Trifluoromethylated (tetrahydropyrrolo) quinazolinones by a new three‐component reaction and facile assignment of the regio‐ and stereoisomers formed by NMR spectroscopy

A new three‐component cyclisation reactions of methyl 3,3,3‐trifluoropyruvate, 2‐aminobenzylamine and oxo compounds afforded tetrahydropyrroloquinazolinones of the types 4 and 5 as mixtures of regio‐ and stereoisomers. Whereas standard 1D NMR spectroscopy was used for a facile assignment of the cyclization regioisomers, a combination of homo (proton–proton) and heteronuclear (proton–fluorine) NOE experiments allowed the determination of the relative configuration on stereogenic centres. The structure of some compounds was also confirmed by the X‐ray diffraction. Adaptation of the 1D double‐pulsed field‐gradient spin‐echo NOE for a heteronuclear case is presented. Copyright © 2010 John Wiley & Sons, Ltd.     

Oxidation of menthone oxothiolane

meta-Chloroperoxybenzoic acid (m-ClPBA) was shown to be an oxidant for two stereoisomers of menthone oxothiolane. The effect of steric factors on the ability to oxidize the sulfide group was found. Oxidation of (5S,6S,9R)-6-isopropyl-9-methyl-1-oxo-4-thiaspiro[4.5]-decane to the sulfone was prevented by the steric proximity of an isopropyl group to the S atom in the oxothiolane ring. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 588–590, November–December, 2008.     

5,6-二亚甲基二环[2.2.1]庚-2-醇的四种立体异构体的合成与构型

本文报道了手性桥环化合物5,6-二亚甲基二环[2.2.1]庚-2-醇的四种光学纯立体异构体的合成及其比旋光度[α]~D, 并通过它们之间的相互关系, 确定了它们的绝对构型.     

Reststereoisomere Tricarbonylchrom-Komplexe — eine Möglichkeit zur Enantiomerentrennung von torsionsisomeren Benzolderivaten

The complexation of C₁- or C₂-symmetrical torsional isomeric benzene derivatives may result in residual stereoisomeric complexes if the ligand is converted to its enantiomer by the torsional motion and if the complexation site is not within the symmetry axis (C₂ axis). The resulting residual stereoisomers are well suited for optical resolution, especially if the equilibrium is strongly in favor of one isomer.

     

Reaction of stereoisomeric bis(cyclohexyl)-2,2′-diones with hydrogen peroxide: structure of the formed adducts

The reaction ofmeso- andD,L-forms of bis(cyclohexyl)-2,2-dione with a methanol solution of hydrogen peroxide in a neutral medium has been studied. It has been established that in the case of theD,L-formrac-(1R,4R,9S,10S)-1,4-dihydroxy-2,3-dioxatricyclo-[8.4.0.0^4,9] tetradecane is formed, while themeso-form affordsrac-(1R,4R,9S,10R)-1-methoxy-4-hydroxy-2, 3-dioxatricyclo[8.4.0.0^4,9]tetradecane. The structures of the compounds have been established by X-ray structural analysis and by¹H and¹³C NMR spectroscopy.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 934–939, May, 1995.This work was financially supported by the International Science Foundation (Grant M04 000), the American Crystallographic Association, and the Russian Foundation for Basic Research (Project No. 94-03-09189).     

HP-β-环糊精对盐酸舍曲林异构体手性选择包合和色谱保留行为影响的研究

研究了不同色谱条件下HP-β-环糊精(HP-β-CD)作为反相高效液相色谱(RP-HPLC)手性添加剂对盐酸舍曲林异构体的手性选择性和色谱保留行为的影响。通过保留因子(k)的倒数1/k对［HP-β-CD］的良好线性关系证明HP-β-CD与盐酸舍曲林异构体形成了包合比为1∶1的包合物,并通过1/k对［HP-β-CD］的直线求得其结合常数。同时系统研究了pH值、缓冲液浓度(离子强度)、乙腈溶剂强度及温度对结合常数的影响,对结合常数与它们的关系做出了定量的描述;计算了手性分离过程中的热力学参数,并结合所计算的结     

Structural analysis of chiral complexes of palladium(0) with 15-membered triolefinic macrocyclic ligands

The complete structural analysis of the palladium complexes of the triolefinic macrocycles (E,E,E)-1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-trienes, which featured from three identical to three different aryl groups, was achieved by performing X-ray diffraction studies, NMR spectroscopy, and other calculations. The stereochemical complexity is determined by the different isomers formed through complexation of the metal to one or other face of each of the three olefins involved. The palladacyclopropane formulation of the palladium-olefin interaction offers a clear picture of the stereogenicity of the olefin carbon atoms that are complexed to the metal. The energetically favorable isomers were identified in the solid-state and in solution by performing X-ray diffraction and NMR spectroscopic analysis, respectively.     

A Cheminformatics Study Regarding the Human Health Risks Assessment of the Stereoisomers of Difenoconazole

Difenoconazole is a chemical entity containing two chiral centers and having four stereoisomers: (2R,4R)-, (2R,4S)-, (2S,4R)- and (2S,4S)-difenoconazole, the marketed product containing a mixture of these isomers. Residues of difenoconazole have been identified in many agricultural products and drinking water. A computational approach has been used to evaluate the toxicological effects of the difenoconazole stereoisomers on humans. It integrates predictions of absorption, distribution, metabolism, excretion and toxicity (ADMET) profiles, prediction of metabolism sites, and assessment of the interactions of the difenoconazole stereoisomers with human cytochromes, nuclear receptors and plasma proteins by molecular docking. Several toxicological effects have been identified for all the difenoconazole stereoisomers: high plasma protein binding, inhibition of cytochromes, possible hepatotoxicity, neurotoxicity, mutagenicity, skin sensitization potential, moderate potential to produce endocrine disrupting effects. There were small differences in the predicted probabilities of producing various biological effects between the distinct stereoisomers of difenoconazole. Furthermore, there were significant differences between the interacting energies of the difenoconazole stereoisomers with plasma proteins and human cytochromes, the spectra of the hydrogen bonds and aromatic donor–acceptor interactions being quite distinct. Some distinguishing results have been obtained for the (2S,4S)-difenoconazole: it registered the highest value for clearance, exposed reasonable probabilities to produce cardiotoxicity and carcinogenicity and negatively affected numerous nuclear receptors.     

Identification of Pt(II) and Pd(II) stereoisomeric complexes with aminobutyric acid by NMR and IR spectroscopy

Complexes of Pd(II) with aminobutyric acid AmH = NH₂CH(CH₂CH₃)COOH, namely, trans-[Pd(AmH)₂Cl₂] with monodentate (via the NH₂ group) AmH ligands and cis-, trans-Pd(Am)₂ with bidentate (via NH₂ and COO groups) ligands have been synthesized for the first time. Elemental analysis and IR and NMR spectroscopy were used to identify the synthesized compounds. The NMR spectra of the Pd(II) complexes were interpreted by comparing them with the NMR spectra of the analogous complexes of Pt(II). For Pt(II) and Pd(II) complexes with aminobutyric acid used as examples, an approach to identification of diastereomer bis-aminoacid complexes in specimens with racemic aminoacids by NMR spectroscopy is demonstrated.