14-CO-NH-CH(X)-COOH, where X = CH2Ph in hydrogelators I (l-Phe) and II (d-Phe) and X = CH2Ph(OH) in hydrogelator III (l-Tyr), which displayed an excellent propensity to immobilize water at room temperature with a minimum gelation concentration of 0.04%/0.05%/0.02% w/v for hydrogelators I-III, respectively, regardless of their configuration at the C-terminal centre. To validate this threshold concentration difference, we performed computational analysis that demonstrated the ability of the side-chains of hydrogelators I and III to remain highly planar with the methylene units of the amphiphile and aromatic rings, promoting favourable correspondence through van der Waals forces and pi-pi stacking. Consequently hydrogelators I and III self-assembled in an ordered organisation superior to hydrogelator II. Furthermore, the spectroscopic and microscopic experiments revealed that the hydrogelators manifested a β-sheet conformation and nanofibrous morphology at the supramolecular level. As observed visually and additionally confirmed by differential scanning calorimetry (DSC) and rheological measurements, the hydrogels exhibited thermo-reversibility, injectability and high mechanical strength. Importantly, these biomaterials were also found to be resistant towards proteolytic degradation and non-cytotoxic in the cell line HEK 293 using a dose-dependant cell viability assay. To date, the development of a structured approach for the release of drugs in a predictable manner from an optimised formulation, using peptide-based hydrogel nanoparticles as a delivery system remains in its infancy. Hence, we developed hydrogel nanoparticles (HNPs) with our fabricated amphiphilic peptides that exploited the weak noncovalent interactions for their fabrication, unlike other cross-linked polymers that require strong covalent or ionic bonds for their formation. Interestingly, the as-synthesized nanoparticles showed an unprecedented ability to release the anticancer drugs 5-fluoro uracil/doxorubicin at physiological conditions depending on the physico-chemical parameters of the drugs. We believe that the reported injectable, biocompatible, amphiphilic peptide-based hydrogels hold future promise as a potential tool to transport drugs to a targeted site at a greater concentration, thus relieving the patient from surgical injury and simultaneously aiding in a faster recovery.
- Mehra, Radha Rani,Tiwari, Priyanka,Basu, Anindya,Duttkonar, Anita
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p. 11666 - 11678
(2019/07/31)
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- Preparation and biological evaluation of soluble tetrapeptide epoxyketone proteasome inhibitors
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A series of novel tetrapeptidyl epoxyketone inhibitors of 20S proteasome was designed and synthesized. To fully understand the SAR, various groups at R1, R2, R3, R4 and R5 positions, including aromatic and aliphatic substituents were designed, synthesized and biologically assayed. Based on the enzymatic results, seven compounds were selected to evaluate their cellular activities and soluble compound 36 showed strong potency against human multiple myeloma (MM) cell lines. Microsomal stability results indicated that compound 36 was more stable in mice, rat and human microsomes than marketed carfilzomib. The in vivo activities of this compound were evaluated with the xenograft mice models of MM cell lines ARH77 and RPMI-8226 with luciferase expression and the T/C value of the two models were 49.5% and 37.6%, respectively. To evaluate the potential cardiovascular toxicity, inhibition of hERG ion channel in HEK293 cells by compound 36 and carfilzomib was carried out. The results indicated that 36 had no binding affinity for the hERG ion channel while carfilzomib could bind it with IC50 of 92.1 μM.
- Lei, Meng,Zhang, Haoyang,Miao, Hang,Du, Xiao,Zhou, Hui,Wang, Jia,Wang, Xueyuan,Feng, Huayun,Shi, Jingmiao,Liu, Zhaogang,Shen, Jian,Zhu, Yongqiang
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p. 4151 - 4162
(2019/08/07)
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- Palladium-Catalyzed C(sp2)-H Olefination of Free Primary and Secondary 2-Phenylethylamines: Access to Tetrahydroisoquinolines
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A rapid construction of THIQs by a Pd(II)-catalyzed C(sp2)-H olefination of free primary and secondary 2-phenylethylamines with high step- and atom-economy was reported. Notably, no substituent was required at the α-position to the amino group of the 2-phenylethylamines. The substrate scope was broad, and the reaction could also be applied to generate THIQs from the biologically active molecules such as the drug molecule baclofen and phenylalanine ester.
- Fan, Shuai,Ding, Yongzheng,Chen, Xiaoxi,Gao, Yuzhen,Fu, Lei,Li, Shangda,Li, Gang
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p. 13003 - 13012
(2019/10/11)
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- In situ formation of AuNPs using fatty N-acylamino hydrazide organogelators as templates
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This work reports, for the first time, the synthesis of new fatty N-acylamino hydrazides and demonstrates the activity of these compounds as low-molecular-weight organic gelators and templates for preparation of gold nanoparticles (AuNPs). Initially, we evaluated the gelation properties of fatty N-acylamino hydrazides in various nonpolar and polar solvents (n-hexane, toluene, benzene, cyclohexane, and ethanol). Fatty N-acylamino hydrazide derived of the glycine and stearic acid (C18:0) did not form gels in any of the tested solvents. All other hydrazides did form gels in at least two of the organic solvents tested. The morphology of each gel was observed via scanning electron microscopy. The organogels derived from alanine, valine, and phenylalanine had translucid properties, while the serine organogels were opaque. Afterwards, the synthesis of AuNPs in the presence of the organogelator using microwave irradiation was realized. Organogelator agents reduced HAuCl4 showing plasmon band peaks between 530 and 543 nm. In addition, the method does not require a reducing agent, which is typically a potential source of contamination and toxicity. Therefore, this work confirms the importance of the hydrazide group of the new fatty N-acylamino hydrazides in gel formation and as organogelator agents for preparation of AuNPs.
- Ongaratto, Renata,Conte, Naiane,Montes D'Oca, Caroline R.,Brinkerhoff, Rafael C.,Ruas, Caroline Pires,Gelesky, Marcos Alexandre,Montes D'Oca, Marcelo G.
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p. 295 - 303
(2019/01/04)
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- Catalytic Mechanism Study on the 1,2- and 1,4-Transfer Hydrogenation of Ketimines and β-Enamino Esters Catalyzed by Axially Chiral Biscarboline-Based Alcohols
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Axial N-O alcohols, which have two large carboline moieties connected to the axis were synthesized and used in catalytic enantioselective 1,2- and 1,4-transfer hydrogenations of total 26 ketimines and β-enamino esters. Excellent levels of enantioselectivity ranging from 91% to 99% were achieved by using catalyst (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide. Interestingly, a mixture of (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide and (aR)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide was also able to provide high enantioselectivities up to 95% that is the same as that using pure (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide. A plausible catalytic mechanism was suggested and total four kinds of transition states (TS) including almost 60 TS structures were investigated using density functional theory (DFT) with different basis sets such as 6-311G(2d,p). The predicted activation energy data are consistent with the experimental results. (Figure presented.).
- Dong, Mengxian,Wang, Jie,Wu, Shijie,Zhao, Yang,Ma, Yangyang,Xing, Yongfei,Cao, Fei,Li, Longfei,Li, Zhenqiu,Zhu, Huajie
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supporting information
p. 4602 - 4610
(2019/08/30)
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- Pure organic amino acid derivative for room-temperature phosphorescence emission, preparation method thereof and organic luminescent material
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The invention provides a pure organic amino acid derivative for room-temperature phosphorescence emission and a preparation method thereof. The pure organic amino acid derivative for room-temperaturephosphorescence emission has a structure as shown in a formula (I). The pure organic amino acid derivatives for room-temperature phosphorescence emission are obtained by combining various pure organicphosphorescence monomers with an amino acid derivative, the reaction raw materials are easy to obtain, the reaction process is simple, the product is non-toxic and harmless, and the defects of complex preparation of crystalline organic room-temperature phosphorescence materials and the like are overcome.
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- Practical Cleavage of Acetals by Using an Odorless Thiol Immobilized on Silica
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A practical, efficient and general method was developed for the deprotection of a variety of aromatic and aliphatic acetals to their corresponding catechol or diol derivatives using thiol immobilized on silica gel. This is an application for the well-known commercial solid-supported thiol (SiliaMetS Thiol). The procedure is mild and amenable to scale-up. It does not require inert atmosphere and clean conversions were observed. This method is applicable to substituted 1,3-benzodioxole and aliphatic acetals with different functionalities. It offers the advantage of a general route with high yield, which can be undertaken at ambient temperature.
- de Léséleuc, Mylène,Kukor, Andrew,Abbott, Shaun D.,Zacharie, Boulos
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p. 7389 - 7393
(2019/12/03)
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- Cleavable Amide Bond: Mechanistic Insight into Cleavable 4-Aminopyrazolyloxy Acetamide at Low pH
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The cleavage of amide bonds under mild acidic conditions is a rare chemical event. N-Acetamide bond of peptides is extremely stable even under the strongest organic acid trifluoromethanesulfonic acid. This report mechanistically describes a new cleavable amide bond in 4-aminopyrazolyloxy acetamide peptide analogues under mild acidic conditions such as trifluoroacetic acid (10-20%) or HCl (0.1-4.0 N) at room temperature, and the formation of unusual lactam from 4-aminopyrazolyloxy acetic acid after evaporation of solvent. This is a rare chemical event in peptide bond, which could be explored as acid-sensitive protecting group of free amines.
- Bollu, Amarnath,Sharma, Nagendra K.
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supporting information
p. 5596 - 5602
(2019/05/10)
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- Cleavable Amide Bond: Mechanistic Insight into Cleavable 4-Aminopyrazolyloxy Acetamide at Low pH
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The cleavage of amide bonds under mild acidic conditions is a rare chemical event. N-Acetamide bond of peptides is extremely stable even under the strongest organic acid trifluoromethanesulfonic acid. This report mechanistically describes a new cleavable amide bond in 4-aminopyrazolyloxy acetamide peptide analogues under mild acidic conditions such as trifluoroacetic acid (10-20%) or HCl (0.1-4.0 N) at room temperature, and the formation of unusual lactam from 4-aminopyrazolyloxy acetic acid after evaporation of solvent. This is a rare chemical event in peptide bond, which could be explored as acid-sensitive protecting group of free amines.
- Bollu, Amarnath,Sharma, Nagendra K.
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supporting information
(2019/05/08)
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- Unlocking the potential of phenacyl protecting groups: CO2-based formation and photocatalytic release of caged amines
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Orthogonal protection and deprotection of amines remain important tools in synthetic design as well as in chemical biology and material research applications. A robust, highly efficient, and sustainable method for the formation of phenacyl-based carbamate esters was developed using CO2 for the in situ preparation of the intermediate carbamates. Our mild and broadly applicable protocol allows for the formation of phenacyl urethanes of anilines, primary amines, including amino acids, and secondary amines in high to excellent yields. Moreover, we demonstrate the utility by a mild and convenient photocatalytic deprotection protocol using visible light. A key feature of the [Ru(bpy)3](PF6)2-catalyzed method is the use of ascorbic acid as reductive quencher in a neutral, buffered, two-phase acetonitrile/water mixture, granting fast and highly selective deprotection for all presented examples.
- Speckmeier, Elisabeth,Klimkait, Michael,Zeitler, Kirsten
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p. 3738 - 3745
(2018/04/14)
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- Synthesis and anticancer activity of the proposed structure of caldoramide, an N-peptidyltetramate from the cyanobacterium Caldora penicillata
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The structure proposed in the literature for caldoramide, a formal pentapeptide metabolite of the marine cyanobacterium Caldora penicillata, was synthesised in 12 steps and 16% yield (longest linear sequence from isoleucine) following the strategy of a stepwise consecutive extension of an N-oligopeptidyl chain on a tetramate anchor. The synthetic product differed from the natural isolate in optical rotation, some NMR data, and cytotoxicities. Its antiproliferative effect on three human cancer cell lines was distinctly lower than that of related dolastatin 10 and belamide A.
- Wunder, Anja,Rothemund, Matthias,Schobert, Rainer
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supporting information
p. 5138 - 5142
(2018/04/16)
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- Spin-Center Shift-Enabled Direct Enantioselective α-Benzylation of Aldehydes with Alcohols
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Nature routinely engages alcohols as leaving groups, as DNA biosynthesis relies on the removal of water from ribonucleoside diphosphates by a radical-mediated "spin-center shift" (SCS) mechanism. Alcohols, however, remain underused as alkylating agents in synthetic chemistry due to their low reactivity in two-electron pathways. We report herein an enantioselective α-benzylation of aldehydes using alcohols as alkylating agents based on the mechanistic principle of spin-center shift. This strategy harnesses the dual activation modes of photoredox and organocatalysis, engaging the alcohol by SCS and capturing the resulting benzylic radical with a catalytically generated enamine. Mechanistic studies provide evidence for SCS as a key elementary step, identify the origins of competing reactions, and enable improvements in chemoselectivity by rational photocatalyst design.
- Nacsa, Eric D.,MacMillan, David W. C.
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supporting information
p. 3322 - 3330
(2018/03/13)
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- Design, synthesis, and molecular docking studies of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives as xanthine oxidase inhibitors
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A series of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives (1a–j) was designed and synthesized as novel xanthine oxidase inhibitors. Among them, the L/D-phenylalanine derivatives (1d and 1i) and the L/D-tryptophan derivatives (1e and 1j) were effective with micromolar level potency. In particular, the L-phenylalanine derivative 1d (IC50?=?3.0?μm) and the D-phenylalanine derivative 1i (IC50?=?2.9?μm) presented the highest potency and were both more potent than the positive control allopurinol (IC50?=?8.1?μm). Preliminary SAR analysis pointed that an aromatic amino acid fragment, for example, phenylalanine or tryptophan, was essential for the inhibition; the D-amino acid derivative presented equal or greater potency compared to its L-enantiomer; and the 9,10-anthraquinone moiety was welcome for the inhibition. Molecular simulations provided rational binding models for compounds 1d and 1i in the xanthine oxidase active pocket. As a result, compounds 1d and 1i could be promising lead compounds for further investigation.
- Zhang, Ting-Jian,Li, Song-Ye,Yuan, Wei-Yan,Zhang, Yi,Meng, Fan-Hao
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p. 893 - 901
(2018/03/21)
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- Total Synthesis of the Marine Macrolide Amphidinolide F
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A new and efficient convergent approach toward the synthesis of amphidinolide F is described through the assembly of three fragments. The two trans-tetrahydrofurans were built by a diastereoselective C-glycosylation with titanium enolate of bulky N-acetyloxazolidinethiones. The side chain was inserted by a Liebeskind-Srogl cross-coupling reaction. A sulfone condensation/desulfonylation sequence, a Stille cross-coupling, and a macrolactonization were applied to connect the fragments.
- Ferrié, Laurent,Fenneteau, Johan,Figadère, Bruno
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supporting information
p. 3192 - 3196
(2018/06/11)
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- Exciton-Coupled Circular Dichroism Characterization of Monotopically Binding Guests in Host?Guest Complexes with a Bis(zinc porphyrin) Tweezer
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A stiff-stilbene-linked bisporphyrin tweezer with inherent helicity was used for exciton-coupled circular dichroism (ECCD) characterization of a series of monotopically binding amine guest molecules. CD signals were observed for a variety of monoamines at relatively low tweezer/amine (host/guest) ratios between 1 : 10 to 1 : 70. For the amines producing the most intense CD signals, a binding stoichiometry of 1 : 2 was found. A likely explanation is the presence of guest-guest interactions in the complexes. This is supported by the correlation observed between CD signal intensity and magnitude of possible noncovalent binding between the guests, which can be divided into three groups showing no, moderate and strong response, respectively. Further support for this rationalization comes from molecular modelling.
- Olsson, Sandra,Sch?fer, Clara,Blom, Magnus,Gogoll, Adolf
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p. 1169 - 1178
(2019/01/04)
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- Elucidating the Reaction Pathway of Decarboxylation-Assisted Olefination Catalyzed by a Mononuclear Non-Heme Iron Enzyme
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Installation of olefins into molecules is a key transformation in organic synthesis. The recently discovered decarboxylation-assisted olefination in the biosynthesis of rhabduscin by a mononuclear non-heme iron enzyme (P.IsnB) represents a novel approach in olefin construction. This method is commonly employed in natural product biosynthesis. Herein, we demonstrate that a ferryl intermediate is used for C-H activation at the benzylic position of the substrate. We further establish that P.IsnB reactivity can be switched from olefination to hydroxylation using electron-withdrawing groups appended on the phenyl moiety of the analogues. These experimental observations imply that a pathway involving an initial C-H activation followed by a benzylic carbocation species or by electron transfer coupled β-scission is likely utilized to complete C=C bond formation.
- Yu, Cheng-Ping,Tang, Yijie,Cha, Lide,Milikisiyants, Sergey,Smirnova, Tatyana I.,Smirnov, Alex I.,Guo, Yisong,Chang, Wei-Chen
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supporting information
p. 15190 - 15193
(2018/11/23)
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- The reactions of α-amino acids and α-amino acid esters with high valent transition metal halides: synthesis of coordination complexes, activation processes and stabilization of α-ammonium acylchloride cations
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Titanium tetrachloride smoothly reacted with a selection of α-amino acids (aaH) in CH2Cl2 affording yellow to orange solid coordination compounds, 1a-d, in 70-78% yields. The salts [NHEt3][TiCl4(aa)], 2a-b, were obtained from TiCl4/aaH/NEt3 (aa = l-phenylalanine, N,N-dimethylphenylalanine), in 60-65% yields. The complex , 3, was isolated from the reaction of l-proline with NbCl5/NHiPr2, performed in CH2Cl2 at room temperature. The X-ray structure of 3 features a bridging (E)-1,2-bis(3,4-dihydro-2H-pyrrol-5-yl)ethene-1,2-diolate ligand, resulting from the unprecedented C-C coupling between two proline units. Unusually stable α-ammonium acyl chlorides were prepared by the reactions of PCl5/MCln (MCln = NbCl5, WCl6) with l-proline, N,N-dimethylphenylalanine, sarcosine and l-methionine. MX5 (M = Nb, Ta; X = F, Cl) reacted with l-leucine methylester and l-proline ethylester to give ionic coordination compounds, [MX4L2][MX6] (M = Nb, L = Me2CHCH2CH(NH2)CO2Me, X = F, 9; Cl, 11a; M = Nb, X = Cl, , 11c; Ta, 11d), in moderate to good yields. [NbCl5(Me2CHCH2CHNH3CO2Me)][NbCl6], 12, was isolated as a co-product of the reaction of NbCl5 with l-leucine isopropylester, and crystallographically characterized. The reaction of NbCl5 with l-serine isopropylester afforded NbCl3(OCH2CHNHCO2iPr), 13, in 66% yield. The activation of the ester O-R bond was observed in the reactions of l-leucine methyl ester with NbF5 and l-proline ethyl ester with MBr5 (M = Nb, Ta), these reactions proceeding with the release of EtF and EtBr, respectively. All the metal products were characterized by analytical and spectroscopic methods, while DFT calculations were carried out in order to provide insight into the structural and mechanistic aspects.
- Biancalana, Lorenzo,Bortoluzzi, Marco,Ferretti, Eleonora,Hayatifar, Mohammad,Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
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p. 10158 - 10174
(2017/02/15)
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- Anti-trypanosomal activity of non-peptidic nitrile-based cysteine protease inhibitors
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The cysteine protease cruzipain is considered to be a validated target for therapeutic intervention in the treatment of Chagas disease. Anti-trypanosomal activity against the CL Brener strain of T. cruzi was observed in the 0.1 μM to 1 μM range for three nitrile-based cysteine protease inhibitors based on two scaffolds known to be associated with cathepsin K inhibition. The two compounds showing the greatest potency against the trypanosome were characterized by EC50values (0.12 μM and 0.25 μM) that were an order of magnitude lower than the corresponding Kivalues measured against cruzain, a recombinant form of cruzipain, in an enzyme inhibition assay. This implies that the anti-trypanosomal activity of these two compounds may not be explained only by the inhibition of the cruzain enzyme, thereby triggering a putative polypharmacological profile towards cysteine proteases.
- Burtoloso, Antonio C. B.,de Albuquerque, Sérgio,Furber, Mark,Gomes, Juliana C.,Gon?alez, Cristiana,Kenny, Peter W.,Leit?o, Andrei,Montanari, Carlos A.,Quilles, José Carlos,Ribeiro, Jean F. R.,Rocha, Josmar R.
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- Enantiomerically pure piperazines via NaBH4/I2reduction of cyclic amides
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Enantiomerically pure (3S,7R,8aS)-3-phenyloctahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-methyl octahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-isopropyloctahydropyrrolo[1,2-a]pyrazine-7-ol and (3S,7R,8aS)-3-isobutyloctahydropyrrolo[1,2-a]pyrazine-7-ol 16d were synthesized via preparation of the corresponding cyclic amides from enantiomerically pure L-proline and hydroxyproline derivatives followed by reduction using sodium borohydride-iodine.
- Harish, Vagala,Periasamy, Mariappan
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p. 175 - 180
(2017/01/11)
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- SYNTHESIS OF ARYL CYCLOHEXANE CARBOXAMIDE DERIVATIVES USEFUL AS SENSATES IN CONSUMER PRODUCTS
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Synthesis methods to produce a series of carboxamides built off of an (S)-2-amino acid backbone or an (R)-2-amino acid backbone, depending upon the desired diastereomer of the end product.
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Paragraph 0060; 0139; 0140
(2017/03/21)
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- Preparation of dual responsive low-molecular-weight hydrogel for long-lasting drug delivery
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A novel low-molecular-weight hydrogel (LMWG) was fabricated by oligopeptide and phenylboronic acid to obtain a smart molecular hydrogel with dual glucose and pH response for long-term drug delivery in this study. Dual glucose and pH responsiveness of the blank molecular hydrogel was first evaluated by on-line tracking the dynamics curves using UV spectroscopy. Model drugs of phenformin for antidiabetes and doxorubicin for anticancer were selected to evaluate the drug carry and glucose/pH responsive drug release of the molecular hydrogel. The results showed the drug-loaded LMWG had good sustaining and long-lasting drug delivery in physiological or pathological environment.
- Tao, Ning,Li, Guotao,Liu, Miaochang,Gao, Wenxia,Wu, Huayue
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p. 3173 - 3180
(2017/05/08)
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- Simple and efficient Fmoc removal in ionic liquid
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A mild method for an efficient removal of the fluorenylmethoxycarbonyl (Fmoc) group in ionic liquid was developed. The combination of a weak base such as triethylamine and [Bmim][BF4] makes the entire system more efficient for the cleavage at room temperature of various amines and amino acid methyl esters in short reaction times. The procedure works well even in the case of N-Fmoc amino acids bearing acid-sensitive protecting groups and of N-alkylated amino acid methyl esters. The solvent-free condition provides a complementary method for Fmoc deprotection in solution phase peptide synthesis and modern organic synthesis.
- Di Gioia,Costanzo,De Nino,Maiuolo,Nardi,Olivito,Procopio
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p. 36482 - 36491
(2017/08/02)
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- Hydroxy-Directed Amidation of Carboxylic Acid Esters Using a Tantalum Alkoxide Catalyst
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We describe herein a new strategy for the chemoselective synthesis of amides by using a metal-catalyzed hydroxy-directed reaction. A hydroxy group located at the β-position of an ester group promoted the activation of a carbonyl group with a tantalum alkoxide catalyst followed by amidation reactions, leading to a wide variety of β-hydroxyamides with excellent chemeselectivity. The chemoselective amidation strategy can be extended to the catalytic synthesis of dipeptide derivatives, which remains challenging research subjects in modern organic synthesis.
- Tsuji, Hiroaki,Yamamoto, Hisashi
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supporting information
p. 14218 - 14221
(2016/11/13)
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- DELIVERY OF SMALL INTERFERING RNA AND MICRO RNA THROUGH NANOGELS CONTAINING HYDROPHOBIC PSEUDO-PEPTIDES
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Nanoscale, pH-responsive polycationic networks useful for the delivery of anionic biologic therapeutics and associated methods.
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Paragraph 65; 84
(2016/07/05)
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- GLYCOAMINO ACID AND USE THEREOF
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An object of the present invention is to provide glycoamino acid as an amino acid precursor with improved properties (particularly water-solubility, stability in water, bitter taste etc.). The present invention relates to a compound represented by the formula (I): wherein each symbol is as defined in the DESCRIPTION, or a salt thereof.
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Page/Page column 7
(2016/08/17)
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- Synthesis of 3-trimethylsiloxy-1-(furan-3-yl)butadiene and its reactions with dienophiles
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[Figure not available: see fulltext.] 3-Trimethylsilyloxy-1-(furan-3-yl)butadiene was synthesized and studied in reactions with 2,2-dimethyl-5-methylidene-1,3-dioxane-4,6-diones, 5-methylenepyrimidine-2,4,6-triones, as well as with imines. Reactions with dienophiles containing an exo-methylene double bond in the presence of L-proline occurred regio- and stereoselectively with the formation of 7-(furan-3-yl)spiro[5,5]undecane-1,5,9-triones or 7-(furan-3-yl)-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraones. The reaction of diene with methylene imine, obtained from L-phenylalanine methyl ester and formaldehyde, in the presence of Lewis acids led to the formation of 2-(furan-3-yl)piperidin-4-one or the product of ene reaction, methyl (2S)-2-{[(4E)-5-(furan-3-yl)-3-oxopent-4-en-1-yl]amino}-3-phenylpropanoate. The structures of three compounds were confirmed by X-ray structural analysis.
- Mironov, Maxim E.,Bagryanskaya, Irina Yu.,Shults, Elvira E.
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p. 364 - 373
(2017/03/16)
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- New functionalized 8-hydroxyquinoline-5-sulfonic acid mesoporous silica (HQS-SBA-15) as an efficient catalyst for the synthesis of 2-thiohydantoin derivatives
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Mesoporous silica SBA-15 functionalized with 8-hydroxyquinoline-5-sulfonic acid (HQS-SBA-15) was used as a new recyclable nanocatalyst for the one-pot synthesis of 2-thiohydantoin derivatives under solvent-free conditions. The catalyst exhibited excellent recyclability at least for 3 times with a high catalytic activity.
- Vavsari, Vaezeh Fathi,Ziarani, Ghodsi Mohammadi,Balalaie, Saeed,Latifi, Arezoo,Karimi, Mehdi,Badiei, Alireza
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supporting information
p. 5420 - 5426
(2016/08/05)
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