carboxamides are valuable in pharmaceutical applications, the preparation N-(indol-2-yl)amides with similar structures continues to be challenging. Herein we report on visible-light-induced late-stage photoredox C–H amidation with N-unprotected indoles and tryptophan-containing peptides, leading to the formation of N-(indol-2-yl)amide derivatives. N-Unprotected indoles and aryloxyamides that contain an electron-withdrawing
distorted amides having both high degree of nitrogen pyramidalization (38–55°) and amide twist (12–30°). In solution they exist in a defined conformation that is evidenced by the presence of a sharp signal of N-methyl protons at low temperature. They do not isomerize in solutions. Some of them slowly undergo the N-O bond scission above 100 °C. Both isomers are not as sensitive to neutral hydrolysis as twisted
使用二硫烷(方法 A)或二苯基硫代膦酰氯(方法 B)对 N-甲基对取代苯异羟肟酸进行硫代膦酰化,仅提供相应 O-硫代磷酰衍生物的一种构象异构体(X 射线和 NMR 分析)。进行 P-转酰胺氧基化反应是硫代膦酰化可逆性的证据。只有那些在芳酰基残基中含有强 EWG 取代基或在磷原子上含有大取代基的产物才具有 E 构象。DFT 计算证实了每个异构体的能量支配。Z-异构体是扭曲的酰胺,具有高度的氮锥化(38-55°)和酰胺扭曲(12-30°)。在溶液中,它们以确定的构象存在,低温下 N-甲基质子的尖锐信号的存在证明了这一点。它们在溶液中不会异构化。其中一些在 100 °C 以上缓慢发生 NO 键断裂。两种异构体对中性水解均不像扭曲酰胺那样敏感,并且对胺呈惰性。碱性水解的速率可以与异羟肟酸的 pKa 相关联。由于它们出色的亲氧性,这些化合物可以被定义为神经毒剂替代品和氟化磷的更安全替代品,用于丝氨酸活性酶抑制研究。
n-Bu4NI/H2O2-catalyzed mild conversion of hydroxamic acids to carboxylic acids
A variety of aromatic and aliphatic hydroxamic acids were transformed into carboxylic acids employing tetra-n-butylammonium iodide and hydrogen peroxide. The reaction was executed across a range of substrates encompassing diverse functional groups, delivering good to excellent yields. This catalytic hydrolysis features gentle reaction conditions and the application of a non-hazardous, cleanly processed
N-substituted arylhydroxamic acids as acetylcholinesterase reactivators
作者:Denys Bondar、Illia V. Kapitanov、Lenka Pulkrabkova、Ondřej Soukup、Daniel Jun、Fernanda D. Botelho、Tanos C.C. França、Kamil Kuča、Yevgen Karpichev
DOI:10.1016/j.cbi.2022.110078
日期:2022.9
N-butyl derivatives have better balanced combination of properties; among them, N-butylsalicylhydroxamic acid is most promising. The studied compounds demonstrate modest reactivation capacity; change of N–H by N–Me ensures the reactivation capacity in studied concentrations on all studied OP substrates; among N-butyl derivatives, the N-butylsalicylhydroxamic acid demonstrates most promising results within