通过非手性α-氨基异丁酸(Aib),ArSO 2-(Aib)5 -OMe(Ar =对甲苯基,对溴苯基和对甲氧基苯基)的同五肽的分子构象,堆积结构和分子间相互作用单晶X射线衍射分析。将肽折叠成3个10螺旋构象,该构象由两个或三个连续的III型或III'型十原子分子内氢键合的β-转角组成。在打包模式下,左手(M)和右手(P)3 10-螺旋分子形成具有头尾型分子间氢键的线性网络结构。根据功能基团或取代基的不同,获得了两种由同手性序列(⋯ M ⋯ M ⋯ M ⋯或⋯ P ⋯ P ⋯ P ⋯)和杂手性序列(⋯ M ⋯ P ⋯ M ⋯ P consisting)组成的网络结构。肽。有趣的是,当使用不同的结晶介质时,具有对甲苯基的肽1a结晶不同。
Palladium-catalyzed site-selective hydrogen isotope exchange (HIE) reaction of arylsulfonamides using amino acid auxiliary
作者:Wei Liu、Xingyu Xu、Hongyan Zhao、Xiaoyu Yan
DOI:10.1016/j.tet.2018.06.024
日期:2018.7
Hydrogenisotopeexchange (HIE) is a versatile method for the introduction of deuterium to organic compounds. Herein, regioselective deuteration of sulfonamides is achieved by palladium-Catalyzed HIE reaction. By using amino acid as weakly coordination-directing auxiliary, a variety of sulfonamides are efficiently deuterated at the ortho-position. Placing competing directing groups on the aromatic
α-Amino Acid Sulfonamides as Versatile Sulfonylation Reagents: Silver-Catalyzed Synthesis of Coumarins and Oxindoles by Radical Cyclization
作者:Kyalo Stephen Kanyiva、Daisuke Hamada、Sohei Makino、Hideaki Takano、Takanori Shibata
DOI:10.1002/ejoc.201800901
日期:2018.11.25
silver‐catalyzed sulfonylation strategy using sulfonamides derived from α‐amino acids is described. The reaction proceeded via decarboxylation, N–S bond cleavage and radical cyclization to provide a variety of coumarins. The reaction was suitable for the synthesis of 2‐oxindoles and an isoquinolinedione by the capturing of the sulfonyl radical with an alkene moiety and cyclization.
sulfonamide derivatives via palladium(II)‐catalyzed CH bond activation by employing an amino acid moiety as the bidentate directing group has been developed. The protocol proceeded efficiently in water; high yields and broad substrate scope were achieved. The reaction shows good functional group compatibility and proceeds in a highly selective manner at the ortho position of arenes connected to sulfonamide
Palladium(II)/copper(I)-catalyzed sequential CH arylation and oxidative CN bond cleavage of aryl sulfonamino acids: Efficient one-pot synthesis of primary biaryl sulfonamides
作者:Wei Liu、Yongli Zhao、Fei Yi、Junmin Chen
DOI:10.1016/j.tet.2016.10.056
日期:2016.12
A versatile strategy for the one-pot synthesis of primary biaryl-based sulfonamides has been developed via a tandem process consisting of palladium-catalyzed CH arylation and subsequent copper-catalyzed oxidative CN bondcleavage of aryl sulfonamino acids. Both electron-withdrawing and electron-donating functionalities can be introduced into the ortho positions of arenes bearing a variety of substituents
The uncommon amino-acid 2-methylalanine (α-aminoisobutyric acid, Aib) was investigated by 13C-NMR. The chemical shifts of amino- or carboxy-protected derivatives of Aib and of protected oligopeptides are discussed with respect to neighbouring groups and amino acids. The pH-dependence of the 13C-NMR spectra of Aib, Aib-Ala, Ala-Aib, Aib-Ala-Aib and Aib-Ala-Aib-Ala-Aib was studied. Using these examples