Interception of amide ylides with sulfonamides: synthesis of (<i>E</i>)-<i>N</i>-sulfonyl amidines catalyzed by Zn(OTf)<sub>2</sub>
作者:Jijun Chen、Wenhao Long、Shangwen Fang、Yonggang Yang、Xiaobing Wan
DOI:10.1039/c7cc07364j
日期:——
Through the interception of amide ylides with sulfonamides, we herein report the first general example of an intermolecular condensation reaction between sulfonamides and amides. Beyond formamides, this approach was successfully applied to a variety of lactams and linear amides, giving rise to a broad array of (E)-N-sulfonyl amidines.
Demethylative Alkylation of Methionine Residue by Employing the Sulfonium as the Key Intermediate
作者:Qi-Long Hu、Jia-Tian Liu、Jian Li、Yang Ge、Zhendong Song、Albert S. C. Chan、Xiao-Feng Xiong
DOI:10.1021/acs.orglett.1c03241
日期:2021.11.5
Methionine (Met) offers a valuable handle to achieve peptide chemical modification owing to its unique thioether functional group. In contrast with cysteine, the site-selective functionalization of the hydrophobic and redox-sensitive thioether motif on peptides is still challenging, and strategies for diversification on the Met residue are rarely disclosed. Herein we report a transition-metal-free
由于其独特的硫醚官能团,蛋氨酸 (Met) 为实现肽化学修饰提供了一种有价值的方法。与半胱氨酸相比,肽上疏水和氧化还原敏感的硫醚基序的位点选择性功能化仍然具有挑战性,并且很少公开 Met 残基多样化的策略。在这里,我们报告了一种无过渡金属和氧化还原中性方法,用于具有底物多样性的 Met 多样化,可用于合成环肽。
Preparation of Diglycolamides via Schotten–Baumann Approach and Direct Amidation of Esters
Diglycolyl chlorides, commercially available or obtained from the corresponding dicarboxylic acids, have been converted into the corresponding diamides by reaction with a wide range of amines in an organic-aqueous biphasic system (Schotten–Baumann approach) in high yields. Treatment with poly(4-styrenesulfonic acid) afforded the pure compounds. Substituted diglycolyl diesters, obtained by coupling
Structural Elucidation of Z- and E- Isomers of 5-Alkyl-4-ethoxycarbonyl-5-(4`-chlorophenyl)-3-oxa-4-pentenoic Acids
作者:H. Madkour
DOI:10.3390/50500737
日期:——
in the presence of sodium hydride as a basic catalyst. The Z-isomers of 2a and 2b were found to be predominant. The behaviour of the corresponding anhydrides towards the action of hydrazine, phenylhydrazine, primary aromatic amines, hydrocarbons and ethanolysis has also been investigated. The structures and configurations of the products have been elucidated by chemical and spectroscopic means.
Hydroxy ether carboxylates represented by the formula ##EQU1## wherein M is alkali metal, ammonium, alkyl ammonium or alkanol ammonium and A is hydrogen, methyl, ethyl, or CH.sub.2 OH, are useful as complexing agents and detergency builders. The ester and acid forms of such compounds are useful as intermediates for preparation of the salts.