report a strategy for per-residue programming of two dihedral angles of β-peptoids, which is useful for restricting conformational space of the oligomers. The oligomer was found to form a unique loop conformation that is stabilized by the backbone rotational restrictions. Circular dichroism and NMR spectroscopic analyses and X-ray crystallographic analysis of the oligomer are presented. The strategy would
天然和合成低聚物的独特折叠结构是其独特功能的最基本基础。N-取代的 β-肽或 β-类肽是合成低聚物,具有折叠成不同三维结构的巨大潜力,因为单体中存在四个可旋转的键,并且具有高度模块化的合成可访问性。然而,四个可旋转键的存在对β-拟肽的构象控制提出了挑战。在这里,我们报告了 β-peptoids 的两个二面角的每个残基编程的策略,这对于限制寡聚体的构象空间很有用。发现低聚物形成独特的环构象,该构象通过骨架旋转限制而稳定。给出了低聚物的圆二色性和 NMR 光谱分析和 X 射线晶体学分析。该策略将显着促进发现许多更独特的 β-拟肽折叠结构。
Solid-Phase Synthesis of Trisubstituted 2,5-Dihydrobenzo[<i>f</i>][1,2,5]thiadiazepine 1,1-Dioxide Derivatives
作者:Veronika Fülöpová、Viktor Krchňák
DOI:10.1021/co500084k
日期:2014.8.11
The solid-phase synthesis of trisubstituted 2,5-dihydrobenzo[f][1,2,5]thiadiazepine 1,1-dioxides is reported. Acyclic polymer-supported intermediates were prepared using commercially available building blocks: Fmoc-protected amino acids, 2-nitrobenzenesulfonyl chlorides, and bromoketones. The acyclic precursors underwent acid-mediated release from the resin and the cyclization was completed in solution.
Solid-Phase Synthesis of 2-Aryl-3-alkylamino-1<i>H</i>-indoles from 2-Nitro-<i>N</i>-(2-oxo-2-arylethyl)benzenesulfonamides via Base-Mediated <i>C</i>-Arylation
作者:Eva Schütznerová、Viktor Krchňák
DOI:10.1021/co500167g
日期:2015.2.9
Polymer-supported 2-nitro-N-(2-oxo-2-arylethyl)benzenesulfonamides, prepared from resin-bound amines by sulfonylation with 2-nitrobenzenesulfonyl chlorides followed by alkylation with alpha-bromoacetophenones, represent advanced intermediates for the synthesis of different nitrogenous heterocycles. We report their application for the synthesis of 2-aryl-3-alkylamino-1H-indoles via base-mediated C-arylation reactions followed by the reduction of the C-arylated intermediates. Linear precursors for C-arylation were prepared on solid-phase support from simple, commercially available building blocks. The effects of different substituents on the amino and aryl groups were addressed.
Remarkably Efficient Synthesis of 2<i>H</i>-Indazole 1-Oxides and 2<i>H</i>-Indazoles via Tandem Carbon−Carbon Followed by Nitrogen−Nitrogen Bond Formation
followed by nitrogen-nitrogen bond formations quantitatively converted N-alkyl-2-nitro-N-(2-oxo-2-aryl-ethyl)-benzenesulfonamides to 2H-indazoles 1-oxides under mild conditions. Triphenylphosphine or mesylchloride/triethylamine-mediated deoxygenation afforded 2H-indazoles.