查看更多>>摘要：Metal-and oxidant-free photocatalytic C-H alkylation of coumarins is developed in the presence of triphenylphosphine and sodium iodide under blue LEDs irradiation by using the easily available alkyl N-hydroxyphthalimide esters as the alkylation reagents. The metal-and oxidant-free decarboxylative C-H coupling protocol provides various 3-alkylated coumarins, as well as quinoxalinones, in satisfactory yields with excellent C-3 regioselectivity.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Theoretical screenings of D4-molecular cylinders for high-g chiroptical molecules were performed to find one four-panel cycloarylene with an anomalously high theoretical |gabs,calc| value of 1.97. Optical resolutions of enantiomers after developments of elaborate syntheses allowed for spectral analyses of the chiral D4-cylinder. Unexpectedly, the experimental |gabs| value was three orders of magnitude less than the theoretical prediction, and crystallographic analyses combined with theoretical investigations showed radial deformations as one of the possible factors that could considerably affect the |g| value. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Incorporating various heteroaryl motifs into small-molecule moieties of DNA-encoded libraries is beneficial to support hit identification. More privileged heterocycles based libraries are urgently needed to expand the chemical space of the DNA encoded library. Because currently published on-DNA C-N cross-coupling methods mainly focused on exocyclic aromatic amines, lacking systematic investigation for incorporating pharmaceutically valuable N-aryl hetero-aromatic moiety into DNA-encoded libraries, in this paper, we have reported an on-DNA protocol to attach the DNA-linked electrophiles to the (H)N- heteroaryl rings. This method could translate the monofunctional heteroaryl agents into "bifunctional building blocks ", which have been applied for the DNA encoded focused indazole library synthesis. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Macrocyclization proves a useful strategy for obtaining artificial supramolecular hosts via reducing the degrees of freedom of the corresponding precursors. However, synthesis of receptor containing multiple macrocycles is challenging. In this contribution, we describe the rational design and synthesis of a new class of organometallic trimacrocyclic hexasubstituted benzenes 1 and 2 via either metal-ligand coordination or dynamic covalent chemistry strategies. Such class of constructs feature a benzene core fused by three identical metallomacrocycles with high symmetry and interesting physiochemical property, as inferred from the NMR, mass spectrometry, cyclic voltammetry and DFT calculations. Trimacrocycle 2 bearing one ferrocene unit in each sub-macrocycle was found able to selectively capture bromide and iodide, as evidenced by NMR spectroscopy, DFT calculations, as well as molecular dynamics simulations. Thus, we hope this study will somewhat accelerate the development of complex functional host-guest systems for species of interest. (c) 2022 Elsevier Ltd. All rights reserved.
Gourlaouen, ChristopheMislin, Gaetan L. A.Faucon, Aline L.Hoegy, Francoise...
4页
查看更多>>摘要：We show that dipyridylamine-acetamide (Dpaa), can be cleaved under mild acidic conditions (30% formic acid in dichloromethane). The release of the amine function is orthogonal to other acid-labile protecting groups. Calculations suggest that the ease of Dpaa cleavage relies on activation of the carbonyl function by the protonated dipyridylamine nitrogen and activation of a water molecule by a hydrogen-bond network. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Biological carbon fixation can convert carbon dioxide (CO2) into chemicals with a variety of uses, and has thus attracted considerable attention, as CO2 is nonhazardous, inflammable and plentiful in the environment. We report here that alumina (Al2O3) can by itself catalyze the carbonylation of o-phenylenediamines with CO2 to produce 2-benzimidazolones. Such alumina-catalyzed carbonylation with CO2 is applicable to various diamine derivatives to provide the corresponding cyclic ureas. Following the reaction, the alumina catalyst is also advantageous in that it can be filtered, accumulated, and reused. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：This report describes a rapid, efficient, and environment-friendly methodology for electrophilic thiocyanation of activated arenes using sulfated polyborate as a Bronsted acid catalyst and H2O2 as a green oxidizer at 30 ?. The methodology was applied for activated arenes, including indoles and beta-ketoesters, along with recyclability of aqueous quench was demonstrated for four cycles with no loss of catalytic activity. The key benefits of the method are a shorter reaction time, higher yields, and easy work-up under mild reaction condition. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We have developed a novel method to synthesize alpha-diazoesters from alpha-hydrazonoesters with a catalytic amount of Cu(OAc)(2) in acetonitrile. When the reaction was carried out under an argon atmosphere, the reaction stopped halfway, suggesting that this reaction required oxygen to reoxidize the catalyst. Since hydrazonoesters can be obtained by reduction of alpha-diazoesters with P(n-Bu)(3) in diisopropyl ether, these 2 compounds are mutually interconvertible with ease. Whereas alpha-diazoesters are unstable and unsuitable for storage, hydrazonoesters are more stable, especially crystalline hydrazonoesters. Thus, hydrazonoesters, which are suitable for long-term storage, could be conveniently used as precursors for alpha- diazoesters. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：H-phosphonates, H-phosphinates and secondary phosphine oxides are versatile reagents for the construction of complex phosphoryl compounds. Their decade advances in three-component reactions were recorded in this article. Reactions with bicyclo[1.1.1]pentane, alkenes, alkynes, aldehydes, imines, S, Se, et al will be discussed. In this review, we systematically summarized the applications of these P(O)-H compounds in organic synthetic chemistry, and their mechanisms were also discussed.(c) 2022 Published by Elsevier Ltd.
查看更多>>摘要：Ogipeptins A-D are cyclic lipopeptides that were isolated from culture broth by Daiichi Sankyo. Each of them showed antimicrobial activity against Gram-negative bacteria. Ogipeptins are composed of seven amino acid residues, and three of them are rare and unique beta-hydroxy-alpha,gamma-diaminobutyric acids (beta-OH Dabs). The advanced Marfey's method was applied to determine the absolute configuration of beta-OH Dab in ogipeptin A. Herein, we describe the determination method used to confirm the 2:1 ratio of (2S,3S) to (2S,3R) beta-OH Dab isomers in ogipeptins. (C) 2022 Elsevier Ltd. All rights reserved.
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