It is an open “secret” that commercial PEG‐amine is of unreliable quality, for which we ascribe to both flawed manufacturing protocols and storage stability issues. In addition, conventional PEG functionalization relies on esterification and etherification steps, suffering from incomplete conversion, harsh reaction condition, and functional group incompatibility. To solve these practical challenges, we propose an efficient strategy for PEG functionalization through carbamate linkages. By finely tuning...
Wed Jul 08, 2020 20:19
Herein, we report that highly chemoselective and enantioselective reduction of 2‐vinyl‐substituted pyridines has been achieved for the first time. The reaction, which uses chiral spiro‐bicyclic bisboranes as catalysts and HBpin and an acidic amide as reducing reagents, proceeds via a cascade process involving 1,4‐hydroboration followed by transfer hydrogenation of a dihydropyridine intermediate. The retained double bond in the reduction products permits their conversion to natural products and other...
Wed Jul 08, 2020 19:25
Luminescent Eu(II) complexes with characteristic 5d‐4f transition have potential applications in many fields. However, their instability in ambient conditions impedes further exploration and application. Herein, we report two new Eu(II) complexes, bis[hydrotris(3‐trifluoromethylpyrazolyl)borate]europium(II) ( Eu‐1 ) and bis[hydrotris(3‐methylpyrazolyl)borate]europium(II) ( Eu‐2 ). Intriguingly, the blue emissive Eu‐1 showed high air stability arising from fluorine protection and close molecular...
Wed Jul 08, 2020 18:47
trans‐Selective Aryldifluoroalkylation of Endocyclic Enecarbamates and Enamides via Nickel Catalysis
2‐Pyrroline and 2‐azetine are useful synthons for the synthesis of pyrrolidines and azetidines that widely exist in natural products, pharmaceuticals, and agrochemicals. But efficient methods for dicarbofuntionalization of these cyclic alkenes are limited. Particularly, the dicarbofunctionalization of endocyclic enecarbamates to achieve fluorinated compounds remains an unsolved issue, despite of the wide applications of organofluorinated molecules in life and materials science. Here, we report a...
Wed Jul 08, 2020 17:44
Combinatorial antitumor therapies using different chemodrug combo or chemo/gene agent combo emerge as promising ways to overcome the drug resistance, a major cause for the failure of cancer treatment. However, dramatic pharmacokinetic differences of adopted drugs greatly impede the combinatorial antitumor practices, raising the great demand of developing appropriate drug delivery systems (DDSs) for tumor treatment. By employing fluorescent dithiomaleimide (DTM) as a linker, herein, we conjugate two...
Wed Jul 08, 2020 16:52
Serious diffusional limitations are frequently observed for the conversion of bulky molecules over conventional zeolite Beta crystals, which invoke for hierarchical structure to improve the mass transportation property and the accessibility to reactive sites. Zeolite single crystals with intracrystalline hierarchical porosity at macro‐, meso‐ and micro‐length scales is of great significance and provides the best solution . However, the construction of large zeolite Beta single crystals with such...
Wed Jul 08, 2020 16:50
Influenza meets its match : Based on the principle of topology matching, a potent nanoparticle‐based inhibitor for influenza A was designed that shows heteromultivalent inhibition of the receptor‐binding viral proteins. This inhibitor is capable of neutralizing influenza A virus extracellularly and blocking its interaction with the host cell receptors. This principle could potentially also be applied to the inhibition of other viruses with spiky surfaces. Abstract In this study, we demonstrate...
Wed Jul 08, 2020 12:31
Draw me a CKA : the radical ring‐opening polymerization of model CKA monomers was investigated using quantum calculations and kinetic modeling. The results were supported by a detailed experimental study. The new proposed methodology allows to predict in silico the efficiency of CKA monomers to prepare polyester through a radical pathway. Abstract Radical ring‐opening polymerization (rROP) of cyclic ketene acetals (CKAs) combines the advantages of both ring‐opening polymerization and radical...
Wed Jul 08, 2020 12:23
Supported rhodium catalysts anchored to mesoporous silica in three different locations demonstrate optimal tethering location, allowing for deployment in a fixed bed flow reactor for enantio‐ and regioselective C−H functionalization. Tuning silica particle size/shape enhances reactivity and the catalyst immobilization methodology is widely applicable. Abstract Herein we demonstrate a packed bed flow reactor capable of achieving highly regio‐ and stereoselective C−H functionalization reactions...
Wed Jul 08, 2020 12:19
A site‐selective late‐stage peptide modification and macrocyclization strategy by means of palladium‐catalyzed C(sp2)−H olefination of tryptophan residues at the C2 and C4 positions has been developed. TIPS=triisopropylsilyl; Tf=trifluorosulfonamide. Abstract Transition‐metal‐catalyzed C−H activation has shown potential in the functionalization of peptides with expanded structural diversity. Herein, the development of late‐stage peptide macrocyclization methods by palladium‐catalyzed site‐selective...
Wed Jul 08, 2020 12:19
Same NAT2, new substr8 : NAT2 has been classified as an arylamine N‐acetyltransferase that mainly converts aromatic amines, hydroxylamines, and hydrazines. Through a combination of metabolomics, chemical synthesis, and mass spectrometry it is demonstrated that unknown endogenous, aliphatic metabolites, and aliphatic amine‐containing commonly used drugs also act as substrates for NAT2. Abstract N‐Acetyltransferases play critical roles in the deactivation and clearance of xenobiotics, including...
Wed Jul 08, 2020 12:18
Bromine in a bottle : To accept the insertion of Br2, the bowl‐type structure of dodecavanadate was rearranged. Owing to the unique electrophilic feature of the bowl inside, Br2 was polarized such that it could be observed by IR spectroscopy. Polarized Br2 in a dodecavanadate bowl acted as an electrophilic reagent to achieve selective bromination of propane, n‐butane, or n‐pentane. Abstract Dodecavanadate, [V12O32]4− (V12), possesses a 4.4 Å cavity entrance, and the cavity shows unique...
Wed Jul 08, 2020 12:18
Electrifying : Reported herein is an electrochemical approach for the oxidative generation of benzynes (cyclohexyne) and its successful merging with chiral primary aminocatalysis, formulating the first catalytic asymmetric enamine–benzyne (cyclohexyne) coupling reaction. Cobalt acetate stabilizes the in situ generated arynes and facilitates its coupling with an enamine. This protocol provides a method for the construction of diverse α‐aryl (α‐cyclohexenyl) quaternary carbon stereogenic centers...
Wed Jul 08, 2020 12:18
An eight‐vertex Zintl anion with an arachno‐type structure obtained from solution, (Sn5Sb3)3− (1 ), was synthesized as its [ n Bu4P]+ salt. Calculations on the isoelectronic series (Sn x Sb8−x )2−x (x =0–8) were performed to investigate possible alternative structures of 1 , which revealed that the preferred structures of the isomers vary significantly with composition, independent of electron count. Abstract The pseudo‐element concept, in its most general formulation,...
Wed Jul 08, 2020 12:15
Abstract Actigraphy is a cost‐efficient method to estimate sleep–wake patterns over long periods in natural settings. However, the lack of methodological standards in actigraphy research complicates the generalization of outcomes. A rapidly growing methodological diversity is visible in the field, which increasingly necessitates the detailed reporting of methodology. We address this problem and evaluate the current state of the art and recent methodological developments in actigraphy reporting with...
Wed Jul 08, 2020 11:35
Summary Attitudes and expectations of people towards their lives are essential to future health outcomes. Growing evidence has linked dispositional optimism to beneficial health outcomes, such as exceptional longevity, healthy aging and better sleep quality. We describe the association between dispositional optimism and chronic insomnia, considering potential mediators, in the Austrian Sleep Survey (N = 1,004), a population‐based cross‐sectional study conducted in 2017. Optimism was measured using...
Wed Jul 08, 2020 11:19
Abstract Background The Milan system for Reporting Salivary Gland Cytopathology (MSRSGC) was published in 2018. Since then, many authors have published their institutional experience by retrospectively assigning salivary gland fine‐needle aspiration cases to each of the MSRSGC categories and calculated their risk of malignancy (ROM) accordingly. Methods We reviewed all published articles available online in English that used the MSRSGC since or near its publication. We calculated the risk...
Wed Jul 08, 2020 21:14
Journal of Cutaneous Medicine and Surgery, Ahead of Print.
Wed Jul 08, 2020 10:36
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