Copper(II)-Catalyzed Aerobic Oxidative Synthesis of Substituted 1,2,3- and 1,2,4-Triazoles from Bisarylhydrazones via C–H Functionalization/C–C/N–N/C–N Bonds Formation
摘要:
An unprecedented copper(II)-catalyzed aerobic oxidative synthesis of 2,4,5-triary1-1,2,3-triazoles and 1,3,5-triaryl-1,2,4-triazoles from bisarylhydrazones as the common starting precursor has been achieved via cascade C-H functionalization/C-C/N-N/C-N bonds formation under mild reaction conditions. One of the enthralling outcomes of this strategy is the copper(II)-catalyzed room temperature C-H functionalization/C-N bond formation in presence of air, which has been accomplished during the synthesis of substituted 1,2,4-triazoles. This new class of compounds could give prospective luminescence as an iconic component in the area of pharmaceutical and biological sciences. The intermediates for both the processes have been isolated to elucidate the mechanistic scenario.
A Brønsted acid-mediated synthesis of pyrazoles from conjugated hydrazones through a β-protonation/nucleophilic addition/cyclization/aromatization sequence was developed. This protocol utilizing the ambiphilic reactivity of hydrazones enables not only self-condensation but also cross-condensation, affording multisubstituted pyrazoles in high yields, with a broad substrate scope. This sequential reaction
Regioselective Synthesis of 4-Nitro- or 4-Chloro-Tetrasubstituted Pyrazoles from Hydrazones and β-Halo-β-nitrostyrenes
作者:Xiaohu Deng、Jimmy T. Liang、Neelakandha S. Mani
DOI:10.1002/ejoc.201301294
日期:2014.1
We report an acid-catalyzed cycloaddition reaction of hydrazones with β-bromo- or β-chloro-β-nitrostyrenes for the regioselectivesynthesis of 4-nitro- or 4-chloro-tetrasubstitutedpyrazoles. Arising from a common 4-halo-4-nitropyrazolidine intermediate, the identity of the pyrazole product formed is dependent on the relative leaving group abilities of the halo and nitro substituents.
Broad‐Spectrum Antifungal Agents: Fluorinated Aryl‐ and Heteroaryl‐Substituted Hydrazones
作者:Nishad Thamban Chandrika、Emily K. Dennis、Katelyn R. Brubaker、Stefan Kwiatkowski、David S. Watt、Sylvie Garneau‐Tsodikova
DOI:10.1002/cmdc.202000626
日期:2021.1.8
Fluorinated aryl‐ and heteroaryl‐substituted monohydrazones displayed excellent broad‐spectrum activity against various fungal strains, including a panel of clinically relevant Candida auris strains relative to a control antifungal agent, voriconazole (VRC). These monohydrazones displayed less hemolysis of murine red blood cells than that of VRC at the same concentrations, possessed fungicidal activity
氟化芳基和杂芳基取代的单腙对各种真菌菌株表现出优异的广谱活性,包括相对于对照抗真菌剂伏立康唑 (VRC) 的一组临床相关耳念珠菌菌株。在相同浓度下,这些一腙对小鼠红细胞的溶血作用比 VRC 少,在时间杀灭研究中具有杀菌活性,并且没有表现出哺乳动物细胞的细胞毒性。此外,这些一腙可以防止生物膜的形成,否则会阻碍抗生素的有效性,并且当暴露于耳念珠菌AR Bank # 0390 15 代以上时,不会引发耐药性的发展。
Halogenated Diazabutadiene Dyes: Synthesis, Structures, Supramolecular Features, and Theoretical Studies
作者:Valentine G. Nenajdenko、Namiq G. Shikhaliyev、Abel M. Maharramov、Khanim N. Bagirova、Gulnar T. Suleymanova、Alexander S. Novikov、Victor N. Khrustalev、Alexander G. Tskhovrebov
DOI:10.3390/molecules25215013
日期:——
Novel halogenated aromatic dichlorodiazadienes were prepared via copper-mediated oxidative coupling between the corresponding hydrazones and CCl4. These rare azo-dyes were characterized using 1H and 13C NMR techniques and X-ray diffraction analysis for five halogenated dichlorodiazadienes. Multiple non-covalent halogen···halogen interactions were detected in the solid state and studied by DFT calculations
Base-Mediated Reaction of Hydrazones and Nitroolefins with a Reversed Regioselectivity: A Novel Synthesis of 1,3,4-Trisubstituted Pyrazoles
作者:Xiaohu Deng、Neelakandha S. Mani
DOI:10.1021/ol800200j
日期:2008.3.1
A regioselectivesynthesis of 1,3,4-tri- or 1,3,4,5-tetrasubstituted pyrazoles by the reaction of hydrazones with nitroolefins is described. Mediated with strong bases such as t-BuOK, the reaction exhibits a reversed, exclusive 1,3,4-regioselectivity. Subsequent quenching with strong acids such as TFA is essential to achieve good yields. A plausible stepwise cycloaddition reaction mechanism is proposed