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https://read.qxmd.com/read/30876583/one-step-fabrication-of-cinchona-based-hybrid-monolithic-chiral-stationary-phases-via-photo-initiated-thiol-ene-polymerization-for-clc-enantioseparation
#1
Shujuan Ma, Yan Wang, Haiyang Zhang, Ya Li, Junjie Ou, Yinmao Wei, Mingliang Ye
Although various click polymerization reactions (thiol-ene, thiol-yne, thiol-Michael, thiol-epoxy and amine-epoxy) have been utilized to prepare either hybrid or organic monolithic columns with homogeneous network structures, there were few reports on fabrication of monolithic CSPs via click polymerization. Herein, a fast and robust approach was explored to fabricate cinchona-based monolithic hybrid CSPs via photo-initiated thiol-ene polymerization within 10 min in one step. A self-synthesized octakis(3-mercaptopropyl) octasilsesquioxane (POSS-SH) was polymerized with phenylisocyanate cinchonidine (PCD) and (+)-N,N'-diallyl-L-tartardiamide (DATDA) or 1,2,4-trivinylcyclohexane (TVCH)...
June 1, 2019: Talanta
https://read.qxmd.com/read/30867772/-erbb2-and-ptpn2-g-ene-copy-numbers-as-prognostic-factors-in-her2-positive-metastatic-breast-cancer-treated-with-trastuzumab
#2
Sander Ellegård, Cynthia Veenstra, Gizeh Pérez-Tenorio, Victor Fagerström, Jon Gårsjö, Krista Gert, Marie Sundquist, Annika Malmström, Sten Wingren, Nils O Elander, Anna-Lotta Hallbeck, Olle Stål
Trastuzumab has markedly improved the treatment and long-term prognosis of patients with HER2-positive breast cancer. A frequent clinical challenge in patients with relapsing and/or metastatic disease is de novo or acquired trastuzumab resistance, and to date no predictive biomarkers for palliative trastuzumab have been established. In the present study, the prognostic values of factors involved in the HER2-associated PI3K/Akt signalling pathway were explored. The first 46 consecutive patients treated at the Department of Oncology, Linköping University Hospital between 2000 and 2007 with trastuzumab for HER2-positive metastatic breast cancer were retrospectively included...
March 2019: Oncology Letters
https://read.qxmd.com/read/30848360/highly-efficient-synthesis-of-boldenone-from-androst-4-ene-3-17-dione-by-arthrobacter-simplex-and-pichia-pastoris-ordered-biotransformation
#3
Rui Tang, Yanbing Shen, Min Wang, Haijie Zhou, Yunqiu Zhao
Boldenone (BD) is an important steroid hormone drug which is the derivative of testosterone. In this study, an ordered biotransformation method was proposed employing Arthrobacter simplex and recombinant Pichia pastoris with 17β-hydroxysteroid dehydrogenase from Saccharomyces cerevisiae to produce BD from androst-4-ene-3,17-dione (AD) efficiently. To lower the oxidation towards BD in A. simplex, the transformation was conducted sequentially by C1,2 dehydrogenation in A. simplex and 17β-carbonyl reduction in recombinant P...
March 8, 2019: Bioprocess and Biosystems Engineering
https://read.qxmd.com/read/30813728/the-total-synthesis-of-chalcitrin
#4
Ming Yang, Fangjie Yin, Haruka Fujino, Scott A Snyder
The first total synthesis of the yellow pigment chalcitrin, a structurally distinct pulvinic acid dimer obtained from Chalciporous piperatus, has been achieved in 17 linear steps from commercially available materials. Key elements of the design include the use of a Au(I)-catalyzed Conia ene reaction and an N-heterocyclic carbene-mediated acyloin addition to rapidly fashion its unique polycyclic core, with the two high oxidation state sidechains introduced in a single step via a late-stage double Stille coupling...
February 27, 2019: Journal of the American Chemical Society
https://read.qxmd.com/read/30813030/facile-fabrication-of-cross-linked-fluorescent-organic-nanoparticles-with-aggregation-induced-emission-characteristic-via-the-thiol-ene-click-reaction-and-their-potential-for-biological-imaging
#5
Tianhao Wang, Meiying Liu, Dazhuang Xu, Junyu Chen, Qing Wan, Yuanqing Wen, Hongye Huang, Fengjie Deng, Xiaoyong Zhang, Yen Wei
Over the past several years, the biomedical applications of fluorescent organic nanoparticles (FONs) with aggregation-induced emission (AIE) feature have been extensively explored because the AIE-active FONs could effectively overcome the aggregation caused quenching (ACQ) effect of FONs based on conventional organic dyes. The development of novel methods for synthesis of AIE-active FONs plays a centre role for their biomedical applications. In this work, we reported a facile one-step thiol-ene click reaction for fabrication of AIE-active FONs through conjugation of acrylated PEG and AIE-active tetraphenylethylene (TPE) with two ene bonds using pentaerythritol tetra(3-mercaptopropionate) as the linkage...
May 2019: Materials Science & Engineering. C, Materials for Biological Applications
https://read.qxmd.com/read/30809359/f-10-binol-derived-chiral-phosphoric-acid-catalyzed-enantioselective-carbonyl-ene-reaction-theoretical-elucidation-of-stereochemical-outcomes
#6
Jun Kikuchi, Hiromu Aramaki, Hiroshi Okamoto, Masahiro Terada
An F10 BINOL-derived chiral phosphoric acid was shown to be an effective catalyst for an enantioselective carbonyl-ene reaction of 1,1-disubstituted olefins with ethyl glyoxylate as the common enophile. The perfluoro-binaphthyl skeleton is beneficial not only for adopting high catalytic activity but also for creating an effective chiral environment for enantioselective transformations. Indeed, the reaction afforded enantio-enriched homoallylic alcohols in high yields with high enantioselectivities. Theoretical studies identified that the multi-point C-H···O hydrogen bonds and the π interactions between the substrates and the 6-methoxy-2-naphthyl substituents at the 3,3'-positions of the F10 BINOL skeleton play a crucial role in determining the stereochemical outcomes...
February 7, 2019: Chemical Science
https://read.qxmd.com/read/30808174/intramolecular-imino-ene-reaction-of-azirines-regioselectivity-diastereoselectivity-and-computational-insights
#7
Mei-Hua Shen, Hong-Yu Qu, Ping Dai, Hao Zhou, Tai-Shang Liu, Xiaoguang Bao, Defeng Xu, Hua-Dong Xu
Intramolecular imino-ene reaction of 2H-aziridine has been studied experimentally and computationally, demonstrating that: 1) the concerted process takes place regioselectively on the alkene E-CH3 group; 2) the geometry of the N-linker impacts the reaction activation energy and diastereoselectivity significantly, with pyramidal alkyl amine as the linkage, exclusive cis-product is achieved; 3) when the reaction has to occur with the Z-CH3 group, the cis-diastereoselectivity is solely observed regardless the nature of the N-linkage...
February 27, 2019: Journal of Organic Chemistry
https://read.qxmd.com/read/30800457/crystal-structure-of-trans-bis-2-1-h-benzotriazol-1-yl-acetato-%C3%AE%C2%BA-o-bis-ethano-lamine-%C3%AE%C2%BA-2-n-o-copper-ii
#8
Guloy K Alieva, Jamshid M Ashurov, Shahnoza A Kadirova, Bakhtiyar T Ibragimov, Kasim A Zakhidov
The reaction of 2-(1 H -benzotriazol-1-yl)acetic acid (HBTA; C8 H7 N3 O2 ) and mono-ethano-lamine (MEA; C2 H7 NO) with CuCl2 ·2H2 O resulted in the formation of the title complex, [Cu(C8 H6 N3 O2 )2 (C2 H7 NO)2 ] or [Cu(BTA)2 (MEA)2 ]. Its asymmetric unit comprises one BTA anion coordin-ating to the Cu2+ cation (site symmetry ) through the carboxyl O atom, and one MEA ligand chelating the metal cation by two heteroatoms (O and N). The equatorial Cu-O and Cu-N bond lengths are similar at 2.029 (1) and 1.980 (2) Å, respectively, while the length of the axial Cu-O bond is considerably greater [2...
February 1, 2019: Acta Crystallographica. Section E, Crystallographic Communications
https://read.qxmd.com/read/30800447/crystal-structures-of-ircl-2-nhchph-dppm-c-n-2-dppm-%C3%AE%C2%BA-3-p-c-p-cl%C3%A2-5-5mecn-and-iri-nhchph-dppm-c-n-2-%C3%AE%C2%BA-2-p-c-dppm-%C3%AE%C2%BA-2-p-p-i-i-3-%C3%A2-0-5i-2-%C3%A2-meoh%C3%A2-0-5ch-2-cl-2-triazene-fragmentation-in-a-pcn-pincer-iridium-complex
#9
Bettina Pauer, Gabriel Julian Partl, Stefan Oberparleiter, Walter Schuh, Holger Kopacka, Klaus Wurst, Paul Peringer
The structure of [IrCl2 (C58 H51 N3 P4 )]Cl·5.5CH3 CN or [IrCl2 (NHCHPh)(((dppm)C(N2 dppm)) - κ 3 P,C,P )]Cl·5.5CH3 CN [ 3 , dppm = bis-(di-phenyl-phos-phino)methane; systematic name: di-chlorido(1,1,3,3,7,7,9,9-octa-phenyl-4,5-di-aza-1,3λ5 ,7λ4 ,9-tetra-phosphanona-3,5-dien-6-yl-κ2 P 1 , P 9 )-(phenyl-methanimine-κ N )iridium(III) chloride aceto-nitrile hemihendeca-solvate], resulting from an oxygen-mediated cleavage of a triazeneyl-idene-phospho-rane ligand producing a diazo-methyl-ene-phospho-rane and a nitrene moiety, which in turn rearrange via a Staudinger reaction and a 1,2-hydride shift to the first title complex, involves a six-coordinate IrIII complex cation coordinated by a facial PCP pincer ligand, a benzaldimine and two chlorido ligands...
February 1, 2019: Acta Crystallographica. Section E, Crystallographic Communications
https://read.qxmd.com/read/30799798/screening-of-no-inhibitor-release-activity-from-soft-coral-extracts-origin-palu-bay-central-sulawesi-indonesia
#10
Wendy Alexander Tanod, Uun Yanuhar, Maftuch, Masteria Yunovilsa Putra, Yenny Risjani
BACKGROUND: As a marine organism, soft corals can be utilized to be various bioactive substances, especially terpenoids and steroids. The soft corals family which produces bioactive generally come from clavulariidae, alcyoniidae, nephtheidae, xeniidae family. OBJECTIVE: to investigate the bioactivity of Nitric Oxide (NO) inhibitor release from soft coral crude extracts of Sinularia sp. (SCA), Nephthea sp. (SCB), Sarcophyton sp. (SCC), Sarcophyton sp. (SCD), Sinularia sp...
February 21, 2019: Anti-inflammatory & Anti-allergy Agents in Medicinal Chemistry
https://read.qxmd.com/read/30794421/photocatalyst-free-visible-light-photoredox-dearomatization-of-phenol-derivatives-containing-ketoximes-an-easy-access-to-spiropyrrolines
#11
Yongzhen Han, Yunhe Jin, Min Jiang, Haijun Yang, Hua Fu
A novel and simple visible-light photoredox intramolecular dearomatization of phenol derivatives containing ketoximes leading to spiropyrrolines has been developed. The protocol uses readily available 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the base and electron-donor, visible light as the light source, and the reaction was performed well at room temperature without need of a photocatalyst. Therefore, the present method should provide a useful strategy for synthesis of spiropyrrolines.
February 22, 2019: Organic Letters
https://read.qxmd.com/read/30794373/salt-free-reduction-of-transition-metal-complexes-by-bis-trimethylsilyl-cyclohexadiene-dihydropyrazine-and-4-4-bipyridinylidene-derivatives
#12
Hayato Tsurugi, Kazushi Mashima
Chemical reduction of transition metals provides the corresponding low-valent transition metal species as a key step for generating catalytically active species in metal-assisted organic transformations and is a fundamental unit reaction for preparing organometallic complexes. A variety of metal-based reductants, such as metal powders and organometallic reagents of alkali and alkaline-earth metals, have been developed to date to access low-valent metal species. During the reduction, however, reductant-derived metal salts are formed as reaction waste, some of which often interact with the reactive low-valent metal center, thereby disrupting the catalytic performance and hampering the isolation of organometallic complexes as a result of salt coordination to the coordinatively unsaturated vacant and active sites and the formation of thermally unstable ate complexes...
February 22, 2019: Accounts of Chemical Research
https://read.qxmd.com/read/30789707/dendron-polymer-conjugate-based-crosslinked-micelles-a-robust-and-versatile-nanosystem-for-targeted-delivery
#13
Filiz Calik, Aysun Degirmenci, Melike Eceoglu, Amitav Sanyal, Rana Sanyal
Among various nanomedicine platforms, biodegradable polymeric micelles offer a viable approach to targeted cancer therapy. Herein, we report fabrication of core-crosslinked micelles using dendron-polymer conjugates as building blocks. Hydrophobic polyester dendrons containing peripheral alkene groups are conjugated to a hydrophilic poly(ethylene glycol) based copolymer bearing activated ester groups for appending an amine-containing peptide based targeting group, namely, cRGDfK. Micellar constructs assembled in aqueous media were crosslinked using a tetra-thiol molecule via the photochemical thiol-ene reaction...
February 21, 2019: Bioconjugate Chemistry
https://read.qxmd.com/read/30786707/enantioselective-conia-ene-type-cyclizations-of-alkynyl-ketones-through-cooperative-action-of-b-c6f5-3-n-alkylamine-and-a-zn-based-catalyst
#14
Min Cao, Ahmet Yesilcimen, Masayuki Wasa
An efficient and highly enantioselective Conia-ene-type process has been developed. Reactions are catalyzed by a combination of B(C6F5)3, an N-alkylamine and a BOX-ZnI2 complex. Specifically, through cooperative action of B(C6F5)3 and amine, ketones with poorly acidic alpha-C-H bonds can be converted in situ to the corresponding enolates. Subsequent enantioselective cyclization involving a BOX-ZnI2-activated alkyne leads to the formation of various cyclopentenes in up to 99% yield and 99:1 er.
February 20, 2019: Journal of the American Chemical Society
https://read.qxmd.com/read/30753075/n-heterocyclic-olefin-catalysis-for-the-ring-opening-of-cyclic-amidine-compounds-a-pathway-to-the-synthesis-of-%C3%AE%C2%B5-caprolactam-and-%C3%AE-lactam-derived-amines
#15
Daniela Peixoto, Gabriela Malta, Hugo Cruz, Sónia Barroso, Ana Luisa Carvalho, Luisa Maria Ferreira, Paula Serio Branco
For the first time, 1,2-dimethyl-3-ethylimidazolium iodide (1a) catalyzes the ring opening of the bicyclic amidine system of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) or DBN (1,5-diazabicyclo[4.3.0]non-5-ene) on reaction with aldehydes. The mechanism here proposed involves a N-heterocyclic olefin (NHO) catalytic species that acts as a nucleophile to promote the cyclic amidine ring opening. The resulting ε-caprolactam and γ-lactam-derived imines were obtained in moderate to excellent yields (28-99%) and reduced to the corresponding amines by sodium borohydride...
February 12, 2019: Journal of Organic Chemistry
https://read.qxmd.com/read/30739756/stable-bond-polymeric-reversed-phase-weak-anion-exchange-mixed-mode-stationary-phases-obtained-by-simultaneous-functionalization-and-crosslinking-of-a-poly-3-mercaptopropyl-methylsiloxane-film-on-vinyl-silica-via-thiol-ene-double-click-reaction
#16
Stefanie Bäurer, Aleksandra Zimmermann, Ulrich Woiwode, Orlando L Sánchez-Muñoz, Markus Kramer, Jeannie Horak, Wolfgang Lindner, Wolfgang Bicker, Michael Lämmerhofer
A polymeric reversed-phase/weak anion exchange (Poly-RP/WAX) mixed-mode stationary phase has been prepared by coating of a poly(3-mercaptopropyl)methylsiloxane film on vinyl-modified silica (100 Å, 5 μm) and simultaneous in situ functionalization with N-(10-undecenoyl)-3-aminoquinuclidine as well as crosslinking to the vinyl silica surface by solventless thiol-ene double click reaction. Such bonding chemistry showed greatly enhanced stability compared to brush-type analogs with bifunctional siloxane bonding to silica...
February 1, 2019: Journal of Chromatography. A
https://read.qxmd.com/read/30736414/gelatin-based-hydrogels-through-homobifunctional-triazolinediones-targeting-tyrosine-residues
#17
Roberto Guizzardi, Luca Vaghi, Marcello Marelli, Antonino Natalello, Ivan Andreosso, Antonio Papagni, Laura Cipolla
Gelatin is a biopolymer with interesting properties that can be useful for biomaterial design for different applications such as drug delivery systems, or 3D scaffolds for tissue engineering. However, gelatin suffers from poor mechanical stability at physiological temperature, hence methods for improving its properties are highly desirable. In the present work, a new chemical cross-linking strategy based on triazolinedione ene-type chemistry towards stable hydrogel is proposed. Two different homobifunctional 1,2,4-triazoline-3,5(4 H )-diones, namely 4,4'-hexane-1,6-diylbis(3 H -1,2,4-triazoline-3,5(4 H )-dione) 1 and 4,4'-[methylenebis(4,1-phenylene)] bis (3 H -1,2,4-triazoline-3,5(4 H )-dione) 2 were used as cross-linkers in different ratio to tyrosine residues in gelatin...
February 7, 2019: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://read.qxmd.com/read/30723042/fluorogenic-approach-to-evaluating-prodrug-hydrolysis-and-stability-in-live-cells
#18
Xin Chen, Yunzhen Xu, Xiaoxu Li, Shiqi Liao
Fluorescein diester which is conjugated with cell membrane permeable Arg9 peptide was proposed as probe for ester prodrug stability and drug release study in living cells. α-Amino protected d-Val and l-Ala which bear differently hindered side chains were used to afford model diesters of 5-maleimide-fluorescein. Such fluorescein diesters were further conjugated with a Cys containing cell membrane permeable Arg9 peptide via thiol-ene crosslink reaction. The resulted conjugates of fluorescein diester and Arg9 peptide were purified with HPLC and characterized with MALDI-TOF MS...
January 29, 2019: Bioorganic & Medicinal Chemistry
https://read.qxmd.com/read/30715866/antioxidative-maillard-reaction-products-generated-in-processed-aged-garlic-extract
#19
Junichiro Wakamatsu, Timo D Stark, Thomas Hofmann
A powder formulation of aged garlic extract was heated at 100 oC for one day to obtain higher antioxidant activity determined with ABTS radical scavenging (ARS) and ORAC assays. Activity-guided fractionation afforded 12 new in vitro antioxidative Maillard-type products (Figure 1), α-[(2-formyl-5-hydroxymethyl)pyrrol-1-yl]arginine (3), 4-[7-hydroxy-6-(hydroxymethyl)-7,8-dihydro-6H-pyrano[2,3-b] pyrazine-3-yl]butane-1,2,3-triol (4) and 4-[6-(1,2-dihydroxyethyl)-6,7-dihydro-furo[2,3-b]pyrazin-3-yl]-butane-1,2,3-triol (5), α-[(2-formyl-5-hydroxymethyl)-pyrrol-1-yl] aspartic acid (12), 1-[5-(1,2-dihydroxyethyl)-2-oxotetrahydrofuran-3-yl]-5-(hydroxymethyl)-1H-pyrrole-2-carbaldehyde (14), 4-(6-ethyl-2-pyrazinyl)-1,2,3-butanetriol (17), α-[(2-formyl-5-hydroxymethyl)pyrrol-1-yl] glutamic acid (19), (S)-1-[(5-hydroxymethyl)furan-2-yl]methyl]-5-oxopyrrolidine-2-carboxylic acid (20), 3-hydroxy-1H-[{5-(hydroxymethyl)furan-2-yl}methyl]-2,5-dioxo-3-pyrrolidine acetic acid (21), (E)-4-(5-methylpyrazin-2-yl)but-3-ene-7,2-diol (23), 4-acetyl-6-(hydroxymethyl)picolinic acid (24), (E)-4-(6-methylpyrazin-2-yl)but-3-ene-1,2-diol (26) and 14 known compounds (Figure 1, 1, 2, 6-11, 13, 15, 16, 18, 22 and 25) which were characterized via 1D/2D-NMR, CD spectroscopy, and mass spectrometry...
February 4, 2019: Journal of Agricultural and Food Chemistry
https://read.qxmd.com/read/30713738/crystal-structures-of-two-pcn-pincer-iridium-complexes-and-one-pcp-pincer-carbodi-phospho-rane-iridium-inter-mediate-substitution-of-one-phosphine-moiety-of-a-carbodi-phospho-rane-by-an-organic-azide
#20
Gabriel Julian Partl, Felix Nussbaumer, Walter Schuh, Holger Kopacka, Klaus Wurst, Paul Peringer
The structure of [Ir{(4-Cl-C6 H4 N3 )C(dppm)-κ3 P , C , N }(dppm-κ2 P , P ')]Cl·1.5CH2 Cl2 ·0.5C7 H8 (C57 H48 Cl2 IrN3 P4 ·1.5CH2 Cl2 ·0.5C7 H8 ) ( 2 ), dppm = bis-(di-phenyl-phosphino)methane {systematic name: [7-(4-chloro-phen-yl)-1,1,3,3-tetra-phenyl-5,6,7-tri-aza-κ N 7 -1,3λ4 -diphospha-κ P 1 -hepta-4,6-dien-4-yl][methyl-ene-bis(di-phenyl-phosphine)-κ2 P , P ']iridium(I) chloride-di-chloro-methane-toluene (2/3/1)}, resulting from the reaction of [IrClH{C(dppm)2 -κ3 P , C , P )(MeCN)]Cl ( 1a ) with 1-azido-4-chloro-benzene, shows a monocationic five-coordinate IrI complex with a distorted trigonal-bipyramidal geometry...
January 1, 2019: Acta Crystallographica. Section E, Crystallographic Communications
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