Nitrosation of 1-phenyl-3-(pyridylmethyl)ureas and the reactivity of two nitrosated isomers.
摘要:
1-苯基-3-(吡啶甲基)脲(I)在酸性条件下与亚硝酸钠进行亚硝化反应,生成了两个位置异构体,1-亚硝基-1-苯基-3-(吡啶甲基)脲(II)和3-亚硝基-1-苯基-3-(吡啶甲基)脲(III)。亚硝化反应使用了几种亚硝化试剂在不同条件下进行,每个异构体的鉴定采用高效液相色谱法。区域选择性依赖于所用的介质和试剂。在0°C下,使用气体亚硝化试剂在有机溶剂中,I主要生成III。亚硝酸钠与酸(1 M 高氯酸、1 M 盐酸或99% 甲酸)的组合主要生成II。然而,使用N2O3时,主要产物取决于介质的pH值。此外,还考察了亚硝基异构体的化学性质和抗肿瘤活性的差异。
Esterification of Tertiary Amides by Alcohols Through C−N Bond Cleavage over CeO
<sub>2</sub>
作者:Takashi Toyao、Md. Nurnobi Rashed、Yoshitsugu Morita、Takashi Kamachi、S. M. A. Hakim Siddiki、Md. A. Ali、A. S. Touchy、Kenichi Kon、Zen Maeno、Kazunari Yoshizawa、Ken‐ichi Shimizu
DOI:10.1002/cctc.201801098
日期:2019.1.9
process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0 kcal/mol. This value matches well with experimental value (17.9 kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by in situ FT‐IR and temperatureprogrammeddesorption using probe molecules demonstrate that both acidic and
Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
作者:Changyu Huang、Jinpeng Li、Jiaquan Wang、Qingshu Zheng、Zhenhua Li、Tao Tu
DOI:10.1007/s11426-020-9883-3
日期:2021.1
interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments
Imidazolium salts have been effectively employed as suitable acyl transfer agents in amidation and esterification in organic synthesis. The weak acyl C(O)–C imidazolium bond was exploited to generate acyl electrophiles, which further react with amines and alcohols to afford amides and esters. The broad substrate scope of anilines and benzylic amines and base-promoted conditions are the benefits of
Base-catalyzed retro-Claisen condensation: a convenient esterification of alcohols via C–C bond cleavage of ketones to afford acylating sources
作者:Feng Xie、Fengxia Yan、Mengmeng Chen、Min Zhang
DOI:10.1039/c4ra04618h
日期:——
The base-catalyzed esterification of alcohols via retro-Claisen condensation has been demonstrated for the first time. A variety of alcohols including aryl- and heteroaryl methanols as well as aliphatic ones underwent efficient acylation to give the ester products in reasonable to good yields upon isolation. Not only conventional 1,3-diketones but also strong electron-withdrawing group containing acetophenones
Visible‐Light‐Enabled Trifluoromethylative Pyridylation of Alkenes from Pyridines and Triflic Anhydride
作者:Kangjae Lee、Seojin Lee、Namhoon Kim、Seonyul Kim、Sungwoo Hong
DOI:10.1002/anie.202004439
日期:2020.8.3
strategy for visible‐light‐enabled site‐selective trifluoromethylative pyridylation of unactivated alkenes has been developed using pyridines and triflic anhydride (Tf2O). Intriguingly, the N‐triflylpyridinium salts, generated in situ from pyridines and Tf2O, serve as effective modular bifunctionalreagents to install both CF3 and pyridyl groups to various olefins while controlling C4‐selectivity in radical