共查询到20条相似文献,搜索用时 31 毫秒
1.
Vyacheslav E. Platonov Alois Haas Meinolf SchelvisMax Lieb Kira V. DvornikovaOlga I. Osina Tatyana V. RybalovaYuri V. Gatilov 《Journal of fluorine chemistry》2002,114(1):55-61
N-Methyl-, N-n-butyl-, N-t-butylperfluoroarylamines undergo nitrosation with nitrous acid to give the corresponding N-nitroso derivatives. Perfluoroaryl groups were selected from the benzene, indane, biphenyl, naphthalene and pyridine series. According to 1H and 19F NMR spectra, N-nitroso-N-methyl derivatives of polyfluoroarenes consist of E and Z isomers with the former prevailing. The more bulky n-butyl group promotes an increase in the formation of Z isomers. Only Z isomers have been obtained from N-t-butyl derivatives of perfluorinated 4-toluidine and 4-aminopyridine. The structure of the Z isomer of N-nitroso-N-methylperfluoro-4-toluidine is confirmed by X-ray data. 相似文献
2.
Ugo Chiacchio Filippo Genovese Vito Librando Antonio Rescifina Antonio Procopio 《Tetrahedron》2004,60(2):441-448
A new class of homo-N,O-nucleosides has been designed, based on the 1,3-dipolar cycloaddition of C-substituted nitrones with allyl nucleobases. The N-methyl-C-ethoxycarbonyl nitrone 1, and the C-α-silyloxymethyl-N-methyl nitrone 7 have been exploited: the stereochemical features of the obtained nucleosides are dependent on the nature of the dipole. The results obtained with DFT calculations fully agree with the experimental results and successfully reproduce the experimentally observed reversal of endo/exo selectivity for nitrones 1 and 7. 相似文献
3.
Nermeen A. Eltahawy Amany K. Ibrahim Mohamed M. Radwan Mahmoud A. ElSohly Hashim A. Hassanean Safwat A. Ahmed 《Tetrahedron letters》2014
Chemical investigation of the Red Sea soft coral Sarcophyton auritum led to the isolation and structure elucidation of two new diterpene cembranoids; 2-epi-sarcophine (2) and (1R,2E,4S,6E,8R,11R,12R)-2,6-cembradiene-4,8,11,12-tetrol (4), as well as two known diterpene cembranoids, reported for the first time from this species, namely sarcophine (1) and (+)-7α,8β-dihydroxydeepoxysarcophine (3). Structure elucidation was achieved using spectroscopic techniques, including 1D and 2D NMR and HRMS. The isolated cembranoids were found to display high cytotoxicity against HepG2 (liver cancer cell line) and MCF-7 (breast cancer cell line). 相似文献
4.
Conformational analyses of bicyclo[m.m.m]alkanes where m=1-10 and of bicyclo[8.8.n]alkanes where n=1-7 bearing methyl groups on the bridgeheads were carried out using a Monte Carlo search strategy. In the bicyclo[m.m.m]alkane series, greater variability was observed for the inter-bridgehead distance for larger values of m. This suggests that properly substituted bicyclo[8.8.8]hexacosanes or larger ring systems might serve as molecular springs. 相似文献
5.
Michael Block Christoph Wagner Dirk Steinborn 《Journal of organometallic chemistry》2011,696(9):1768-1781
Reactions of ω-diphenylphosphinofunctionalized alkyl phenyl sulfides Ph2P(CH2)nSPh (n = 1, 1a; 2, 2a; 3, 3a), sulfoxides Ph2P(CH2)nS(O)Ph (n = 1, 1b; 2, 2b; 3, 3b) and sulfones Ph2P(CH2)nS(O)2Ph (n = 1, 1c; 2, 2c; 3, 3c) with dinuclear chlorido bridged rhodium(I) complexes [(RhL2)2(μ-Cl)2] (L2 = cycloocta-1.5-diene, cod, 4; bis(diphenylphosphino)ethane, dppe, 5) afforded mononuclear Rh(I) complexes of the type [RhCl{Ph2P(CH2)nS(O)xPh-κP}(cod)]1 (n/x = 1/0, 6a; 1/1, 6b; 1/2, 6c; 2/0, 8a; 2/1, 8b; 2/2, 8c; 3/0, 10a; 3/1, 10b; 3/2, 10c) and [RhCl{Ph2P(CH2)nS(O)xPh-κP}(dppe)] (n/x = 1/0, 7a; 1/1, 7b; 1/2, 7c; 2/0, 9a; 2/1, 9b; 2/2, 9c; 3/0, 11a; 3/1, 11b; 3/2, 11c) having the P^S(O)x ligands κP coordinated. Addition of Ag[BF4] to complexes 6-11 in CH2Cl2 led with precipitation of AgCl to cationic rhodium complexes of the type [Rh{Ph2P(CH2)nS(O)xPh-κP,κS/O}L2][BF4] having bound the P^S(O)x ligands bidentately in a κP,κS (13a-18a, 15b-18b) or a κP,κO (13b, 14b, 13c-18c) coordination mode. Unexpectedly, the addition of Ag[BF4] to 6a in THF afforded the trinuclear cationic rhodium(I) complex [Rh3(μ-Cl)(μ-Ph2PCH2SPh-κP:κS)4][BF4]2·4THF (12·4THF) with a four-membered Rh3Cl ring as basic framework. Addition of sodium bis(trimethylsilyl)amide to complexes 6-11 led to a selective deprotonation of the carbon atom neighbored to the S(O)x group (α-C) yielding three different types of organorhodium complexes: a) Organorhodium intramolecular coordination compounds of the type [Rh{CH{S(O)xPh}CH2CH2PPh2-κC,κP}L2] (22a-c, 23a-c), b) zwitterionic complexes [Rh{Ph2PCHS(O)xPh-κP,κS/O}L2] having κP,κS (21a, 21b) and κP,κO (20b/c, 21c) coordinated anionic [Ph2PCHS(O)xPh] ligands, and c) the dinuclear rhodium(I) complex [{Rh{μ-CH(SPh)PPh2-κC:κP}(cod)}2] (19). All complexes were fully characterized spectroscopically and complexes 15b, 15c, 12·4THF and 19·THF additionally by X-ray diffraction analysis. DFT calculations of zwitterionic complexes gave insight into the coordination mode of the [Ph2PCHS(O)Ph] ligand (κP,κS versus κP,κO). 相似文献
6.
Humberto E. Ortega Young Yongchun Shen Karen TenDyke Nivia Ríos Luis Cubilla-Ríos 《Tetrahedron letters》2014
A new polyhydroxylated macrolide, named mangiferaelactone (1) was isolated from a solid culture of the endophytic fungus Pestalotiopsis manguiferae, together with ten known compounds [(6S,1′S)-LL-P880α; (6S,1′S,2′R)-LL-P880β; (1′S,2′R)-LL-880γ; (1′R)-dehydropestalotin; (−)-5-carboxylmellein; (−)-5-methylmellein; (−)-5-hydroxylmethylmellein; arabenoic acid; 5,6-dihydro-4-methoxy-2H-pyran-2-one; and the (−)-2-hexylidene-3-methylsuccinic acid]. P. manguiferae was isolated from Hyptis dilatata, a small shrub common in the central region of Panama. The structure of compound 1 was elucidated by a combination of spectroscopic methods (IR, MS, optical rotation, 1D and 2D NMR spectroscopy). The absolute configuration of 1 was established as 4R,7R,8R,9S by application of vibrational circular dichroism (VCD). Compound 1 showed a minimum inhibitory concentration (MIC) of 1.6863 mg/mL against Listeria monocytogenes, and 0.5529 mg/mL against Bacillus cereus. No activity was observed for compound 1 against Plasmodium falciparum or Trypanosoma cruzi; likewise, no cytotoxic activity was observed against A2058 and H522-T1 cells. 相似文献
7.
Biotransformation of (+)-(1R,2S)-fenchol by the larvae of Spodoptera litura was carried out. Substrate was converted to three new terpenoids, (+)-(1R,2S)-10-hydroxyfenchol, (+)-(1R,2R,3S)-8-hydroxyfenchol and (−)-(1S,2S,6S)-6-exo-hydroxyfenchol, and one known terpenoid, (−)-(1R,2R,3R)-9-hydroxyfenchol. These structures were established by NMR, IR, specific rotation and mass spectral studies. 相似文献
8.
High-performance liquid chromatography (HPLC) was employed in the fingerprint analysis of Angelica sinensis (Oliv.) Diels. A chromatographic profile of A. sinensis (Oliv.) Diels from the Dingxi District of Gansu province, China, was established as the characteristic fingerprint. The feasibility and advantages of employing chromatographic fingerprint combined with discriminant analysis were investigated and demonstrated for the evaluation of A. sinensis (Oliv.) Diels for the first time. Our results showed that the chromatographic fingerprint combining with discriminant analysis can efficiently distinguish A. sinensis (Oliv.) Diels from various areas. 相似文献
9.
N-Benzylamides were debenzylated efficiently with 4 equiv. of p-TsOH in refluxing toluene. Good to quantitative yields of the desired primary amides were obtained within 2-4 h from a wide variety of N-2,4-dimethoxybenzylamides. N-4-Methoxylbenzyl amides and N-benzylamides were also debenzylated cleanly. In the case of N-2,4-dimethoxylbenzylamides, selective N-debenzylation was possible in the presence of N-Fmoc, N-t-BOC or N-trityl-protection. Protected amino acid amides survived these conditions without any detectable epimerization. 相似文献
10.
Gregory L. FondongEdmond Y. Njua Alexander SteinerCharles F. Campana Lothar Stahl 《Polyhedron》2011,30(17):2856-2862
Syntheses and solid-state structures of zinc and tin(II) compounds, containing the N-silyl-amide ligands (OtBu)(NR)SiMe2, R = tBu (LtBu), or R = p-tolyl (LpTol), are reported. The N-silyl amines were synthesized by modified published procedures from commercially available Me2SiCl2, tBuOH, and tBuNH2, or p-Me-C6H4NH2, respectively. Treatment of SnCl2 with LiLpTol furnished Sn(LpTol)2, which was X-ray structurally characterized and shown to contain two covalent Sn-N bonds and two asymmetrical O → Sn donor bonds. The single-crystal X-ray structure of Sn(LtBu)2 revealed a much more symmetrically-coordinated, pseudo-trigonal-bipyramidal tin atom. Aminolysis of diethylzinc with HLpTol produced [EtZn(LpTol)]2, which crystallized as a centrosymmetric dimer, containing four-coordinate zinc atoms connected by bridging amides. Zinc dichloride, by contrast, reacted with two equivalents of LiLtBu to produce the homoleptic, pseudo-spirocyclic Zn(LtBu)2. 相似文献
11.
Takeshi Yamamoto Hideo UjiharaShinya Watanabe Makoto HaradaHiroyuki Matsuda Toshimitsu Hagiwara 《Tetrahedron》2003,59(4):517-524
The synthesis characterized by cationic olefin cyclizations accomplished using ketone enol esters and odor of novel (1R,6S)- and (1S,6R)-2,2,6-trimethylcyclohexyl methyl ketones (5) are described. The stereoselective syntheses of (E)-(1R,6S)- and (E)-(1S,6R)-1-(2,2,6-trimethylcyclohexyl)-2-buten-1-one (6) and (1R,6S)-ethyl 2,2,6-trimethylcyclohexylcarboxylate (7), useful raw materials for flavor and fragrance, starting from the (1R,6S)- and (1S,6R)-5 are also described. 相似文献
12.
Nikolai V Ignat’ev Michael SchmidtUdo Heider Andriy KucherinaPeter Sartori Fatiah M Helmy 《Journal of fluorine chemistry》2002,113(2):201-205
The electrochemical fluorination (ECF) of N,N-dimethylperfluoroacylamides gives the corresponding perfluoro-N,N-dimethylacylamides in low yield. With increase of the number of carbon atoms in the perfluoroacyl radical the yield of the required perfluoro-N,N-dimethylacylamides is slightly increased. 相似文献
13.
Sebastien Meiries 《Tetrahedron》2009,65(15):2951-2958
The divergent syntheses of the trichloroacetamide derivatives of (2S,3R,8R,9R,4E,6E)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-decadenoic acid (enantio-iso-ADDA), and (2R,3R,8R,9R,4E,6E)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-decadenoic acid (enantio-ADDA), have been achieved. Our approach takes advantage of highly efficient non-aldol aldol, palladium catalysed aza-Claisen and cross-metathesis methodologies. 相似文献
14.
Alkyl and dialkylammonium tetrafluoroborate promoted cis-trans isomerization of 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane (1) in DMSO-d6 were studied. The isomerization equilibrium constant K are within the range of 3.74-3.30 from 22 to 47 °C. Thermodynamic parameters of ΔH° and ΔS° for the isomerization were −0.95 kcal/mol and −0.59 cal/mol-K respectively. The isomerization rate is first order in [cis-1] and second order in [RnNH4−nBF4]. Both components of RnNH4−n+ and BF4− are essential for the catalytic cis-trans isomerization. The catalytic strength follows the decreasing order of +H3N(CH2)6NH3+>n-C8H17NH3+>n-C16H33NH3+>Me3CNH3+>PhCH2NH3+>Et2NH2+?Ph2CHNH3+, Et3NH+. Inversion region was observed in the plot of ln(kf/T) versus (1/T) with the ceiling located at around 38 °C. The positive activation enthalpy of 9 kcal/mol was estimated at 22-32 °C. The activation enthalpy turns to be slightly negative at T>38 °C. 相似文献
15.
N,N,N′,N′-Tetramethylmethanediamine (1a), N,N,N′,N′-tetramethylethanediamine (1b), N,N,N′,N′-tetramethyl-1,3-propanediamine (1c), and N,N,N′,N′-tetramethyl-1,6-hexanediamine (1d) were reacted at 25 °C with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (2a), 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (2b), 2-thenoyltrifluoroacetone (2c), and 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (2d) to form the ionic adducts 3-18. 1,4,7,10-Tetraazacyclododecane (1e) reacted at 25 °C with β-diketones (2a-d) and 1,1,1-trifluoro-2,4-pentanedione (2e) to give ionic solids 19-23 in good yields. Some of the products are liquid at 25 °C and are thermally stable over long liquid ranges as determined by thermal gravimetric analyses. Single-crystal X-ray structure determinations show that compounds 9 and 21 crystallize in the monoclinic space groups P2(1)/c and P2(1)/n, respectively. All the new compounds were characterized by 1H, 19F and 13C NMR, electrospray MS and/or elemental analyses. 相似文献
16.
Jun Mifune 《Polymer Degradation and Stability》2010,95(8):1305-1312
Cupriavidus necator H16CAc, previously constructed for production of poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) [P(3HB-co-3HHx)] from soybean oil, was further engineered aiming to increase 3HHx composition in the copolyester. PHA synthase gene derived from Aeromonas caviae on the H16CAc chromosome was replaced by a gene encoding the N149S/D171G mutant and this recombination enhanced PHA productivity as well as slightly increased 3HHx composition. Manipulation of phaACn locus partially reduced the amount of 3HB unit concomitantly with relative increase of 3HHx composition, whereas deletion of phaB1Cn resulted in drastic decline of 3HB unit in P(3HB-co-3HHx). Insertion of phaJAc encoding (R)-specific enoyl-CoA hydratase from A. caviae into pha operon significantly enlarged 3HHx fraction without negative effects on the cell growth and polyester accumulation. Consequently, efficient production of P(3HB-co-3HHx) with 3HHx composition of 5.7-9.9 mol% was successfully achieved from soybean oil by the engineered strains. 相似文献
17.
Sousuke Hara 《Tetrahedron》2004,60(37):8031-8035
The stereocontrolled synthesis of the protected (2S,3S)-N-methyl-5-hydroxyisoleucine, a component of halipeptins A and B with potent anti-inflammatory activity, has been achieved. The key steps include (i) installation of a double bond to bicyclic lactam 4 using N-tert-butyl phenylsulfinimidoyl chloride, (ii) highly exo-selective Michael reaction with lithium dimethylcuprate in the presence of chlorotrimethylsilane, and (iii) Ru-catalyzed oxidative deprotection of N,O-benzylidene acetal to the acid anhydride. 相似文献
18.
Renquan Zeng Xiangkai Fu Xinbin Yang Jingrong Chen 《Journal of organometallic chemistry》2008,693(16):2666-2672
Layered zirconium benzylamino-N,N-dimethylphosphonate phosphate (ZBMPA) was prepared by the reaction of zirconyl chloride with benzylamino-N,N-dimethylphosphonic acid (H2BMPA) and phosphoric acid in the presence of hydrofluoric acid. The intercalation of n-alkylamines (n-butylamine, n-heptylamine and n-decylamine) into ZBMPA was primarily investigated at room temperature. These materials were characterized by elemental analysis, ICP, XRD, SEM, FT-IR, Raman spectra, TG and DSC. The composition of ZBMPA is Zr(HPO4)(C6H5CH2N(CH2PO3)2)0.5 · 2.0H2O. The interlayer distance of ZBMPA, n-butylamine, n-heptylamine and n-decylamine intercalation compounds is 2.03, 2.58, 2.52 and 3.17 nm, respectively. ZBMPA and the n-alkylamine intercalation compounds are different in the morphology and vibration spectra. Thermogravimetries of all materials obtained reveal three step mass losses at temperatures of up to 1000 °C. These results indicate that n-alkylamines are intercalated into the galleries of host ZBMPA. 相似文献
19.
Thomas A. Ramirez 《Tetrahedron letters》2010,51(14):1822-20900
A dehydrogenation method using Cu(I) and either N,N-di-tert-butylthiadiaziridine 1,1-dioxide or N,N-di-tert-butyldiaziridinone is reported. The dehydrogenation allows a facile introduction of C-C double bond(s) into various carbocycles and heterocycles such as oxazolines and thiazolines. 相似文献
20.
J. HrenovicD. Kovacevic T. Ivankovic D. Tibljas 《Colloids and surfaces. B, Biointerfaces》2011,88(1):208-214
The immobilization of desired bacteria onto material was usually performed in synthetic media. The aim of this study was to test the immobilization of phosphate (P)-accumulating bacteria Acinetobacter junii onto natural zeolitized tuff (NZ) in the raw or sterilized municipal wastewater containing the common bacteria Escherichia coli and Enterococcus faecalis and the performance of immobilized A. junii in the same type of wastewater. In the sterilized wastewater which contained the mixture of A. junii, E. coli and E. faecalis, the A. junii was selectively immobilized onto NZ in significantly higher numbers than E. coli and E. faecalis. The A. junii added in the form of bioparticles to the wastewater containing E. coli and E. faecalis, multiplied and removed P from wastewater. The P removal from wastewater was a function of biomass of P-accumulating bacteria and not the amount of NZ or bioparticles used. The performance of A. junii was significantly better in membrane filtered than in autoclaved wastewater. The experiments that were performed in raw non sterilized wastewater showed that A. junii can be successfully immobilized onto NZ in competition with natively present heterotrophic bacteria, retain its metabolic activity and successfully remove P from such water, which makes this technology feasible from biotechnological aspect. 相似文献