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21.
Katherine E. Boehle Jake Gilliand Christopher R. Wheeldon Amethyst Holder Jaclyn A. Adkins Dr. Brian J. Geiss Dr. Elizabeth P. Ryan Dr. Charles S. Henry 《Angewandte Chemie (International ed. in English)》2017,56(24):6886-6890
Antimicrobial resistance (AMR), the ability of a bacterial species to resist the action of an antimicrobial drug, has been on the rise due to the widespread use of antimicrobial agents. Per the World Health Organization, AMR has an estimated annual cost of USD 34 billion in the US and is predicted to be the number one cause of death worldwide by 2050. One way AMR bacteria can spread, and by which individuals can contract AMR infections, is through contaminated water. Monitoring AMR bacteria in the environment currently requires that samples be transported to a central laboratory for slow and labor intensive tests. We have developed an inexpensive assay using paper-based analytical devices (PADs) that can test for the presence of β-lactamase-mediated resistance. To demonstrate viability, the PAD was used to detect β-lactam resistance in wastewater and sewage and identified resistance in individual bacterial species isolated from environmental water sources. 相似文献
22.
《Comptes Rendus Chimie》2017,20(2):140-145
An aqueous microwave (mw)-assisted DMAP catalyzed one-pot highly efficient route to synthesize β-phosphonomalonates and 2-amino-4H-chromen-4-yl phosphonates has been demonstrated via the domino Knoevenagel-phospha-Michael reaction of aryl aldehyde/salicylaldehyde, malononitrile/ethyl cyanoacetate and alkyl phosphite ester. Optimization of reaction conditions were performed by using conventional and microwave synthetic approaches. This conversion proceeded smoothly to deliver the desired product in good to excellent yields (75–95%) in a short reaction time (10–12 min). The present methodology is very simple, environmentally benign, high yielding and has very well demonstrated the synergistic effect of water and microwaves. 相似文献
23.
Anna Chandrasekar Murali Prakash Nayak Shashwat Nayak Sabyasachi Das Dr. Satyaprasad P. Senanayak Prof. Krishnan Venkatasubbaiah 《Angewandte Chemie (International ed. in English)》2023,62(11):e202216871
Development of new n-type semiconductors with tunable band gap and dielectric constant has significant implication in dissociating bound charge carrier relevant for demonstrating high performance optoelectronic devices. Boron-β-thioketonates (MTDKB), analogues to boron-β-diketonates containing a sulfur atom in the framework of β-diketones were synthesized. Bulk transport measurement exhibited an outstanding bulk electron mobility of ≈0.003 cm2 V−1 s−1, which is among the best values reported till date in these class of semiconducting materials and correspondingly a single junction photo responsivity of upto 6 mA W−1 was obtained. This new family of O,S-chelated boron compounds exhibited luminescence in the far red/near-infrared region. The remarkable red shift of 89 nm (fluorescence) observed for 4 a in comparison with analogues boron-β-diketonate signifies the importance of sulfur in these molecules. MTDKBs with amine functionality have also been investigated as an ON/OFF fluorescent sensor. 相似文献
24.
Dr. Qiang Wang Prof. Lars Eriksson Prof. Kálmán J. Szabó 《Angewandte Chemie (International ed. in English)》2023,62(19):e202301481
Homologation of trisubstituted fluoroalkenes followed by allylboration of aldehyde, ketone and imine substrates is suitable for synthesis of β-fluorohydrin and amine products. In the presence of (R)-iodo-BINOL catalyst enantioselectivities up to 99 % can be achieved by formation of a single stereoisomer with adjacent stereocenters, of which one is a tertiary C−F center. 相似文献
25.
Liangshen Duan Qin Nie Yongxin Hu Liming Wang Kaiyan Guo Zhuoyi Zhou Xu Song Yuanhong Tu Hui Liu Thomas Hansen Jian-song Sun Qingju Zhang 《Angewandte Chemie (International ed. in English)》2023,62(33):e202306971
Herein, we described the first synthesis of the pentasaccharide and decasaccharide of the A. baumannii ATCC 17961 O-antigen for developing a synthetic carbohydrate-based vaccine against A. baumannii infection. The efficient synthesis of the rare sugar 2,3-diacetamido-glucuronate was achieved using our recently introduced organocatalytic glycosylation method. We found, for the first time, that long-range levulinoyl group participation via a hydrogen bond can result in a significantly improved β-selectivity in glycosylations. This solves the stereoselectivity problem of highly branched galactose acceptors. The proposed mechanism was supported by control experiments and DFT computations. Benefiting from the long-range levulinoyl group participation strategy, the pentasaccharide donor and acceptor were obtained via an efficient [2+1+2] one-pot glycosylation method and were used for the target decasaccharide synthesis. 相似文献
26.
Dongdong Li Prof. Dr. Chaoren Shen Zhiyao Si Prof. Dr. Lu Liu 《Angewandte Chemie (International ed. in English)》2023,62(42):e202310283
An unprecedented Pd-catalyzed fluorinative bifunctionalization of aziridines and azetidines was successfully developed via regioselective C−C and C−F bond cleavage of gem-difluorocyclopropanes, leading to various β,β′-bisfluorinated amines and β,γ-bisfluorinated amines. This reaction was achieved by incorporating a 2-fluorinated allyl group and a fluorine atom scissored from gem-difluorocyclopropane in 100 % atom economy for the first time. The mechanistic investigations indicated that the reaction underwent amine attacking 2-fluorinated allyl palladium complex to generate η2-coordinated N-allyl aziridine followed by fluoride ligand transfer affording the final β- and γ-fluorinated amines. 相似文献
27.
Mingjie Zeng Changyue Yu Yibing Wang Jingjing Wang Jiang Wang Hong Liu 《Angewandte Chemie (International ed. in English)》2023,62(22):e202300424
We report a ligand-controlled CoII-catalyzed C(sp3)−C(sp3) coupling hydroalkylation for direct and β-selective synthesis of 2-deoxy-C-glycosides from glycals. This reaction proceeds by a radical pathway for alkyl halide activation and is β-selective through ligand control. This approach may inspire the development of further stereoselective coupling reactions with potential application in the field of carbohydrates. 相似文献
28.
Vivek W. Bhoyare Akash G. Tathe Prof. Vincent Gandon Dr. Nitin T. Patil 《Angewandte Chemie (International ed. in English)》2023,62(46):e202312786
The successful realization of gold-catalyzed chain-walking reactions, facilitated by ligand-enabled Au(I)/Au(III) redox catalysis, has been reported for the first time. This breakthrough has led to the development of gold-catalyzed annulation reaction of alkenes with iodoarenes by leveraging the interplay of chain-walking and π-activation reactivity mode. The reaction mechanism has been elucidated through comprehensive experimental and computational studies. 相似文献
29.
Dhananjay Yadav Prof. Dr. Maya Shankar Singh 《European journal of organic chemistry》2023,26(10):e202201335
An operationally simple and efficient cascade approach to access a series of 1,3-thiazinanes has been developed through intermolecular [3+3] heteroannulative coupling employing β-ketothioamide as a C1 N1S1 unit and epichlorohydrin as a C3 unit at room temperature for the first time. The reaction proceeds by nucleophilic attack of thiocarbonyl sulfur to less hindered primary carbon of oxirane followed by sequential intramolecular N-cyclization and dehydrochlorination enabling the coupling by cleavage of C−O bond and formation of two new C−S and C−N bonds in one stretch. This protocol not only avoids potential toxicity and tedious work up procedures, but also features open atmosphere, good to high yields, gram-scalability, and easy performance from inexpensive, readily available starting materials under transition-metal-free conditions. A probable mechanism for the formation of 1,3-thiazinanes has been suggested. 相似文献
30.
A Dual Photoredox- and Cp2TiCl2-Catalyzed Approach for the Direct Access to α-Vinyl-β-hydroxy Esters
Emanuele Pinosa Prof. Andrea Gualandi Dr. Andrea Fermi Prof. Paola Ceroni Prof. Pier Giorgio Cozzi Dr. Francesco Calogero 《European journal of organic chemistry》2023,26(38):e202300421
For the first time, a dual photoredox- and titanocene-catalyzed methodology for the regioselective access to α-vinyl-β-hydroxy esters towards aldehyde allylation with 4-bromobut-2-enoate is reported. The protocol is based on the Barbier-type properties of the inexpensive and available Cp2TiCl2 in catalytic amount (5 mol%). The developed mild reaction conditions gave access to a library of differently functionalized α-vinyl-β-hydroxy esters in moderate diastereoselectivity, employing the commercially available ethyl 4-bromobut-2-enoate and both aromatic and aliphatic aldehydes. The reaction was realized under visible light irradiation, in the presence of an organophotocatalyst (3DPAFIPN, 2 mol%) combined with Hantzsch's ester as the sacrificial reductant. In contrast to other Barbier-type reactions employing ethyl 4-bromobut-2-enoate, the photoredox system ensures a better regioselectivity. Moreover, the use of preformed organometallic nucleophilic species (e. g., dienolborinates), and the need of metal reductants or stoichiometric amount of transition metals in low oxidation state for Barbier-type reactions, is avoided. To support the experimental evidence, a detailed photophysical study shed light on the mechanism of the reaction. 相似文献