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1.
Horia Petride Constantin Drãghici Cristina Florea Aurica Petride 《Central European Journal of Chemistry》2004,2(2):302-322
N-Benzylmorpholine,-piperidine, and-pyrrolidine (1A-C, resp.) are oxidised by RuO4 (generated in situ) at both endocyclic and exocyclic (benzylic) N—α-methylene positions to afford lactams (and dioxo-derivatives) and benzaldehyde (and benzoyl derivatives), respectively.
The N-oxides of 1A-C, formed by a minor side reaction, are not involved as intermediates. Control experiments showed the transient formation of
endo- and exocyclic iminium cations trapped with NaCN as the corresponding nitriles. The proposed course of the RuO4-mediated oxidation of 1A-C involves the consecutive steps 1⇒iminium cations+cyclic enamine⇒oxidation products. The endocyclic/exocyclic regioselectivity of the oxidation reaction lies
between 0.8 (for 1A) and 2.1 (for 1B). The amine cation radical and the N-α-C· carbon-centered radical seem not to be involved. 相似文献
2.
V. V. Kostrub E. B. Tsupak Yu. N. Tkachenko M. A. Shevchenko 《Russian Chemical Bulletin》2008,57(8):1754-1759
Reactions of 5-aryl- and 5,7-diaryl-1,3-dimethyl-2,4-dioxopyrano[4,3-d]pyrimidinium salts with hydrazine were studied. In the former case, the reaction products were the 6-amino-1,3-dimethyl-2,4-dioxopyrido[4,3-d]pyrimidinium salts. 5,7-Diarylpyrano[4,3-d]pyrimidinium salts were transformed into either the corresponding pyridinium salts or 1H-pyrimido-[5,4-d][1,2]diazepine-2,4(3H,9H)-diones, depending on the hydrazine concentration and the reaction time.
For Part 1, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1720–1725, May, 2008. 相似文献
3.
Vera L. M. Silva Artur M. S. Silva Diana C. G. A. Pinto José A. S. Cavaleiro Attila Vasas Tamás Patonay 《Monatshefte für Chemie / Chemical Monthly》2008,139(11):1307-1315
Several (E)- and (Z)-3-styrylchromones were prepared by two different methodologies, the Wittig reaction of chromone-3-carboxaldehyde with benzylic ylides and the Knoevenagel condensation of chromone-3-carboxaldehyde with phenylacetic acids in the presence of potassium tert-butoxide under microwave irradiation. The Knoevenagel reaction followed by a decarboxylation offered an efficient and diastereoselective method for preparing (E)-3-styrylchromones in a shorter reaction time. It was also demonstrated that phenylacetic acid can also be substituted with
success by phenylmalonic acid. The stereochemistry of all products was assigned by NMR experiments.
Correspondence: Artur M. S. Silva, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal. 相似文献
4.
J. A. Jilani 《Chemical Papers》2007,61(5):410-412
8-Amino-1-methoxy-6H-dibenzo[b,d]pyran-6-one was synthesized in a one-pot reaction of 2′,6′-dimethoxy-4-nitro-1,1′-biphenyl-2-carboxylic acid methyl ester
using hydroiodic acid as a reagent to effect O-demethylation, lactonization, and nitro reduction to amine. This new reaction represents an improved alternative to the previously
reported three-step reactions for this transformation. 相似文献
5.
Eleonora Marcucci Gianluca Martelli Mario Orena Samuele Rinaldi 《Monatshefte für Chemie / Chemical Monthly》2007,138(1):27-33
Summary. In the presence of DABCO, ethyl glyoxalate and (4S,5R)-1,5-dimethyl-3-acryloyl-4-phenylimidazolidin-2-one gave mixtures of the corresponding Baylis-Hillman adducts enriched in either isomer, depending on the absence or the presence of LiClO4 in the reaction mixture. A diastereomeric mixture in 10:90 dr allowed to definitively establish the mechanism of the reaction leading to trichloroacetamides starting from trichloroacetimidates
of the Baylis-Hillman adducts. 相似文献
6.
Svetlana Marković Igor Đurović Zoran Marković 《Monatshefte für Chemie / Chemical Monthly》2008,139(10):1169-1174
This work is an extension of our investigation of the mechanism of the Kolbe-Schmitt reaction of sodium 2-naphthoxide. The carboxylation reaction of sodium 2-naphthoxide in the position 6 is examined by means
of the B3LYP/LANL2DZ method. After the initial formation of sodium 2-naphthoxide-CO2 complex, the carbon of the CO2 moiety performs an electrophilic attack on the naphthalene ring in position 8. Further transformations lead to the formation
of sodium 6-hydroxy-2-naphthoate. Our findings are in good agreement with the experimental results on the carboxylation reaction
of sodium 2-naphthoxide.
Correspondence: Svetlana Marković, Faculty of Science, University of Kragujevac, 34000 Kragujevac, Serbia. 相似文献
7.
O. B. Ryabova M. I. Evstratova V. A. Makarov V. A. Tafeenko V. G. Granik 《Chemistry of Heterocyclic Compounds》2004,40(10):1352-1358
The reaction of 5-formyl-4-thiocyanatopyrimidines with nitromethane was studied under various conditions. The reaction was found unexpectedly to proceed with closure of a thiophene ring to give thieno[2,3-d]pyrimidines. The use of ammonium acetate as the catalyst leads to a side reaction involving closure of an isothiazole ring to give isothiazolo[5,4-d]pyrimidines. X-ray diffraction crystallographic analysis was used to confirm the structure of thieno[2,3-d]pyrimidine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1564–1571, October, 2004. 相似文献
8.
Different from organic solvent, self-assemblies are environment friendly media, and moreover, if they are used as micro-reactor,
many meaningful and exciting results may be obtained. In this paper, we investigated the photoisomerization of trans-stilbene in Triton X-100/n-C5H11OH/H2O microemulsions (a kind of self-assemblies) with different compositions and structures to establish the relationship between
the reaction yields and the compositions and structures of microemulsions. The results show that the yield of cis-stilbene is increased with the increase of water content or with the decrease of Triton X-100 content, and oil in water (O/W)
structure is the best structure for this reaction, which makes it possible to decrease the pollution of environment by organic
solvent always used in organic reactions. 相似文献
9.
Renata Ga<parová Daniel Zbojek Margita Lácová Katarína Král'ová Anton Gatial Branislav Horváth Alžbeta Krutošíková 《Central European Journal of Chemistry》2005,3(4):622-646
The reactions of substituted furo[3,2-b]pyrrole-5-carboxhydrazides 1 with 5-arylfuran-2-carboxaldehydes 2, 4,5-disubstituted furan-2-carboxaldehydes 3 and thiophene-2-carboxaldehyde 4 has been studied. The advantage of microwave irradiation on some of these reactions was reflected in the reduced reaction
time and increased yields. Reactions of 1 with 4-substituted 1,3-oxazol-5(4H)-ones 11 led to diacylhydrazines 13 or to imidazole derivatives 14 depending on the temperature. 1,2,4-Triazole-3-thione 17 was synthesized by two-step reaction of 1 with phenylisothiocyanate and subsequent base-catalyzed cyclization of thiosemicarbazide 16. The effects of hydrazones 5–10 on inhibition of photosynthetic electron transport in spinach chloroplasts and chlorophyll content in the antialgal suspensions
of Chlorella vulgaris were investigated. 相似文献
10.
Kioumars Aghapoor Farshid Mohsenzadeh Golriz Khanalizadeh Hossein R. Darabi 《Monatshefte für Chemie / Chemical Monthly》2007,138(1):61-65
Summary. Water has been found for the first time as a useful solvent in the Willgerodt-Kindler (WK) reaction for the synthesis of benzothiomorpholides in high yield at 80°C for 3 h. This novel approach confronts the WK protocol with a new situation in which water not only is not regarded as a serious disadvantage but also is applied in this
case as a useful solvent in the reaction. The basis of this finding is the presence of a methylene chain in the carbonyl substrates,
which leads to the high reaction selectivity of benzaldehydes over acetophenones. 相似文献
11.
L. M. Likhosherstov O. S. Novikova A. O. Zheltova V. N. Shibaev 《Russian Chemical Bulletin》2005,54(5):1294-1297
A series of nitrogen-containing physiologically active compounds underwent smooth N-monoalkylation with N-bromoacetyl-β-glycopyranosylamines derived from N-acetyl-D-glucosamine and lactose. This reaction was demonstrated to be promising for the introduction of carbohydrate residues into
heterocyclic compounds, viz., pyridine, imidazole, pyrimidinetrione, carboline, and piperazine derivatives, and into an amino acid, 5-hydroxy-L-tryptophan, which is unstable in alkaline media.
Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1256–1259, May, 2005. 相似文献
12.
A new synthetic approach to 4E,7Z-tridecadien-1-ylacetate, a component of the Phthorimaea opercucella (Zeller) potato moth sex pheromone, was developed using a highly stereoselective Claisen rearrangement and Wittig reaction.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 235–236, May–June, 2007. 相似文献
13.
Li-qin Cao Liu-ping Chen Ji-qing Jiao Shu-ying Zhang Wei Gao 《Colloid and polymer science》2007,285(11):1229-1236
Herein, we report a new method that has been developed to prepare thermoresponsive polymers. The white, dry, fine powders
were obtained directly from cross-linking polymerization of N-isopropylacrylamide in supercritical carbon dioxide (scCO2) with N,N-methylenebisacrylamide as a cross-linker. The effects of the reaction pressure and time as well as the initial concentrations
of the initiator, cross-linker, and monomer on the yield and morphology of the resulting polymer were investigated systematically.
The polymer yield was increased with the concentrations of the cross-linker, monomer, and reaction time. Under the condition
of using higher cross-linker concentrations, the cross-linked poly (N-isopropylacrylamide) microparticles with diameters of 50 nm were generated in scCO2 in high-yield and short reaction times. These results suggest that the synthetic method using scCO2 can be used to prepare biomedical materials such as the controlled drug-release system. 相似文献
14.
V. A. Dodonov Yu. L. Kuznetsova M. A. Lopatin A. A. Skatova 《Russian Chemical Bulletin》2004,53(10):2209-2214
The polymerization of methyl methacrylate initiated by dicyclohexyl peroxydicarbonate at 30 °C was studied in the presence of tri-n-butylboron and a series of quinones, namely, p-benzoquinone, chloranil, and 2,5-di-tert-butyl-p-benzoquinone, whose concentration changed from 0.25 to 2.00 mol.%. The initial polymerization rate and molecular weight of poly(methyl methacrylate) depend on the structure and concentration of quinone. The growth radicals react with p-benzoquinone and chloranil predominantly at the C=C bond, while they react at the C=O bond of 2,5-di-tert-butyl-p-benzoquinone. The terminal stable oxygen-centered radicals that formed react with alkylborane, terminating reaction chains and generating alkyl radicals into the bulk. The latter are involved in chain initiation.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2114–2119, October, 2004. 相似文献
15.
Summary. Imidazo[1,2-a]azine derivatives are synthesized by a one-pot three-component reaction of an 2-aminoazine, an aldehyde, and trimethylsilylcyanide
in the presence of 1-n-butyl-3-methylimidazolium bromide as a recoverable ionic liquid, in moderate to excellent yields with relatively short reaction
times. 相似文献
16.
A. V. Piskunov A. V. Lado G. A. Abakumov V. K. Cherkasov O. V. Kuznetsova G. K. Fukin E. V. Baranov 《Russian Chemical Bulletin》2007,56(1):97-103
Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL2 (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions
in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ2MgLn (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et2O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy2]2 and SQ2Mg·DME complexes were established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007. 相似文献
17.
Solvent-controlled chemoselective palladium-catalyzed oligomerization of tert-butyl acetylene is reported in this paper. The reaction was carried out smoothly in benzene/n-BuOH binary solvent system. When unpolar aprotic benzene was the preponderating component in the binary system, a cyclotrimerization
process occurred to produce 1,3,5-tri-tert-butylbenzene via a mechanism of three acetylene molecules, inserted step by step, forming σ-butadienyl-Pd and σ-hexatrienyl-Pd intermediates. While when the polar, protic and strong coordinating component n-BuOH, which aids Cu(II) to cleave the C-Pd σ-bonds and solvate Pd(II), Cu(II) cations, halo anion, σ-butadienyl-Pd intermediate, etc., was increased to a certain extent in the binary solvent system, the reaction proceeded
readily via a n-BuOH-promoted mechanism to give (3Z,5Z)-2,2,7,7-tetramethyl-3,6-dichloro-3,5-octadiene or (3Z,5Z)-2,2,7,7-tetramethyl-3,6-dibromo-3,5-octadiene, respectively. Possible weak hydrogen bonds and n-π weak force between n-BuOH (electron pair donor (EPD)) and tert-butyl acetylene (and σ-butadienyl-Pd intermediate, electron pair acceptor (EPA)) in the latter process were also in favor of the n-BuOH promoted pathway. Meanwhile, the coupling product 2,2,7,7-tetramethyl-3,5-octadiyne was exclusively obtained when the
reaction was conducted in singular polar H2O. Influences of the solvent, catalysts, as well as possible mechanism were discussed in this paper. 相似文献
18.
Claudia Mureşanu Lucian Copolovici Florina Pogącean 《Central European Journal of Chemistry》2005,3(4):592-604
The inhibitory effect of para-nitrophenol on the catalytic reaction of catalase was investigated. Michaelis-Menten kinetic parameters were determined from
Lineweaver-Burk plots obtained in the absence or in the presence of the inhibitor. The inhibitor pattern, revealed by the
Lineweaver-Burk plots, suggested a fully mixed inhibition mechanism. Spectrophotometric monitoring of the indicator reaction:
in conjunction with initial rate measurements was employed for the kinetic determination of the inhibitor. Calibration plots
of initial rate vs. para-nitrophenol concentration were linear in the concentration range 0.9·10−5–2.5·10−5 mol/L and the detection limit was 3·10−6 mol/L (417 μg/L) para-nitrophenol. Interferences from other phenolic compounds like orto-cresole, meta-and orto-nitrophenol were observed. 相似文献
19.
T. G. Deryabina M. A. Demina N. P. Belskaya V. A. Bakulev 《Russian Chemical Bulletin》2005,54(12):2880-2889
The reaction of cyanothioacrylamides with dimethyl acetylenedicarboxylate, methyl propiolate, and N-phenylmaleimide was studied. The reaction follows a cycloaddition pathway to give thiopyrans, irrespective of the electronic
or spatial effects of the substituents in the thioamide group and in position 3 of the 1-thiabuta-1,3-diene system. The reaction
is regio-and stereoselective.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2784–2792, December, 2005. 相似文献
20.
N. E. Golantsov A. V. Karchava V. M. Nosova M. A. Yurovskaya 《Russian Chemical Bulletin》2005,54(1):226-230
4-Substituted 1,2,3,4-tetrahydropyrazino[1,2-a]indoles were synthesized from 2-cyanoindole. (R)-4-Methyl-1,2,3,4-tetrahydropyrazino[1,2-a]indole was obtained by the Mitsunobu reaction. Stereoselective reduction of 4-substituted 1,2,3,4-tetrahydropyrazino[1,2-a]indoles gave 4-substituted 1,2,3,4,10,10a-hexahydropyrazino[1,2-a]indoles. (4R, 10aR)-4-Methyl-1,2,3,4,10,10a-hexahydropyrazino[1,2-a]indole was synthesized.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 221–225, January, 2005. 相似文献