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Organic & Biomolecular Chemistry

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https://www.readbyqxmd.com/read/28221392/a-4-5-quinolimide-based-fluorescent-sensor-for-the-turn-on-detection-of-cd-2-with-live-cell-imaging
#1
Yu Zhang, Xiangfeng Guo, Mengmeng Zheng, Rui Yang, Hongming Yang, Lihua Jia, Mengmeng Yang
A 4,5-quinolimide derivative, BNA, bearing the amide-DPA receptor, was synthesized as a turn-on fluorescent sensor for Cd(2+). Under physiological conditions, BNA could distinguish Cd(2+) from Zn(2+), showing turn-on fluorescence behaviour and an increased fluorescence lifetime. BNA and Cd(2+) formed a 1 : 1 stoichiometric complex, and the detection limit was measured to be as low as 11 nM. Furthermore, BNA was utilized for fluorescence imaging of Cd(2+) in live cells. To the best of our knowledge, it is the first 4,5-quinolimide-based sensor for the detection of metal ions...
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28221391/intramolecular-minisci-acylation-under-silver-free-neutral-conditions-for-the-synthesis-of-azafluorenones-and-fluorenones
#2
Joydev K Laha, Ketul V Patel, Gurudutt Dubey, Krupal P Jethava
Despite its synthetic potential, intramolecular acylation by the Minisci reaction remains unexplored. The development of a new intramolecular Minisci acylation under silver-free neutral conditions providing access to azafluorenones and fluorenones is described. Distinct from the current literature known approaches for Minisci acylation, the report described herein features a method that: (a) avoids the use of silver that is invariably used in Minisci acylation, (b) does not require any acidic conditions for the activation of pyridines, and...
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28221388/synthesis-of-c6-modified-%C3%AE-c-galcer-analogues-as-mouse-and-human-inkt-cell-agonists
#3
Joren Guillaume, Toshiyuki Seki, Tine Decruy, Koen Venken, Dirk Elewaut, Moriya Tsuji, Serge Van Calenbergh
α-GalCer analogues that combine known Th1 polarizing C6''-modifications with a C-glycosidic linkage were synthesized. We employed a protecting group strategy that allowed the preparation of both saturated and unsaturated derivatives with variable C6''-substituents. Selected analogues demonstrate promising activity in mice. Interestingly, the introduction of a 6''-O-pyridinylcarbamoyl substituent to α-C-GalCer restores its antigenicity in human iNKT cells.
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28221380/spatial-mismatch-non-additive-binding-energies-and-selectivity-in-supramolecular-complexes
#4
REVIEW
Hans-Jörg Schneider
The consequences of spatial mismatch between a receptor and ligand on affinity and selectivity of supramolecular complexes are illustrated with several examples. Conformationally rigid complexes and shorter-range non-covalent forces are characterized by large affinity changes, in contrast to more flexible systems. In the most frequent complexes with several spaciously separated binding sites, the additivity of binding energies and the correlation between affinity and selectivity is often lost by partial mismatch...
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28221378/characterization-of-drug-encapsulation-and-retention-in-archaea-inspired-tetraether-liposomes
#5
Geoffray Leriche, Jessica L Cifelli, Kevin C Sibucao, Joseph P Patterson, Takaoki Koyanagi, Nathan C Gianneschi, Jerry Yang
The passive leakage of small molecules across membranes is a major limitation of liposomal drug formulations. Here, we evaluate the leakage of 3 clinically used chemotherapeutic agents (cytarabine, methotrexate and vincristine) encapsulated in liposomes comprised of a synthetic, archaea-inspired, membrane-spanning tetraether lipid. Liposomes comprised of the pure tetraether lipid exhibited superior retention of both a neutrally and positively charged drug (up to an ∼9-fold decrease in the rate of drug leakage) compared to liposomes formed from a commercial diacyl lipid, while exhibiting a similar retention of a negatively charged drug that did not appreciably leak from either type of liposome...
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28220178/a-photo-degradable-supramolecular-hydrogel-for-selective-delivery-of-microrna-into-3d-cultured-cells
#6
Zhengquan Zhou, Qikun Yi, Tingting Xia, Wencui Yin, Adnan A Kadi, Jinbo Li, Yan Zhang
Multi-functional supramolecular hydrogels have emerged as smart biomaterials for diverse biomedical applications. Here we report a multi-functional supramolecular hydrogel formed by the conjugate of the bioactive GRGDS peptide with biaryltetrazole that is the substrate of photo-click reaction. The hydrogel was used as a biocompatible matrix to encapsulate live cells for 3D culture. The presence of the RGD epitope in the hydrogelator enhanced the interaction of the nanofiber with integrin over-expressing cells, which resulted in the selective enhancement in the miRNA delivery into the encapsulated U87 cells...
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28220174/discovery-of-s-3-hydroxyblebbistatin-and-s-3-aminoblebbistatin-polar-myosin-ii-inhibitors-with-superior-research-tool-properties
#7
Sigrid Verhasselt, Bart I Roman, Olivier De Wever, Kristof Van Hecke, Rik Van Deun, Marc E Bracke, Christian V Stevens
In search of myosin II inhibitors with superior research tool properties, a chemical optimization campaign of the blebbistatin scaffold was conducted in this paper. (S)-Blebbistatin is the best known small-molecule inhibitor of myosin II ATPase activity. Unfortunately, as a research tool this compound has several deficiencies: it is photolabile and (photo)toxic, has low water solubility, and its (fluorescent) precipitates interfere in (fluorescence) readouts. In view of obtaining tool compounds with improved properties, both enantiomers of a series of D-ring modified polar analogs were prepared...
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28220169/mg-ome-2-promoted-allylic-isomerization-of-%C3%AE-hydroxy-%C3%AE-%C3%AE-alkenoic-esters-to-synthesize-%C3%AE-ketone-esters
#8
Luhao Lai, A-Ni Li, Jiawei Zhou, Yarong Guo, Li Lin, Wei Chen, Rui Wang
This work concerns the Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,β-alkenoic esters with TMEDA as an additive. The isomerization proceeded under mild conditions and afforded γ-keto esters in high yield (up to 96%) within 2 h. Both (Z)- and (E)-γ-hydroxy-α,β-alkenoic esters were tolerated under the reaction conditions. This transformation involves the in situ formation of a dienolate intermediate from the easily accessible γ-hydroxy-α,β-alkenoic ester. The in situ generated dienolate can react with benzaldehyde and undergo a practical, useful tandem allylic isomerization-Aldol reaction to afford more functionalized compounds...
February 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28217770/post-synthetic-conversion-of-5-pivaloyloxymethyluridine-present-in-a-support-bound-rna-oligomer-into-biologically-relevant-derivatives-of-5-methyluridine
#9
Karolina Bartosik, Elzbieta Sochacka, Grazyna Leszczynska
A post-synthetic reaction of 5-pivaloyloxymethyluridine (present in a support-bound RNA oligomer) with various nucleophilic reagents furnished efficiently the corresponding products bearing one of the tRNA wobble 5-methyluridines (mnm(5)U, cmnm(5)U, τm(5)U, nm(5)U, inm(5)U or cnm(5)U). The syntheses of oligoribonucleotides modified with inm(5)U and cnm(5)U are reported for the first time.
February 20, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28211926/protecting-group-free-synthesis-of-glycosyl-thiols-from-reducing-sugars-in-water-application-to-the-production-of-n-glycan-glycoconjugates
#10
S R Alexander, D Lim, Z Amso, M A Brimble, A J Fairbanks
Glycosyl thiols may be accessed from the corresponding reducing sugars in water without recourse to any sugar projecting groups by way of a DMC mediated reaction with thioacetic acid in the presence of base, and hydrolysis of the anomeric thioacetate. Glycosyl thiols produced by this method may be used to access glycoconjugates, such as glycopeptides by use of the thiol-ene click reaction.
February 17, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28210740/catalyst-free-synthesis-of-%C3%AE-fluoro-%C3%AE-hydroxy-ketones-%C3%AE-fluoro-ynols-via-electrophilic-fluorination-of-tertiary-propargyl-alcohols-using-selectfluor%C3%A2-f-teda-bf4
#11
Naganaboina Naveen, Rengarajan Balamurugan
A facile method for the synthesis of α-fluoro-β-hydroxy ketones/α-fluoro-ynols from tertiary propargyl alcohols under electrophilic fluorination conditions using F-TEDA-BF4 has been presented. The products bear pharmaceutically important α-fluoro ketone, gem-diaryl and fluorohydrin moieties in the same molecule. Interestingly, this catalyst free protocol results in monofluorination.
February 17, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28210736/one-pot-construction-of-sterically-challenging-and-diverse-polyarylphenols-via-transition-metal-free-benzannulation-and-their-potent-in-vitro-antioxidant-activity
#12
Shizuka Mei Bautista Maezono, Tej Narayan Poudel, Yong Rok Lee
This paper reports the novel and efficient one-pot synthesis of highly functionalized polyarylphenols from readily available 1,3-diarylpropan-2-ones and chalcones or cinnamaldehyde derivatives via benzannulation under transition-metal-free and aerobic conditions. This benzannulation proceeds through cascade Michael addition/intramolecular aldol/tautomerization/oxidation. This protocol produces various tetra- and tri-aryl substituted phenols in moderate to good yield. The synthesized compounds exhibited potent antioxidant activities compared to the standard BHT...
February 17, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28210722/synthesis-radio-synthesis-and-in-vitro-evaluation-of-terminally-fluorinated-derivatives-of-hu-210-and-hu-211-as-novel-candidate-pet-tracers
#13
Chiara Zanato, Alessia Pelagalli, Katie F M Marwick, Monica Piras, Sergio Dall'Angelo, Andrea Spinaci, Roger G Pertwee, David J A Wyllie, Giles E Hardingham, Matteo Zanda
We report the synthesis of terminally fluorinated HU-210 and HU-211 analogues (HU-210F and HU-211F, respectively) and their biological evaluation as ligands of cannabinoid receptors (CB1 and CB2) and N-methyl d-aspartate receptor (NMDAR). [(18)F]-labelled HU-210F was radiosynthesised from the bromo-substituted precursor. In vitro assays showed that both HU-210F and HU-211F retain the potent pharmacological profile of HU-210 and HU-211, suggesting that [(18)F]-radiolabelled HU-210F and HU-211F could have potential as PET tracers for in vivo imaging...
February 17, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28210721/3-pyrene-modified-unlocked-nucleic-acids-synthesis-fluorescence-properties-and-a-surprising-stabilization-effect-on-duplexes-and-triplexes
#14
Maria Ejlersen, Niels Langkjær, Jesper Wengel
Efficient synthesis of a new 3'-O-amino-UNA monomer was developed as a scaffold for further functionalization and incorporation into oligonucleotides (ONs). Pyrene-functionalized 3'-O-amino-UNA was incorporated one, two or three times into 21-mer DNA and 2'-O-Me-RNA ONs. Duplex melting temperatures, circular dichroism (CD) spectra, steady-state fluorescence emission spectra, UV/Vis absorption spectra and triplex melting temperatures were measured for the modified duplexes. The presence of the pyrene-modified UNA monomer lead to a surprising and unprecedented thermal stabilization of especially DNA:DNA duplexes when compared to the corresponding unmodified DNA:DNA duplexes...
February 17, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28203674/cobalt-salt-catalyzed-carbocyclization-reactions-of-%C3%AE-bromo-n-phenylacetamide-derivatives
#15
Yi-Chen Cheng, Ying-Yu Chen, Che-Ping Chuang
An efficient and low-cost method for the synthesis of 4-substituted quinolin-2-(1H)-ones has been developed. In the presence of TBHP, the cobalt(ii)-catalyzed carbocyclization reactions of arylethenyl substituted α-bromo-N-phenylacetamides, involving sequential 6-exo-trig radical cyclization, t-butylperoxy radical cross-coupling reaction and the base-promoted ionic Kornblum-DeLaMare reaction, produced 4-benzoylquinolin-2-(1H)-ones. A variety of useful functional groups such as methoxy, fluoro, chloro, bromo, methoxycarbonyl, and cyano groups, are compatible with the reaction conditions...
February 16, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28203673/amphipathic-guanidine-embedded-glyoxamide-based-peptidomimetics-as-novel-antibacterial-agents-and-biofilm-disruptors
#16
Shashidhar Nizalapur, Onder Kimyon, Eugene Yee, Kitty Ho, Thomas Berry, Mike Manefield, Charles G Cranfield, Mark Willcox, David StC Black, Naresh Kumar
Antimicrobial resistance in bacteria is becoming increasingly prevalent, posing a critical challenge to global health. Bacterial biofilm formation is a common resistance mechanism that reduces the effectiveness of antibiotics. Thus, the development of compounds that can disrupt bacterial biofilms is a potential strategy to combat antimicrobial resistance. We report herein the synthesis of amphipathic guanidine-embedded glyoxamide-based peptidomimetics via ring-opening reactions of N-naphthoylisatins with amines and amino acids...
February 16, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28198907/enantioselective-synthesis-of-spiro-%C3%AE-butyrolactones-by-n-heterocyclic-carbene-nhc-catalyzed-formal-3-2-annulation-of-enals-with-3-hydroxy-oxindoles
#17
Subrata Mukherjee, Sumi Joseph, Anup Bhunia, Rajesh G Gonnade, Santhivardhana Reddy Yetra, Akkattu T Biju
The N-heterocyclic carbene (NHC)-catalyzed enantioselective formal [3 + 2] annulation of α,β-unsaturated aldehydes with 3-hydroxy oxindoles is presented. Under oxidative conditions using the bisquinone oxidant, the reaction resulted in the synthesis of spiro γ-butyrolactones in moderate to good yields, enantioselectivity and diastereoselectivity. The reaction likely proceeds via the generation of the NHC-bound α,β-unsaturated acylazolium intermediate from enals, which was intercepted by the dioxindoles in a formal [3 + 2] pathway to form the spirocyclic compounds...
February 15, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28198903/a-stereoselective-synthesis-of-e-or-z-%C3%AE-arylvinyl-halides-via-a-borylative-coupling-halodeborylation-protocol
#18
Jakub Szyling, Adrian Franczyk, Piotr Pawluć, Bogdan Marciniec, Jędrzej Walkowiak
A new stereoselective method for the synthesis of (E)-β-arylvinyl iodides and (E)- or (Z)-β-arylvinyl bromides from styrenes and vinyl boronates on the basis of a one-pot procedure via borylative coupling/halodeborylation is reported. Depending on the halogenating agent as well as the mode of the halodeborylation reaction, (E) or (Z) isomers are selectively formed.
February 15, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28197609/computational-studies-on-the-cyclization-of-squalene-to-the-steroids-and-hopenes
#19
REVIEW
B Andes Hess
A review of computational studies of the related biosyntheses of steroids and hopenes reported during the last two decades is presented. Computations in the gas phase and those that include the enzyme are covered. Based on the numerical results conclusions have been drawn about the biosynthetic mechansims of these all important biological reactions.
February 15, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28195591/correction-synthesis-and-immunological-evaluation-of-muc1-glycopeptide-conjugates-bearing-n-acetyl-modified-stn-derivatives-as-anticancer-vaccines
#20
An Xiao, Xiu-Jing Zheng, Chengcheng Song, Yue Gui, Chang-Xin Huo, Xin-Shan Ye
Correction for 'Synthesis and immunological evaluation of MUC1 glycopeptide conjugates bearing N-acetyl modified STn derivatives as anticancer vaccines' by An Xiao et al., Org. Biomol. Chem., 2016, 14, 7226-7237.
February 14, 2017: Organic & Biomolecular Chemistry
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