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1.
Ma Y Hoepker AC Gupta L Faggin MF Collum DB 《Journal of the American Chemical Society》2010,132(44):15610-15623
Lithium diisopropylamide (LDA) in tetrahydrofuran at -78 °C undergoes 1,4-addition to an unsaturated ester via a rate-limiting deaggregation of LDA dimer followed by a post-rate-limiting reaction with the substrate. Muted autocatalysis is traced to a lithium enolate-mediated deaggregation of the LDA dimer and the intervention of LDA-lithium enolate mixed aggregates displaying higher reactivities than LDA. Striking accelerations are elicited by <1.0 mol % LiCl. Rate and mechanistic studies have revealed that the uncatalyzed and catalyzed pathways funnel through a common monosolvated-monomer-based intermediate. Four distinct classes of mixed aggregation effects are discussed. 相似文献
2.
Structural and mechanistic studies of the lithium diisopropylamide (LDA)-mediated anionic Fries rearrangements of aryl carbamates are described. Substituents at the meta position of the arene (H, OMe, F) and the dialkylamino moiety of the carbamate (Me(2)N, Et(2)N, and i-Pr(2)N) markedly influence the relative rates of ortholithiation and subsequent Fries rearrangement. Structural studies using (6)Li and (15)N NMR spectroscopies on samples derived from [(6)Li,(15)N]LDA reveal an LDA dimer, LDA dimer-arene complexes, an aryllithium monomer, LDA-aryllithium mixed dimers, an LDA-lithium phenolate mixed dimer, and homoaggregated lithium phenolates. The highly insoluble phenolate was characterized as a dimer by X-ray crystallography. Rate studies show monomer- and dimer-based ortholithiations as well as monomer- and mixed dimer-based Fries rearrangements. Density functional theory computational studies probe experimentally elusive structural and mechanistic details. 相似文献
3.
《Physics and Chemistry of Liquids》2012,50(3):298-306
An ionic liquid (IL) containing an appended 3-chloro-2-hydroxypropyl functionality group 1-(3-chloro-2-hydroxypropyl)-3-methyl imidazolium chloride was synthesised by the reaction of N-methyl imidazole, hydrochloric acid and epichlorohydrin. The ionic liquid showed reasonably high conductivity and heat stability up to 230°C. Its structures were characterised by FT-IR, 1H NMR and 13C NMR spectra. The physical characteristics of the ionic liquid, such as conductivity and solvation abilities have been investigated. Due to its high polarity, the IL is able to dissolve many inorganic salts, and due to hydroxyl-rich microenvironment, it is able to dissolve cellulose go up to 10 (wt%). The ILs can be used for synthesising other ILs or polyelectrolyte. 相似文献
4.
The kinetics of solvolysis of the title compound has been studied in water and in 10 vol. % ethanol-water in the presence
and absence of mercury (II) chloride. The results confirm the earlier conclusion that mercury(II) chloride is solvated in
hydroxylic solvents.
Кинетика сольволиза заглавного соединения была исследована в воде и в смеси этанола (10 об.%) с водой в присутствии и отсутствии хлористой ртути (II). Реэультаты подтверждают более раннее заключение, согласно которому хлористая ртуть (II) сольватируется в гидроксильных растворителях.相似文献
5.
Sándor Kunsági-Máté István BitterAlajos Grün Géza Nagy László Kollár 《Analytica chimica acta》2002,461(2):273-279
The complexation behavior of the distally dialkylated calix[4]arenes and 4-tert-butylcalix[4]arenes (hosts) with 1-chloro-4-(trifluoromethyl)benzene (guest) was examined in four different alcohols (MeOH, EtOH, n-PrOH, n-BuOH) as solvents. The complex stability constants (Ks) and the complexation energy of the host-guest complexes were determined. Fair ‘by group’ linear correlations between each log K series determined in the same solvent and the complex stabilization energies were found. As a consequence, the solvents having high permittivities result in less stability of the host-guest complex in these particular cases examined. 相似文献
6.
通过改变传统氯虫酰胺中吡唑环上氨基甲酰基与吡啶环之间的相对位置, 或以其它芳环取代原分子中的吡啶环, 设计合成了24个结构新颖的N-[4-氯-2-取代氨基甲酰基-6-甲基苯基]-1-芳基-5-氯-3-三氟甲基-1H-吡唑-4-甲酰胺类化合物. 所有目标化合物的结构均通过1H NMR谱、 元素分析或高分辨质谱表征确定. 初步的生物活性测试结果表明, 部分化合物对东方粘虫具有较好的杀虫活性, 其中化合物6m在浓度为50 mg/L时具有80%的杀虫活性. 同时, 在浓度为50 mg/L时目标化合物对5种常见病菌具有明显的抑制作用, 其中化合物6n和6x对苹果轮纹菌的抑菌率达62.1%. 相似文献
7.
Olugbeminiyi O. Fadeyi 《Tetrahedron letters》2008,49(32):4725-4727
A simple synthesis of 5-(trifluoromethyl)cyclohexane-1,3-dione and 3-amino-5-(trifluoromethyl)cyclohex-2-en-1-one from the sodium salt of methyl or ethyl-4-hydroxy-2-oxo-6-(trifluoromethyl)cyclohex-3-en-1-oate is demonstrated. The compounds represent highly functionalized reactive intermediates for the synthesis of organic and heterocyclic compounds containing a trifluoromethyl group. 相似文献
8.
The olefins mentioned in the title were copolymerized with CO in the presence of palladium catalysts modified with dicyclohexyl{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl}phosphine. Productivities up to 95 g/(gPd · h) were achieved. The obtained copolymers were recovered in the pure, regio- und stereoregular polyketone structures 3 . The isotactic poly[2-benzyl-1-oxopropane-1,3-diyl] ( 3a ) and its analogues 3b , c were found to isomerize to the corresponding spirocyclic poly[3-(arylmethyl)tetrahydrofuran-2,2-5,5-tetrayl-2-oxy-2-methylene]s 4 in a suspension in CHC13, thus indicating that the spiroketal structure is thermodynamically the most stable for these copolymers. However, the atactic material did not undergo any structural transformation. These results show that regularity at the centers of chirality in the main chain is a prerequisite for the conversion of the polyketone to the spiroketal structure. 相似文献
9.
《Tetrahedron letters》1986,27(19):2139-2142
The title compounds of (1R*,3S*) configuration were prepared from 3-formyl-2,2-dimethyl-cyclopropanecarboxylate by addition of CF3CCl2ZnCl, acetylation, and reductive β-elimination with zinc, whereas the (1R*,3R*) isomer was derived from Me2C=CHCH(OH)CCl2CF3 by diazoacetylatlon. Cu(II) catalyzed intramolecular cyclization, and the zinc reduction. 相似文献
10.
11.
《Arabian Journal of Chemistry》2014,7(4):436-447
A series of 4-(1-aryl-5-chloro-2-oxo-1,2-dihydro-indol-3-ylideneamino)-N-substituted benzenesulfonamide derivatives (1–20) was synthesized and evaluated for its in vitro antimicrobial and anticancer activities. Antimicrobial results indicated that compounds N-(4-(1-benzoyl-5-chloro-2-oxoindolin-3-ylideneamino) phenylsulfonyl)-4-isopropoxy benzamide (9) and N-(4-(5-chloro-1-(2-chlorobenzoyl)-2-oxoindolin-3-ylideneamino) phenylsulfonyl)-4-isopropoxybenzamide (19) were found to be the most effective ones. The anticancer results indicated that almost all the synthesized compounds were more active than the standard drug carboplatin but less active than the standard drug 5-fluorouracil (5-FU) against both the cell lines (HCT116 and RAW 264.7). 4-(1-Benzoyl-5-chloro-2-oxoindolin-3-ylideneamino)-N-(pyrimidin-2-yl) benzenesulfonamide (3) was found to be most potent and exhibited selectivity toward HCT 116. QSAR studies indicated that antimicrobial activity of isatin derivatives against different microbial strains was governed by lipophilic parameter, log P and topological parameters valance zero and third order molecular connectivity indices (0χv and 3χv). 相似文献
12.
I. A. Strakova A. Ya. Strakov M. V. Petrova L. G. Delyatitskaya 《Chemistry of Heterocyclic Compounds》2000,36(4):459-464
Reaction of the potassium salt of 2-formyldimedone with hydrochlorides of 4-chloro-, 3-chloro-, 2-chloro-, 2,4-dichloro-, and 2,4-difluorophenylhydrazines gave the corresponding 2-arylhydrazinomethylene-dimedones which cyclized in acid media to 1-substituted 6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles. Oxidation of the latter with selenious acid gave the corresponding 4,5-dioxo-4,5,6,7-tetrahydroindazoles which were further converted into 3-aryl-5,5-dimethyl-4,5-dihydro-3H-pyrazolo[4,3-a]phenazines and 2,6-diaryl-4,4-dimethyl-4,5-dihydro-1H(3H)-indazolo[4,5-g]imidazoles.Riga Technical University, Riga LV-1658, Latvia; e-mail: marina@osi.lv. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 533–539, April, 2000. 相似文献
13.
Fifteen novel (3-chloro-5-(trifluoromethyl)pyridin-2-yloxy)phenyl containing Baylis-Hillman adduct derivatives were designed and synthesized. Evaluation of their biological activities showed that methyl 2-((3-(3-chloro-5-(trifluoromethyl)pyridin-2-yloxy)phenoxy)(phenyl)methyl)acrylate (2g) exhibited efficient broad-spectrum fungicidal activity, with 100% control of wheat powdery mildew and cucumber downy mildew and 98% control of cucumber anthracnose at 400 g ai/ha. Some of the other title compounds 2, 3 and two Baylis-Hillman bromide intermediates (11a, 11b) had moderate to good fungicidal activity. 相似文献
14.
Machhindra Gund S. Mohana Roopan Fazlur-Rahman Nawaz Khan Jong Sung Jin Rajesh Kumar A. Sudheer Kumar 《Research on Chemical Intermediates》2012,38(3-5):1111-1118
An efficient and regioselective O-alkylation of amides with a variety of electrophiles in the presence of silver nanoparticles is reported as part of our recent research on building blocks for synthesis of natural products. The nano-silver catalyst initiates O-alkylation of the amides by heteroalkyl halides. Reaction of equimolar 3-acetyl-6-chloro-4-phenylquinolin-2(1H)-one and 2-chloro-3-(chloromethyl)quinolines in the presence of silver nanoparticles in DMSO solution under reflux condition leads to the formation of 1-{1-[2-chloroquinolin-3-yl)methoxy]-6-chloro-4-phenylquinolin-3-yl}ethanones. 相似文献
15.
Conclusions 1-Tosyloxy-2,2-bis(trifluoromethyl)aziridine with NaCN in DMSO gives 2,2-bis(trifluoromethyl)-3-cyanoaziridine, which is apparently formed via the intermediate 2,2-bis(trifluoromethyl)-1-azirine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1187–1189, May, 1976 相似文献
16.
17.
K. Prabakaran F. Nawaz Khan Jong Sung Jin P. Manivel 《Research on Chemical Intermediates》2012,38(2):429-441
A series of pyrazole-4-carboxylates have been synthesised using indium bromide catalyst and the cyclisation of respective 3-substituted-isoquinolinylhydrazines 1 into their corresponding ethyl-2-(ethoxymethylene)-4,4,4-trifluoro-3-oxobutanoates 3 in ethanol solvent under ultrasonic irradiation at 90?°C for 30 min. The regio-selective cyclisation products were efficiently provided by indium bromide catalyst and are confirmed by nuclear Overhauser effect spectroscopy?Cnuclear magnetic resonance (NOESY?CNMR) studies. 相似文献
18.
Boris I. Usachev Dmitrii L. Obydennov Vyacheslav Ya. Sosnovskikh 《Tetrahedron letters》2009,50(31):4446-4448
6-(Trifluoromethyl)comanic acid reacts regioselectively with phenylhydrazine in water to give 5-[3,3,3-trifluoro-2-(phenylhydrazono)propyl]-1-phenyl-1H-pyrazole-3-carboxylic acid. Similar reaction in dioxane leads to 3-[3,3,3-trifluoro-2-(phenylhydrazono)propyl]-1-phenyl-1H-pyrazole-5-carboxylic acid. A strong solvent influence on the reaction route was also found for 6-(trifluoromethyl)comanic acid derivatives. 相似文献
19.
Capillary electrophoresis (CE) is a powerful technique to determine (2,3-epoxypropyl)trimethylammonium chloride, (3-chloro-2-hydroxypropyl)trimethylammonium chloride and their hydrolysis product (2,3-dihydroxypropyl)trimethylammonium chloride in complex matrices. The separation was performed in a 180 mM copper(II) sulphate-4 mM formic acid buffer at pH 3. The UV inactive target compounds were detected by indirect UV detection at 215 nm with a reference wavelength of 300 nm--copper(II) being the chromophor. The results were compared to data acquired by ion-pair HPLC with perchlorate as ion pair former in a 1 M aqueous sodium perchlorate solution in 0.2 mM phosphoric acid (pH 3.4) on a RP 18 column and refractive index detection as reference method. Results of both methods are in good agreement. 相似文献
20.
γ-Selective sulfenylation of the triethysilyloxypentadienyllithium 1 gave the versatile alkylthiodene 4 which on successive deprotonation and alkylation furnished with high regioselectivity the γ-products 6 . Fluoride-promoted silylether cleavage 6 → 7 may be followed by intramolecular [4 + 2]-addition 7c → 8 and sulfoxide elimination 8 → 9 . The conversions 7b → 12 and 7a → 17 demonstrate the feasibility of 5 to serve as an equivalent of the hypothetical β-deprotonated divinylketone 13 whose two enone units may be unmasked separately. 相似文献