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1.
Reaction of the triolide 1 from (R)-3-hydroxybutanoic acid with Lawesson's reagent 5 leads to the mono-, di-, and trithio derivatives 6–8 which can be isolated in pure form (20–40% yields), and which have crystal structures very similar to the parent triolide 1 (Fig. 1). Similarly, pentolide 3 is converted to mixtures of various thio derivatives, three of which are separated ( 10–12 ) by HPLC and fully characterized. The X-ray structures of the mono- and of one of the dithiopentolides ( 10, 12 ) differ remarkably from each other (Fig. 3). Reduction of the thiotriolides 6–8 (NaBH4, R3SnH, Cl3SiH, Raney-Ni) gives 12-membered rings containing up to three ether groups (chiral crown ethers, 15, 17–19 ) in poor yields. The thiotriolides react spontaneously and in yields of up to 96% with ammonia, certain primary amines, and hydroxylamine to give imine and oxime derivatives with intact 12-membered-ring backbones ( 20, 22–24, 30 , see crystal structures in Figs. 4–7). The rigid structure of all the derivatives of triolide 1 puts the C?O, C?S, and C?NR O-, S-, and N-atoms in juxtaposition (a feature reminiscent of the side chains in the iron-binder enterobactin, Fig. 6). Imines containing PPh2 groups are prepared ( 30, 33, 35 ) from the thiotriolides and tested as chiral ligands for PdII-catalyzed 1,3-diphenyallylations (→ 37 , enantiomer ratio up to 77:23). The reactions described demonstrate that multiple reactions of the triolide 1 from (R)-3-hydroxybutanoic acid which proceed through tetrahedral intermediates are possible without ring opening – the skeleton is remarkably stable, and this might be exploited as a template for bringing up to three pendent substituents into close proximity to allow a study of their interactions and cooperative properties. Also, the di- and trithio derivatives 7 and 8 could be used for cross-linking in molecules containing primary NH2 groups. 相似文献
2.
Hans-Jürgen Buschmann Radu-Cristian Mutihac Eckhard Schollmeyer 《Journal of solution chemistry》2009,38(2):209-217
The complex formation between different crown ethers and the cryptand [222] with alkali metal and ammonium ions in chloroform
has been investigated by means of calorimetric titrations. The stability constants, reaction enthalpies and entropies for
complex formation in chloroform have been determined. The complexation of alkali metal ions is favored by enthalpic contributions
and influenced by both the ligand and the nature of the cation. The reaction enthalpies for complex formation of different
ammonium salts with cryptand [222] are higher compared to the corresponding values for the reaction with different 18-crown-6
derivatives in chloroform due to the complete encapsulation of ammonium ion by the cryptand [222]. The benzo group attached
to the crown ethers and the nature of the anion borne by the ammonium ion influence complex formation of ammonium with crown
ethers. In the case of ammonium salts, competitive measurements have been carried out to underline the influence of the anion
upon the complex formation. From the reaction enthalpies for complexation of ammonium ions, the contributions for the formation
of hydrogen bonds are calculated using experimental data.
Taken in part from the Ph.D. thesis of R.-C. Mutihac, University Duisburg-Essen, 2007. 相似文献
3.
Bogachev N. A. Podryadrova K. A. Skripkin M. Yu. Mereshchenko A. S. 《Russian Journal of General Chemistry》2021,91(8):1604-1606
Russian Journal of General Chemistry - Electronic spectra of copper(II) phthalate complexes in non-aqueous solvents were obtained. Stability constants of the complexes were determined. It was shown... 相似文献
4.
Bolotin S. N. Frolov V. Yu. Panyushkin V. T. 《Russian Journal of General Chemistry》2004,74(2):219-221
Complex formation of copper(II) ions with the galactarate ion [Gala]2
- in aqueous solution was studied by means of potentiometric titration. Stability constants of the [CuGala] and [Cu(Gala)2]2
- complexes were determined. A complex compound was synthesized electrochemically and isolated from a DMSO solution containing a copper(II) salt and galactaric acid, and its composition was determined. The structure of the complex was determined by ESR. 相似文献
5.
采用沸石合成法,制备了封装M(phen)3(M=Fe,Co,Cr)配合物于Y型分子筛超笼中的复合催化材料,并利用XRD,FTIR,UV-vis,ICP的环己烷氧化反应等手段对其进行了表征。FT IR和UV-vis测试,有力地证明了合成产物中封装有M(phen)3配合物;XRD和ICP测试结果表明,在合成体系中引入不同的M(phen)3配合物,对Y型分子筛的晶化有不同的影响 相似文献
6.
K. C. Srivastava 《中国化学会会志》1976,23(4):229-232
The complex formation of Ytterbium (III) with Bromopyrogallol red has been studied. spectrophotometrically in an attempt to establish composition, stability, thermodynamic parameters and optimum conditions for determining small amounts of ytterbium. The violet complex of ytterbium has λmax at 620nm against a reagent blank. The composition determined by different methods is 1:1 at pH 6.2±0.1. The mean value of log K, free energy (ΔG), the heat content (ΔH) and entropy (ΔS) changes, of the complex are found to be 6.0, —8.1.kcal/mole, —3.5 Kcal/mole and 15.53 e.U. respectively at 30°C. The net molar absorptivity and Sandell's sensitivity is 19850 and 0.0087 μg of ytterbium /cm2. The effect of diverse ions was examined with thirteen cations and ten anions in the determination of ytterbium. 相似文献
7.
8.
Jack C. Kim Sang-Duk Bae Ji-A Kim Soon-Kyu Choi 《Journal of heterocyclic chemistry》1998,35(3):531-533
A Regioselective synthesis of (R)-11-hydroxyaporphine 2 directly from (R)-10,11-dihydroxyaporphine ((R)-apomorphine, 1 ) is described for the first time. The isopropylidene ketal ring of 10,11-(isopropyl-idenyldioxy)aporphine 5 obtained by the isopropylidenation of apomorphine was regioselectively opened by ten equivalents of trimethylaluminum to give (R)-10-hydroxy-11-tert-butyloxyaporphine 6 . The free 10-hydioxyl position of 6 was triflated with N-pbenyltrifluoromethanesulfonimide and potassium carbonate under reflux to give (R)-10-[(trifluoromethyl)sulfonyloxy]-11-tert-butyloxyaporphine 7 . The reduced product, 11-tert-butyloxyaporphine 8 was prepared from 7 by a palladium-catalyzed hydrogenolysis. The ether cleavage of (R)-11-tert-butyloxyaporphine with 48% hydrobromic acid afforded the desired (R)-11-hydroxyaporphine 2 in good yield. 相似文献
9.
10.
The synthesis of (R)-2,10-dihydroxyaporphine ( 3a ), (R)-2,10-dihydroxy-N-n-propylnoraporphine ( 3b ) from thebaine and (R)-2,11-dihydroxyaporphine (7), and 1,2,11-trihydroxyaporphine ( 9 ), from pukateine is reported. The rearrangement of thebaine and northebaine with methanesulfonic acid to 1a and 1b with subsequent N-propylation gave 1b . Tetrazolyation of 1a, 1b and hydrogenolysis of 2a and 2b on Pd/C in acetic acid with subsequent O-demethylation with hydrobromic acid (48%) led to 3a and 3b . R(-)-2,11-Dihydroxyaporphine ( 7 ) was prepared by lithium/ammonia reduction of pukateine. (R)-1,2,11-Trihydroxyaporphine ( 9 ) was synthesized by reaction of pukateine with boron tribromide in dichloromethane. 相似文献
11.
An improved procedure for the synthesis of either (R) or (S)-3-aminoquinuclidine was developed. Key intermediate imine 2 was made in a one pot process using lithium oxide as the base and molecular sieves. 相似文献
12.
《国际化学动力学杂志》2017,49(11):789-797
In this paper, the kinetics and mechanism of gold nanoparticles formation during the redox reaction between [AuCl4]− complex and l ‐ascorbic acid under different conditions were described. It was also shown that reagent concentration, chloride ions, and pH influence kinetics of nucleation and growth. To establish rate constants of these stages, the model of Finke and Watzky was applied. From Arrhenius and Eyring dependencies, the values of activation energy (22.5 kJ mol−1 for the nucleation step and 30.3 kJ mol−1 for the growth step), entropy (about −228 J K−1 mol−1 for the nucleation step and −128 J K−1 mol−1 for the growth step), and enthalpy (19.8 kJ mol−1 for nucleation and 27.8 kJ mol−1 for particles growth) were determined. It was also shown that the disproporationation reaction had influence on the rate of nanoparticles formation and may have impact on final particles morphology. 相似文献
13.
Gard Gjessing Lars-Inge Gammelster Johnsen Simen Gjelseth Antonsen Jens M. J. Nolse Yngve Stenstrm Trond Vidar Hansen 《Molecules (Basel, Switzerland)》2022,27(7)
Monohydroxylated polyunsaturated fatty acids belonging to the oxylipin class of natural products are present in marine and terrestrial sources as well as in the human body. Due to their biological activities and role in diverse biosynthetic pathways, oxylipins biosynthesized from eicosapentaenoic acid and arachidonic acid have attracted great interest from the scientific community. One example is 3-hydroxyeicosapentaenoic acid where the absolute configuration at C-3 has only been tentatively assigned. In this paper, studies on acetate type aldol reactions that enabled the preparation of 3-(R)-hydroxyeicosapentaenoic acid (3R-HETE, 2) and its enantiomer are presented. 相似文献
14.
15.
An efficient synthesis of (R)-7-(3-benzothienylamido)deacetoxy-cephalosporanic acid (1) is described beginning from (R)-alpha-aminobenzo[b]thiophene-3- acetic acid (2) and 7-amino-3-methyl-3-cephem-4-carboxylic acid (7-ADCA). Good yields were obtained and the procedure is amenable to multikilogram preparations. 相似文献
16.
Preparation of Amylose-Oligo[(R)-3-hydroxybutyrate] Inclusion Complex by Vine-Twining Polymerization
In this study, we attempted to prepare an amylose-oligo[(R)-3-hydroxybutyrate] (ORHB) inclusion complex using a vine-twining polymerization approach. Our previous studies indicated that glucan phosphorylase (GP)-catalyzed enzymatic polymerization in the presence of appropriate hydrophobic guest polymers produces the corresponding amylose–polymer inclusion complexes, a process named vine-twining polymerization. When vine-twining polymerization was conducted in the presence of ORHB under general enzymatic polymerization conditions (45 °C), the enzymatically produced amylose did not undergo complexation with ORHB. However, using a maltotriose primer in the same polymerization system at 70 °C for 48 h to obtain water-soluble amylose, called single amylose, followed by cooling the system over 7 h to 45 °C, successfully induced the formation of the inclusion complex. Furthermore, enzymatic polymerization initiated from a longer primer under the same conditions induced the partial formation of the inclusion complex. The structures of the different products were analyzed by X-ray diffraction, 1H-NMR, and IR measurements. The mechanism of formation of the inclusion complexes discussed in the study is proposed based on the additional experimental results. 相似文献
17.
18.
S. N. Gridchin 《Russian Journal of General Chemistry》2017,87(12):2846-2851
Complex formation of copper(II) ions with L-serine and L-homoserine at 298.15 K and ionic strength I 0.5, 1.0, and 1.5 (KNO3) has been studied by means of potentiometry and calorimetry. Standard thermodynamic parameters (log K0, ΔrG0, ΔrH0, ΔrS0) of the studied coordination equilibriums have been calculated. 相似文献
19.
Youyong Xu Andreas Walther Axel H. E. Müller 《Macromolecular rapid communications》2010,31(16):1462-1466
A supramolecular complex between an ionic monomer 3‐sulfopropyl methacrylate (SPMAK) and crown ether 18‐crown‐6 (18C6) has been employed to prepare a strong anionic cylindrical polyelectrolyte brush poly(potassium 3‐sulfopropyl methacrylate) (PSPMAK) by atom transfer radical polymerization (ATRP) in polar solvent dimethyl sulfoxide (DMSO). This strategy solved the problem of the solubilities of the incompatible hydrophobic poly‐initiator and hydrophilic ionic monomer. The formation of the PSPMAK brush is well proven by 1H NMR, aqueous gel permeation chromatography (GPC), dynamic light scattering (DLS), static light scattering (SLS), atomic force microscopy (AFM), and cryogenic transmission electron microscopy (cryo‐TEM) measurements. Cleavage of the side chains and further analysis reveal that the initiating efficiency of the polymerization is as low as 0.35.
20.
Jia‐Xiang Yang Ze Zhang Jie‐Ying Wu Yu‐Peng Tian Qing‐Liang Liu Hoong Kun Fun Anwar Usman Zbi‐Qiang Xu K. Thompson Laurence 《中国化学》2003,21(11):1461-1465
The synthesis and characterization of the copper (II) complex [Cu2(OOCCH = C(CH3)Fc)3(phen)2]CIO4 · 2H2O (1) are reported. The structure of the complex was determined by single‐crystal X‐ray analysis. The compound crystallizes in the monoclinic system, space group Pc, with Z =2, a = 1.2799(4) nm, b =0.9969 (4) nm, c = 2.5228 nm, and β = 91.576 (1) °. The cationic part of 1 indicates a penametallic core in which three 3‐ferrocenyl‐2‐crotonic acid salt (FCA) groups act as (O, O') bridging ligands between two copper (II) ions with a square‐pyramidal environment. Cyclic voltammetric experiments in acetonitrile have been performed mainly to examine the Fe(II) → Fe(III) one‐electron oxidation in FCA and its complex. The variable‐temperature magnetic susceptibility measurements revealed very weak intramolecular anti‐ferromagnetic coupling. Fitting parameters are 2J = ‐0.2 cm?1, g = 2.114, and θ = 0K. 相似文献