Search results for "Structural isomer"
showing 7 items of 57 documents
ChemInform Abstract: Gold(I)-Catalyzed Intermolecular Oxyarylation of Alkynes: Unexpected Regiochemistry in the Alkylation of Arenes.
2010
The reaction between acetylenes and sulfoxides, studied as a test case for gold-catalyzed intermolecular addition, provides the oxyarylation compounds 3 in good yields. Unpredictably, in all cases a single regioisomer arising from the electrophilic aromatic alkylation at the position adjacent to the sulfur atom is obtained instead of the expected Friedel−Crafts regioisomer. A new concerted mechanism based on DFT calculations is proposed to account for the products in this intermolecular gold(I)-catalyzed reaction.
Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence.
2017
A study exploring the chemical behavior of some dihydroxylated β-amino ester stereo- and regioisomers, derived from unsaturated cyclic β-amino acids is described. The nucleophilic fluorinations involving hydroxy–fluorine exchange of some highly functionalized alicyclic diol derivatives have been carried out in view of selective fluorination, investigating substrate dependence, neighboring group assistance and chemodifferentiation.
Angular Regioselectivity in the Reactions of 2-Thioxopyrimidin-4-ones and Hydrazonoyl Chlorides : Synthesis of Novel Stereoisomeric Octahydro[1,2,4]t…
2020
The regioselective synthesis of cis and trans stereoisomers of variously functionalized octahydro[1,2,4]triazolo[4,3-a]quinazolin-5-ones was performed. The 2-thioxopyrimidin-4-ones used in the synthesis reacted with hydrazonoyl chlorides in a regioselective manner to produce the angular regioisomers [1,2,4]triazolo[4,3-a]quinazolin-5-ones rather than the linear isomers [1,2,4]triazolo[4,3-a]quinazolin-5-ones. The synthesis process took place with electronic control. The angular regiochemistry of the products was confirmed by X-ray experiments and two-dimensional NMR studies.
Dicyclopentaannelated Hexa-peri-hexabenzocoronenes with a Singlet Biradical Ground State
2021
Abstract Synthesis of two dicyclopentaannelated hexa‐peri‐hexabenzocoronene (PHBC) regioisomers was carried out, using nonplanar oligoaryl precursors with fluorenyl groups: mPHBC 8 with two pentagons in the “meta”‐configuration was obtained as a stable molecule, while its structural isomer with the “para”‐configuration, pPHBC 16, could be generated and characterized only in situ due to its high chemical reactivity. Both PHBCs exhibit low energy gaps, as reflected by UV‐vis‐NIR absorption and electrochemical measurements. They also show open‐shell singlet ground states according to electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations. The use of…
ChemInform Abstract: Regioisomeric 5(3)-Aminomethyl-3(5)-phenylisoxazoles: Synthesis, Spectroscopic Discrimination, and Muscarinic Activity.
2010
The regioselective synthesis of isomeric 5(3)-aminomethyl-3(5)-phenyl isoxazoles using different methods is described. Spectroscopic data, especially mass spectrometric fragmentation, were used to identify and characterize the regioisomers. The muscarinic activity of these isoxazoles was assayed on isolated guinea-pig ileum and atria as well as on isolated rabbit vas deferens. Regioisomere 5(3)-Aminomethyl-3(5)-phenyl-isoxazole: Synthese, spektroskopische Unterscheidung und muskarinische Aktivitat Es werden verschiedene Verfahren zur regioselektiven Darstellung von 5(3)-Aminomethyl-3(5)-phenyl-isoxazolen beschrieben, die anhand ihrer spektroskopischen Daten, insbesondere der massenspektrosk…
Hexagonal Microparticles from Hierarchical Self-Organization of Chiral Trigonal Pd3L6 Macrotetracycles
2021
Construction of structurally complex architectures using inherently chiral, asymmetric, or multi-heterotopic ligands is a major challenge in metallosupramolecular chemistry. Moreover, the hierarchical self-organization of such complexes is unique. Here, we introduce a water-soluble, facially amphiphilic, amphoteric, chiral, asymmetric, and hetero-tritopic ligand derived from natural bile acid, ursodeoxycholic acid. We show that via the supramolecular transmetalation reaction, using nitrates of Cu(II) or Fe(III), and subsequently Pd(II), a superchiral Pd3L6 complex can be obtained. Even though several possible constitutional isomers of Pd3L6 could be formed, because of the ligand asymmetry a…
Experimental and Theoretical Investigations of Structural Isomers of Dichalcogenoimidodiphosphinate Dimers: Dichalcogenides or Spirocyclic Contact Io…
2007
A synthetic protocol for the tert-butyl-substituted dichalcogenoimidodiphosphinates [Na(tmeda){(EPtBu2)2N}] (3 a, E=S; 3 b, E=Se; 3 c, E=Te) has been developed. The one-electron oxidation of the sodium complexes [Na(tmeda){(EPR2)2N}] with iodine produces a series of neutral dimers (EPR2NPR2E[BOND])2 (4 b, E=Se, R=iPr; 4 c, E=Te, R=iPr; 5 a, E=S, R=tBu; 5 b, E=Se, R=tBu; 5 c, E=Te, R=tBu). Attempts to prepare 4 a (E=S, R=iPr) in a similar manner produced a mixture including HN(SPiPr2). Compounds 4 b, 4 c and 5 a–c were characterised by multinuclear NMR spectra and by X-ray crystallography, which revealed two alternative structures for these dimeric molecules. The derivatives 4 b, 4 c, 5 a an…