Latest ArticlesSimple saccharides have a variety of biological functions, but their structural diversity and inherent structural features pose a major challenge for rapid analysis. In this work, we developed a derivative-free and ion mobility-free method for the rapid analysis of monosaccharides and disaccharides using paper spray tandem mass spectrometry. Trimeric cluster ions consisting of saccharide analytes, ligands and transition metal ions are used as precursor ions. We defined the R-value as the ratio of the intensity of the product ion that loses one molecule of ligand over the intensity of the product ion that loses one molecule of saccharide via collision induced dissociation (CID). The species and conformation of simple saccharides can be easily differentiated by calculating this R-value. With the capability of directly analyzing clinical samples using paper spray ionization, our method can be used to rapidly quantify the molar ratio of galactose to glucose in dried plasma samples to aid in the diagnosis of galactosemia. The analytical strategy provided herein has good potential to be applied to a wide range of saccharide analysis applications in the future.
The utilization of readily available amino acids, which is not only an oxygen nucleophile but also a nitrogen nucleophile, in palladium-catalyzed allylic substitution is realized under mild conditions. The chemoselectivity and multiple allylation are controlled by adjusting the reaction conditions. This represents the first example of this convenient access to valuable N,O-diallylated amino acids. Under the title conditions, a range of amino acids (α-, β-, γ-) and dipeptides can be readily converted in to the corresponding allylic products with excellent yields (67 examples, up to 99% yield) as well as good functional group tolerance.
A new method for the preparation of fluoroalkylthioethers including trifluoromethylthioether and difluoromethylthioether by iridium(Ⅰ)-catalyzed deoxgenation of fluoroalkylsulfoxides with dimethyl diazomalonate was developed. In the reaction system, dimethyl diazomalonate was used as reducing reagent and the corresponding fluoroalkylthioethers were produced through oxygen atom transfer from fluoroalkylsulfoxides to diazomalonate. The protocol featuring effective oxygen atom transfer, mild reaction conditions and good functional groups tolerance offers an alternative strategy for the synthesis of fluoroalkylthioethers.
Although multitudinous nanoscale drug-delivery systems (DDSs) have been recommended to improve anti-ulcerative colitis (UC) outcomes, to enhance the mucoadhesion of nanosystems on the colon and specifically release the loaded drugs in response to the colon micro-environment would be critical factors. The application of curcumin (Cur), an acknowledged anti-UC phytochemical compound, for UC therapy requires more efficient nano-carriers to improve its therapeutic outcome. Herein, we developed the colon-targeted nano-micelles with mucoadhesive effect and Azo reductase-triggered drug release profiles for Cur delivery in UC treatment. Specifically, the amphiphilic block polymer containing the Azo-reductase sensitive linkage (PEG-Azo-PLGA), and catechol-modified TPGS (Cat-TPGS) were synthesized respectively. Based on the self-assembly of the mixed polymers, Cur-micelles (142.7 ± 1.7 nm of average size, 72.36% ± 1.54% of DEE) were obtained. Interestingly, the Cur-micelles exhibited the Azo-reductase sensitive particle dissociation and drug release, the enhanced cellular uptake and the prolonged retention on colonic mucosa, mediated by the strong mucoadhesion of catechol structure. Ultimately, Cur-micelles significantly mitigated colitis symptoms and accelerated colitis repair in DSS-treated mice by regulating the intestinal flora and the levels of pro-inflammatory factors (MPO, IL-6, IL-1β, and TNF-α) related to TLR4/MyD88/NF-κB signaling pathway. This work provides an effective drug delivery strategy for anti-UC drugs by oral administration.
A visible-light-mediated reaction of indole derivatives employing arylsulfonyl chlorides as sulfonyl surrogates has been developed, which proceeds via the sequence of reduction of sulfonyl chloride, sulfonylation, and intramolecular cyclization. This mild protocol transforms a diverse array of indole tethered alkenes and simple sulfonyl chlorides into highly valuable functionalized tetrahydrocarbazoles in good yields. This reaction is also suitable for gram-scale synthesis, which provides an efficient and green access to multi-substituted tetrahydrocarbazoles.
Herein, we adopt a simple supramolecular strategy to effectively control the tautomerism of ureidopyrimidinone (UPy) moiety and ultimately realize the complete arrangement of enol configuration. The obtained UPy derivatives containing self-complementary quadruple hydrogen bonding interactions can spontaneously self-assemble towards the formation of well-controlled, self-organized supramolecular nanostructure morphologies in both chloroform and water. The resulting aggregates had been fully characterized by various spectroscopy (absorption, emission) and microscopy (TEM, SEM and AFM) studies. It is anticipated that this study can provide an exact and excellent monomeric unit for controllable and precise supramolecular polymerization. The results achieved here also demonstrate the utility and feasibility of multiple hydrogen bonds to direct the self-assembly of small-molecule building blocks in aqueous media, which provides a strategy for the construction of well-defined and stable supramolecular architectures with chemical functionalities and physical properties as advanced materials for biological applications.
Herein we report a new general method for one-step synthesis of four kinds of fluoroiodane(Ⅲ) reagents by treating the corresponding aryl iodides with silver difluoride (AgF2). This is the first method applicable for the synthesis of all four fluoroiodane(Ⅲ) reagents including p-iodotoluene difluoride (1), fluoro-benziodoxole (2), fluoro-benziodoxolone (3), and fluoro-N-acetylbenziodazole (4). AgF2 was firstly employed in the direct oxidative fluorination of iodobenzene and thus has shown its outstanding oxidation and fluorine-transfer ability. The use of AgF2 has improved the synthesis of fluoroiodane(Ⅲ) reagents by shortening the reaction steps, avoiding the use of hazardous reagents, and simplifying the experimental operations. It was worth noting that we have developed the first one-step direct synthetic method for 3, while 3 can only be synthesized through Cl→F ligand exchange reaction previously.
Traditional synthesis of sulfonylureas largely depends on nucleophilic addition of arylsulfonamides to pre-synthesized isocyanates. Now we report a new access to alkylsulfonylureas with good yields and broad substrate scope. With the insertion of commercialized chlorosulfonyl isocyanate under photoredox catalysis, alkylsulfonylureas are synthesized in one-pot from the corresponding anilines and silyl enolates. A reaction mechanism is proposed showing the transformation undergoes a radical process, and the practicality of this methodology is proven via application to bioactive molecules. Additionally, the anti-cancer and anti-virus screening of these compounds is evaluated.
Wastewater treatment and reclamation from wastewater are essential for the sustainable use of water resource. Zeolite-based heterogeneous catalysis shows great potential in circumventing the current limitations on pollutant removal and transformation to useful chemicals, inspiring advancements towards practical water treatment. This paper summarizes the methods for synthesizing zeolite-based catalyst, and the corresponding advantages and disadvantages. In comparison with traditional Fenton-like reaction, the superiority of zeolite-based catalysis lies in less sludge, wide pH range and easy recyclability. Accordingly, applications of zeolite-based Fenton-like catalysis (ZFCs) in pollutant removal and reclamation of wastewater were reviewed. Emphasis was placed on the methodological strategies in improving ZFCs, including the combination of external driving force (e.g., photocatalysis or electrochemistry), as well as the introduction of various transition metals into zeolite-based catalyst. Possible challenges and future perspectives for ZFCs were proposed.
Recent advances in epoxy resins have been forward to achieving high mechanical performance, thermal stability, and flame retardancy. However, seeking sustainable bio-based epoxy precursors and avoiding introduction of additional flame-retardant agents are still of increasing demand. Here we report the synthesis of p-hydroxycinnamic acid-derived epoxy monomer (HCA-EP) via a simple one-step reaction, and the HCA-EP can be cured with 4, 4′-diaminodiphenylmethane (DDM) to prepare epoxy resins. Compared with the typical petroleum-based epoxy resin, bisphenol A epoxy resin, the HCA-EP-DDM shows a relatively high glass transition temperature (192.9 ℃) and impressive mechanical properties (tensile strength of 98.3 MPa and flexural strength of 158.9 MPa). Furthermore, the HCA-EP-DDM passes the V-1 flammability rating in UL-94 test and presents the limiting oxygen index of 32.6%. Notably, its char yield is as high as 31.6% under N2, and the peak heat rate release is 60% lower than that of bisphenol A epoxy resin. Such findings provide a simple way of using p-hydroxycinnamic acid instead of bisphenol A to construct high-performance bio-based thermosets.
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