Han, MeiShen, Mei -HuaZhu, Chi -FanXu, Hua -Dong...
4页
查看更多>>摘要：A series of gamma-lactams were synthesized by intramolecular aza-claisen rearrangement of ketenes using Meldrum's acid as ketene precursor. Derivatives of Meldrum's acid with tertiary ammonia structure were used as raw material, and the reaction was catalyzed by Lewis acid at high-temperature conditions under microwave. Ketene formation by losing acetone and CO2, cyclization and claisen rearrangement occurred in sequence to form the gamma-lactams. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We present a visible light-activated ruthenium-catalysed direct arylation of aryl C-H bonds with aryl (pseudo)halides, which operates at ambient temperature with broad substrate scopes and excellent compatibility of functionalities. The key to success of this strategy is the efficient generation of active catalytic species via photo-induced ligand dissociation. The choices of the bases and solvents also have significant influence on the catalytic efficiency. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：This article reports the regioselective and chemoselective synthesis of 4,5-dialkoxy-2-nitroanilines substituted with two alkoxys at C-4 and C-5. Here we show the optimization protocol of the transetherification reaction used to synthesize 20 new compounds with good to excellent yields (50-92%). We describe a simple and efficient one-step procedure that can be applied to obtain a significant number of pharmacologically active compounds, including antimalarial drug Primaquine analogs. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Fernandez-Canelas, PaulaBarrio, PabloGonzalez, Jose M.
17页
查看更多>>摘要：Haloalkynes can enter a wide variety of metal-catalyzed transformation giving rise to the formation of products with or without showing halide-shift. This article offers an overall view of the reactivity of these substrates under gold catalysis. Particular attention is devoted to intramolecular reactions that involve a concomitant halide-shift process for the case of alkynyl iodides as starting materials.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Hribernik, NivesChiodo, FabrizioPieters, Roland J.Bernardi, Anna...
5页
查看更多>>摘要：Recruitment of natural antibodies towards tumour cells for their elimination by the immune system could be a highly specific and efficacious therapeutic strategy. While natural L-rhamnose has already been explored as a suitable antigen for antibody recruitment, we here report the first rhamnose-based glycomimetic to be used for such purpose. The glycomimetic is designed to be more hydrolytically and enzymatically stable than natural rhamnosides, provides a site for easy further conjugation and proved to capture anti-rhamnose IgG antibodies in serological ELISA assay.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
查看更多>>摘要：An efficient and robust Rh(III)-catalyzed three-component C-H esterification reaction of indole derivatives with vinylene carbonate to access indolyl acetates has been developed.This protocol exhibits high efficiency, good yields, and excellent functional group tolerance. Significantly, this method provides a powerful approach for the late-stage modification of indole-based substrates and natural alcohols.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A new, green, convenient, cost- and atom effective route leading to 3-arylmethyl 4-hydroxyquinolin-2 (1H)-ones from arylaldehydes and 1,3-dicarbonyl compounds in triethyl ammonium formate in good to excellent yield is presented. The provided method foresees the Knoevenagel condensation between a 4-hydroxyquinolin-2(1H)-one and an aromatic aldehyde followed by in situ trapping of the arylidene intermediate with the hydride ion. All synthesized compounds were tested for their antiradical activity against DPPH and GO free radicals. The antiradical activity of the 3-arylmethyl 4-hydroxyquinolin-2 (1H)-ones was comparable to or even higher than that of some commercially widely used antioxidants like BHT, TBHQ, or a-tocopherol. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Two new pincer-type bisnitroxides have been synthesized, where tetramethylenedioxy and o-xylylenedioxy are chosen as a bridge between the p-position of two tert-butyl phenyl nitroxide moieties. The X-ray crystal structure analysis clarified the linear and U-shaped molecular structures for the former and latter compounds, respectively. In the toluene solution ESR of the tetramethylenedioxy derivative, five hyperfine splitting lines were recorded, but a center signal was somewhat lowered. The ESR spectra of the o-xylylenedioxy derivative displayed a typical 1/2/3/2/1 five-line pattern at 370 K, and an "alternating line-width " effect appeared in 210-230 K. These spectra were reproduced by simulation, based on the proposed model where a few conformers have differing exchange couplings. The contribution showing strong exchange is reasonably ascribable to the U-shaped conformer. Thus, the solid and solution experimental results are compatible with each other.
查看更多>>摘要：A highly stereoselective asymmetric Henry reaction using a double fluorous-tagged Co-salen complex was conducted. The introduction of two fluorous tags into the Co-salen complex was found to be more effective in terms of improving stereoselectivity than the introduction of a strong electron-withdrawing nitro group into the same position of the salen ligand. The observed stereoselectivity was significantly higher than that when using a Jacobsen-type Co-salen complex bearing the same asymmetric source. (c) 2022 Elsevier Ltd. All rights reserved.
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