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1.
Summary. We describe the formation of thieno[2,3-b:5,4-c]dipyridines from 5,6-dihydropyridine-2(1H)-thiones. The two-step reaction mechanism was revealed by isolation of an intermediate. The oxo and thioxo groups of the obtained tricyclic compounds were hydrogenated selectively. The structures of all new compounds were elucidated by NMR experiments.Received December 17, 2002; accepted December 20, 2002
Published online June 2, 2003 相似文献
2.
Summary. Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates with ethyl 2-(1-naphthylamino)-2-oxoacetate, leads to a vinylphosphonium salt, which undergoes intramolecular Wittig reaction to produce dialkyl 4-ethoxy-1-(1-naphthyl)-5-oxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylates in excellent yields. A dynamic NMR effect is observed in the 1H NMR spectra of the title compounds as a result of restricted rotation around the single bond linking the naphthalene moiety and the heterocyclic system, which is attributed to the peri interaction between the pyrrole residue and the peri CH group. The free energy of activation (G
) for this process is 58±2kJmol–1.Received December 6, 2002; accepted December 11, 2002
Published online June 12, 2003 相似文献
3.
Diwischek Florian Heller Eberhard Holzgrabe Ulrike 《Monatshefte für Chemie / Chemical Monthly》2003,134(8):1105-1111
Summary. By reaction of aromatic aldehydes with (-)-ephedrine aromatic 1,3-oxazolidines can be obtained. The reaction was carried out either at conventional conditions or by microwave heating. The different diastereomeric ratios were determined by means of 1H NMR spectroscopy.Received December 19, 2002; accepted December 23, 2002
Published online June 2, 2003 相似文献
4.
Krishna C. Majumdar Uday K. Kundu Swapan K. Samanta Nirmal K. Jana 《Monatshefte für Chemie / Chemical Monthly》2003,134(8):1137-1143
Summary. Two hitherto unreported pyrimidine annelated heterocycles were synthesized from 6-cyclopent-2-enyl-5-hydroxy-1,3-dimethylpyrimidine-2,4(1H,3H)-dione and 5-cyclopent-2-enyl-6-hydroxy-1,3-dimethylpyrimidine-2,4(1H,3H)-dione by reaction with pyridine hydrotribromide or hexamethylenetetramine hydrotribromide. The first one was also obtained by reaction with concentrated sulfuric acid.Received October 28, 2002; accepted October 30, 2002
Published online June 2, 2003 相似文献
5.
Summary. Group 2B transition metal complexes of bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (o,o-iPr2C6H3-BIAN), namely, [Hg(o,o-iPr2C6H3-BIAN)Cl2] (1), [Zn(o,o-iPr2C6H3-BIAN)2](ClO4)2 (2), and [Cd(o,o-iPr2C6H3-BIAN)2](ClO4)2 (3) have been synthesized and characterized. In complexes 2 and 3, IR, NMR, and conductivity measurements confirm the coordination of two (o,o-iPr2C6H3-BIAN) ligands to the metal center with two discrete perchlorate anions. X-Ray crystal structure of 1 indicates a distorted tetrahedral geometry with two nitrogen atoms from (o,o-iPr2C6H3-BIAN) ligand and two chloride atoms coordinating to the Hg(II) center. 相似文献
6.
Summary. Several ruthenium procatalysts were tested in the transfer hydrogenation of acetophenone with 2-propanol using the chiral imine ligand (S)-2-(2-pyridinylmethyleneamino)-2-hydroxy-1,1-binaphthyl and the corresponding amine (S)-2-(2-pyridinylmethylamino)-2-hydroxy-1,1-binaphthyl. Ru(PPh
3)3Cl2 was the best procatalyst. Its triphenylphosphane ligands were crucial for the catalytic activity and take part in the chirality transfer. Triphenylphosphane removing reagents such as copper(I) chloride, TEMPO, or TMAO improved the catalytic performance to enantioselectivities up to 99% ee. The findings led to a mechanistic proposal including dissociation equilibria of triphenylphosphane and chelate ring opening of the tridentate chiral binaphthyl ligand. New ligands with an additional chiral center were synthesized and tested as cocatalysts. The nature of catalytically active intermediates was examined by MS and NMR spectroscopy. 相似文献
7.
Frassineti C Alderighi L Gans P Sabatini A Vacca A Ghelli S 《Analytical and bioanalytical chemistry》2003,376(7):1041-1052
The pKa values of 6-fluoro-4,8-diazadodecane-1,12-diamine (6-fluorospermine) (1), 6,6-difluoro-4,8-diazadodecane-1,12-diamine (6,6-difluorospermine) (2), 6-fluoro-4-azaoctane-1,8-diamine (6-fluorospermidine) (3) and 6,6-difluoro-4-azaoctane-1,8-diamine (6,6-difluorospermidine) (4) in D2O solution have been determined at 40 °C from 13C NMR chemical shifts data using the new computer program HypNMR2000. The enthalpies of protonation of compounds 1–4 and the parent amines spermine (5) and spermidine (6) have been determined from microcalorimetric titration data. The values of H° were used to derive basicity constants relative to 25 °C. The NMR data have been analysed by two different methods to obtain information on the protonation sequence in the polyamines 1–5. The protonation sequence for spermine is related to its biological activity.Abbreviations PKC Protein kinase C - PS Phosphatidylserine - VB Microsoft Visual BasicPresented at the Spanish-Italian Congress on the Thermodynamics of Metal Complexes, Santiago de Compostela, Spain, June 2–6, 2002 相似文献
8.
Summary. The reaction of [RuCp(CH3CN)3]PF6 with 1 equiv of N-Me-imidazole results in the quantitative formation of [RuCp(1N-N-Me-imidazole)(CH3CN)2]PF6 (1) featuring a 1N rather than a 1C bound N-Me-imidazole ligand. According to DFT/B3LYP calculations, 1N coordination of N-Me-imidazole is preferred over 1C coordination by 25.5kJ/mol. Upon exposure to air 1 reacts with oxygen and water to afford the novel hydroxo-bridged dinuclear complex of [Ru2Cp2(1N-N-Me-imidazole)2(-OH)2](PF6)2 (2) featuring a metal-metal single bond. The dimeric nature of 2 was confirmed by a single-crystal X-ray structure analysis. 相似文献
9.
Summary. The gadolinium–rhodium–indide Gd3Rh1.940(7)In4 was prepared by arc-melting of the elements and subsequent annealing in a corundum crucible in a sealed silica tube. Gd3Rh1.940(7)In4 adopts the hexagonal Lu3Co1.87In4 type, space group
, a = 781.4(5), c = 383.8(3) pm, wR2 = 0.0285, BASF = 0.375(1) (merohedric twinning via a twofold axis (xx0)), 648 F2 values, 22 variables. The structure is derived from the well known ZrNiAl type through an ordering of rhodium and indium
atoms on the Ni2 sites. The Rh/In ordering forces a reduction of the space group symmetry from
to
, leading to merohedric twinning for the investigated crystal. The Rh1 site has an occupancy of only 94.0(7)%. The investigated
crystal had a composition Gd3Rh1.940(7)In4. The main geometrical motif are three types of centered, tricapped trigonal prisms, i.e., [Rh1In26Gd3], [Rh2Gd6In23], and [In1Gd6In23]. The shortest interatomic distances occur for Rh–In (276–296 pm) followed by In–In (297 pm). Together, the rhodium and indium
atoms build up a three-dimensional [Rh1.940(7)In4] network, in which the gadolinium atoms fill slightly distorted pentagonal channels. The crystal chemistry of Gd3Rh1.940(7)In4 is discussed on the basis of a group-subgroup scheme. 相似文献
10.
V. N. Elokhina A. S. Nakhmanovich T. N. Komarova R. V. Karnaukhova O. B. Bannikova V. A. Lopyrev Yu. T. Struchkov O. V. Shishkin K. A. Potekhin 《Russian Chemical Bulletin》1996,45(12):2823-2826
3-Acyl-6-methyl-5H-thiazolo[2,3-c][1,2,4]triazines were synthesized by reaction of 1-acyl-2-bromoacetylenes with 6-methyl-3-thioxo-1,2,4-triazin-5-one in methanol in the presence of triethylamine at 20 °C. The structure of 3-benzoyl-6-methyl-5H-thiazolo[2,3-c][1,2,4]triazine was established by X-ray structural analysis. Substituted 3-(2-acetylvinylthio)1,2,4-triazin-5-ones were obtained by the reaction of -acetylenic ketones with 6-methyl-3-thioxo-1,2,4-triazin-5-one under the same conditions. The structures of the new compounds were confirmed by IR,1H, and13C NMR spectroscopy.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2971–2975, December, 1996. 相似文献
11.
A series of 3‐[(6‐chloropyridin‐3‐yl)methyl]‐6‐substituted‐6,7‐dihydro‐3H‐1,2,3‐triazolo[4,5‐d]pyrimidin‐7‐imines were designed and synthesized via a multi‐step sequence using 2‐chloro‐5‐(chloromethyl)‐pyridine as the starting material. Various primary aliphatic amines, hydrazine and hydrazide reacted with 3 to obtain the cyclization products 4 . Their structures were confirmed by 1H NMR and elemental analyses, some of them were also confirmed by IR, 13C NMR, MS and single crystal X‐ray diffraction. The preliminary bioassay indicated that some of the target compounds 4 displayed moderate to weak fungicidal activity and insecticidal activity. 相似文献
12.
A. N. Grinev G. M. Borodina G. V. Yaroslavtseva L. M. Alekseeva 《Chemistry of Heterocyclic Compounds》1970,6(12):1525-1527
A number of 2-methyl-3-carbethoxy-5-hydroxy-6-arylindole derivatives were obtained by the condensation of aryl-p-benzoquinones with -aminocrotonate esters and N-substituted -aminocrotonate esters. The position of the aryl substituent was established by means of the NMR spectra.See [8] for Communication XLVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1634–1636, December, 1970. 相似文献
13.
László Somogyi Gyula Batta Tamás E. Gunda Attila Cs. Bényei 《Journal of heterocyclic chemistry》2008,45(2):489-495
Under acetylating conditions racemic thioflavanone thiosemicarbazones cyclize into racemic 3‐acetyl‐spiro[1,3,4‐thiadiazoline‐2,4′‐thioflavans] and a racemic 3‐acetylspiro[1,3,4‐oxadiazoline‐2,4′‐thioflavan] with trans O(1) or S(1) and Ph(2′eq). Hindered rotation of the endocyclic N(3) acetyl group spirothia‐diazolines caused the formation of isomers separable by HPLC. X‐ray diffraction analyses, 1H‐, 13C‐, and 15N NMR measurements as well as MOPAC QM calculations were performed to reveal the structures of these isomers. 相似文献
14.
Daisuke Taura Yosuke Taniguchi Akihito Hashidzume Akira Harada 《Macromolecular rapid communications》2009,30(20):1741-1744
Interaction of β‐cyclodextrin (β‐CD) with alternating copolymers (pAdMA and pAdPhMA) of sodium maleate with adamantyl (Ad) and with adamantylphenyl (AdPh) vinyl ether has been investigated by several NMR techniques. Comparing the apparent association constants (K) for the polymers with the K for the model compounds, which are determined by the analysis of 1H NMR and isothermal titration calorimetry data, respectively, the selectivities of β‐CD toward Ad and AdPh moieties are contrasting for the model and polymer systems. This phenomenon is described by circular dichroism and 2D NMR as follows; the most stable inclusion complex for the β‐CD/AdPh model system is extremely destabilized for the corresponding polymer system because of competition with hydrophobic interaction between neighboring AdPh moieties.
15.
Alaitz Ruiz de Luzuriaga Jos A. Pomposo Hans Grande Agustin Etxeberria 《Macromolecular rapid communications》2009,30(11):932-935
We have studied the kinetics of polymeric nanoparticle formation for poly(styrene‐block‐4‐vinylpyridine) [P(S‐b‐4‐VPy)], chains in a non‐selective solvent using 1,4‐dibromobutane (DBB) as a cross‐linker by means of different nuclear magnetic resonance (NMR) spectroscopy techniques. The kinetic process was followed using 1H, 13C, and 2‐D Heteronuclear Single Quantum Correlation (HSQC) NMR experiments. The kinetic data obtained from 2‐D HSQC and 1H NMR experiments were in good agreement between them, proving the reliability of the 2‐D HSQC NMR technique for the in situ study of the kinetics of core‐shell nanoparticle formation. A value of 1.5 × 10−5 s−1 was determined for the apparent kinetic constant of the P(S‐b‐4‐VPy)‐DBB core‐shell nanoparticle formation process.
16.
I. I. Kapustina L. P. Ponomarenko O. P. Moiseenko V. A. Stonik 《Chemistry of Natural Compounds》2001,37(6):515-519
NMR spectroscopy, capillary GLC, and GLC-MS are used to study the composition of free and sulfated sterols from the far-east starfishLeptasterias alaskensis asiatica(Fischer) andL. Fisheri(Djakonov). The total free sterols of both species are shown to have similar qualitative and quantitative compositions and contain mainly7
-sterols. Sterol sulfate fractions contain cholesterol sulfate as the main component but differ in the ratios of5
:0
:7
-sterol derivatives. Possible reasons for these differences are discussed. A new steroid, 3-hydroxycholest-5-en-7-one sulfate, was isolated. 相似文献
17.
Monika Wujec Agata Siwek Marta Swatko‐Ossor Liliana Mazur Zofia Rzaczynska 《Journal of heterocyclic chemistry》2008,45(6):1893-1896
By the reaction aminomethylation, chloromethylation and acylation of 4‐methyl‐4H‐1,2,4‐triazole‐3‐thiol, 4‐methyl‐1‐substituted‐1H‐1,2,4‐triazole‐5(4H)‐thione 1‐8 were obtained. Molecular structure of the obtained compounds was confirmed by an elemental analysis, IR, 1H NMR and 13C NMR spectra and additionally by X‐ray analysis for 2. Six new compounds 1,2,4‐7 were tested for antibacterial activity against Mycobacterium smegmatis, Mycobacterium phlei and avirulent strain Mycobacterium H37Ra. 相似文献
18.
K. F. Koehler H. Zaddach G. K. Kadorkina V. N. Voznesenskii I. I. Chervin R. G. Kostyanovsky 《Russian Chemical Bulletin》1993,42(12):2049-2052
The structure of azimexone (3), the product of the reaction of 2-cyanoaziridine with acetone, was confirmed on the basis of1H and13C NMR spectra. The formation of this product is accounted for by the -aziridinoalkylating action of an intermediate containing a good leaving iminoyloxy group. Similar reactions were observed for 1-chloromethylaziridine and a 1-aziridinylmethylammonium salt (6), but not for 1-methoxymethylaziridine (7) and 1-aziridinemethanol.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2136–2139, December, 1993. 相似文献
19.
Summary. (R,6R,7R)-7-(1-Acetoxyethyl)-3-methyl-2-isoxacephem-4-carboxylic acid and its enantiomer have been prepared. The ring systems were formed from the corresponding enantiomerically pure N-unsubstituted -lactams. The reduction of methyl [(R,2S,3R)-3-(1-acetoxyethyl)-1-(4-methoxyphenyl)-4-oxoazetidine-2-carboxylate] has been solved via a hemi-acetal. The structure and the configuration of a new stereogenic center in this intermediate was predicted by using 2D NMR technique and unambiguously proven by x-ray. 相似文献
20.
《Magnetic resonance in chemistry : MRC》2002,40(9):573-580
2‐Amino‐4‐fluoro‐2‐methylpent‐4‐enoic acid, obtained as a 1 : 1 salt with trifluoro‐acetic acid, was characterized by 1H and 19F high‐resolution NMR spectroscopy. High‐precision potentiometry led to the dissociation constants pK = 1.879 and pK = 9.054. The first automated 470.59 MHz 19F NMR‐controlled titration yielded the dynamic chemical shift 〈δF〉 as a function of pcH or τ and the ion‐specific chemical shifts: δF(H2L+) = ?94.81 ppm, δF(HL) = ?94.21 ppm, δF(L?) = ?92.45 ppm. The deprotonation gradients were found to be Δ1 = ?0.60 ppm and Δ2 = ?1.76 ppm. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献