共查询到20条相似文献,搜索用时 31 毫秒
1.
A. B. Terent'ev T. T. Vasil'eva N. A. Kuz'mina E. I. Mysov N. S. Ikonnikov N. Yu. Kuznetsov Yu. N. Belokon 《Russian Chemical Bulletin》1999,48(6):1121-1127
Reformatsky-type addition of esters of α-halogeno carboxylic acids to aldehydes and ketones in the presence of Fe(CO)5 and an activating agent (CBrCl3 or I2) afforded the corresponding esters of β-hydroxy acids in good yields. Possible reaction mechanisms are discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1132–1138, June, 1999. 相似文献
2.
M. N. Elinson S. K. Fedukovich Z. A. Starikova A. N. Vereshchagin P. A. Belyakov S. V. Gorbunov G. I. Nikishin 《Russian Chemical Bulletin》2006,55(1):106-111
Electrolysis of 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylic acid esters in alcohols in an undivided cell in the
presence of NaBr or NaOAc afforded 6-substituted (1R,5R, 6R)*-4,4-dialkoxy-5-cyano-2-oxo-3-azabicyclo[3.1.0]hexane-1-carboxylic acid esters in 80–95% yields.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 102–107, January, 2006. 相似文献
3.
F. I. Guseinov 《Russian Chemical Bulletin》1998,47(4):663-665
α,α-Dichloro-β-oxoaldehyde diethyl acetals decompose under the action of bases (NaOH, MeONa) with cleavage of the carbon-carbon
bond and formation of carboxylic acids or their esters and the dichloroacetaldehyde diethyl acetal carbanion. The latter reactsin situ with benzaldehyde to form stable α-chloro-α,β-epoxyacetal. α-Chloro-α-formyl-γ-butyrolactone diethyl acetal is transformed
into α-chloro-α-diethoxymethyl-γ-hydroxybutyric acid under the action of an alkali.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 685–687, April, 1998. 相似文献
4.
Alexander O. Terent’ev Maxim M. Platonov Alexander V. Kutkin 《Central European Journal of Chemistry》2006,4(2):207-215
A new oxidation process has been found where α,ω-dicarboxylic acid esters and ω-hydroxycarboxylic acid esters are formed on heating gem-bishydroperoxides in alcohol in the presence of BF3·Et2O. By addition of H2O2 to this reaction α,ω-dicarboxylic acid esters are formed almost selectively. 相似文献
5.
Débora de Oliveira Irajá do Nascimento Filho Marco di Luccio Carina Faccio Clarissa Dalla Rosa João Paulo Bender Nádia Lipke Cristiana Amroginski Cláudio Dariva José Vladimir de Oliveira 《Applied biochemistry and biotechnology》2005,121(1-3):231-241
This work investigated the production of fatty acid ethyl esters (FAEEs) from soybean oil using n-hexane as solvent and two commercial lipases as catalysts, Novozym 435 and Lipozyme IM. A Taguchi experimental design was
adopted considering the variables temperature (35–65°C), addition of water (0–10 wt/wt%), enzyme (5–20 wt/wt%) concentration,
and oil-to-ethanol molar ratio (1:3–1:10). It is shown that complete conversion in FAEE is achieved for some experimental
conditions. The effects of process variables on reaction conversion and kinetics of the enzymatic reactions are presented
for all experimental conditions investigated in the factorial design. 相似文献
6.
Waldemar Adam Chantu R. Saha-Möller Oliver Weichold 《Monatshefte für Chemie / Chemical Monthly》2000,131(6):697-705
Summary. Optically active diastereomeric β-hydroperoxy esters 4 have been prepared by singlet oxygen ene reaction of β,γ-unsaturated esters 3 and subsequent horseradish peroxidase (HRP) catalyzed kinetic resolution of the ene product. The highest enantiomeric excess
(up to 95%) has been obtained for the isopropyl ester threo-4c, which establishes that the size of the remote ester functionality exercises appreciable control in the enantioselectivity
of the enzymatic kinetic resolution.
Received December 20, 1999. Accepted (revised) February 11, 2000 相似文献
7.
When boiled in aromatic hydrocarbons, solutions of α-nitro-α-azinylcyanoacetic esters of the pyrimidine, pyrazine, ands-triazine series gave the corresponding α-hydroxy derivatives of α-azinylcyanoacetic esters in high yields.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1407–1409, July, 1997. 相似文献
8.
E. D. Matveeva T. A. Podrugina M. V. Prisyazhnoi I. N. Rusetskaya N. S. Zefirov 《Russian Chemical Bulletin》2007,56(4):798-805
Interaction of aliphatic and aromatic aldehydes and ketones with optically active L-α-amino acids or their esters in the three-component catalytic one-pot synthesis of α-aminophosphonates was studied. The
corresponding α-amino phosphonates are formed in high yields as mixtures of diastereomers.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 768–774, April, 2007. 相似文献
9.
V. A. Mamedov E. A. Berdnikov S. Tsuboi H. Hamamoto T. Komiyama E. A. Gorbunova A. T. Gubaidullin I. A. Litvinov 《Russian Chemical Bulletin》2006,55(8):1455-1463
The Darzens reaction of dihaloacetic acid esters with aromatic aldehydes produces either arylhaloglycidic or arylhalopyruvic
esters depending on the nature of the substituent in the aromatic ring. Alkyl p-methoxyphenylchloropyruvates undergo spontaneous intermolecular cyclocondensation to form pyranone or furanone derivatives
depending on the character of the alkyl fragment.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1402–1410, August, 2006. 相似文献
10.
Roman Mazurkiewicz Mirosława Grymel 《Monatshefte für Chemie / Chemical Monthly》2002,133(9):1197-1204
Summary. Reactions of N-acyl-α-triphenylphosphonio-α-amino acid methyl esters with organic bases (triethylamine or DBU) were investigated as the crucial step of the base-catalyzed displacement of the triphenylphosphonium group by nucleophiles.
It was proved that N-acyl-α-triphenylphosphonioglycinates are transformed to an equilibrium mixture of the corresponding N-acyliminoacetates and N-acyl-α-triphenylphosphoranylidene glycinates by bases. In the case of N-acyl-α-triphenylphosphonio-α-amino acid esters with quaternary α-carbon, the α-substituted homologues of the N-acyliminoacetates were detected to be the only primary reaction product which, however, can undergo further tautomerization
to the corresponding α,β-dehydro-α-amino acid derivatives. In both these cases the reaction of N-acyl-α-triphenylphosphonio-α-amino acid esters with nucleophiles proceeds via the addition of a nucleophile to the activated C=N double bond of the N-acylimino intermediate.
Corresponding author. E-mail: romanm@zeus.polsl.gliwice.pl
Received October 31, 2001. Accepted (revised) December 17, 2001 相似文献
11.
Débora de Oliveira Marco Di Luccio Carina Faccio Clarissa Dalla Rosa João Paulo Bender Nádia Lipke Silvana Menoncin Cristiana Amroginski José Vladimir de Oliveira 《Applied biochemistry and biotechnology》2004,115(1-3):771-780
We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent and two commercial lipases, Novozym 435 and Lipozyme IM, as catalysts. For this purpose, a Taguchi experimental
design was adopted considering the following variables: temperature (35–65°C), water (0–10 wt/wt%), and enzyme (5–20 wt/wt%)
concentrations and oil-to-ethanol molar ratio (1∶3 to 1∶10). An empirical model was then built so as to assess the main and
cross-variable effects on the reaction conversion and also to maximize biodiesel production for each enzyme. For the system
containing Novozym 435 as tatalyst the maximum conversion obtained was 81.4% at 65°C, enzyme concentration of 20 wt/wt%, water
concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶10. When the catalyst was Lipozyme IM, a conversion as high
as 98% was obtained at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar
ratio of 1∶3. 相似文献
12.
S. G. Zlotin G. V. Kryshtal G. M. Zhdankina A. V. Bogolyubov S. G. Postikova V. A. Tartakovsky 《Russian Chemical Bulletin》2007,56(8):1487-1494
An expedient method for the synthesis of α-nitro-δ-oxocarboxylic and α-nitroglutaric acid esters, including ones with isoprenoid
substituents, by the solvent-free reaction of the corresponding alkyl α-nitrocarboxylates with activated olefins, assisted
by heterogeneous catalytic system KHCO3—1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), was elaborated. The product yields remain stable even after eight recycles of the catalytic system. The synthesized dimethyl
2-(poly)prenyl-2-nitropentanedioates upon treatment with Fe in AcOH were reduced to 2-(poly)prenyl-5-oxopyrrolidine-2-carboxylates.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1431–1438, August, 2007. 相似文献
13.
M. V. Mavrov L. D. Konyushkin N. I. Simirskaya S. G. Zlotin 《Russian Chemical Bulletin》2005,54(12):2857-2866
Previously unknown 4-amino derivatives of spiro-annelated Δ2-butenolide were synthesized by the addition of various amines at the activated triple bond of 4-hydroxy-2-alkynoic esters.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2761–2770, December, 2005. 相似文献
14.
L. A. Baltina Jr. R. M. Kondratenko L. A. Baltina O. A. Plyasunova F. Z. Galin G. A. Tolstikov 《Chemistry of Natural Compounds》2006,42(5):543-548
Activated esters and N-hydroxybenzotriazole-N,N′-dicyclohexylcarbodiimide (DCC) or N-hydroxysuccinimide-DCC were used to synthesize conjugates of glycyrrhizic acid (GA) with Nɛ-carbobenzyloxy-L-lysine [Lys(Z)-OH] and its esters containing two or three amino components. It was shown that the conjugate of GA 30-methyl ester with
Lys(Z)-OH possessed anti-HIV-1 activity.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 437–441, September–October, 2006. 相似文献
15.
1-Hydroxy-2-oxo-3-phenyl-1,2-dihydroquinoxaline 4-oxide under conditions of the Mitsunobu reaction reacts with alcohols giving
the corresponding esters at the hydroxy group in position 1. Other representatives of hydroxamic acids such as 1,4-dihydroxyperhydroquinoxaline-2,3-dione
and 1,4-dihydroxy-3,3,6,6-tetramethylpiperazine-2,5-dione undergo destruction under these conditions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1240–1243, June, 2008. 相似文献
16.
Waldemar Adam Chantu R. Saha-M?ller Oliver Weichold 《Monatshefte für Chemie / Chemical Monthly》2000,13(7):697-705
Optically active diastereomeric β-hydroperoxy esters 4 have been prepared by singlet oxygen ene reaction of β,γ-unsaturated esters 3 and subsequent horseradish peroxidase (HRP) catalyzed kinetic resolution of the ene product. The highest enantiomeric excess (up to 95%) has been obtained for the isopropyl ester threo-4c, which establishes that the size of the remote ester functionality exercises appreciable control in the enantioselectivity of the enzymatic kinetic resolution. 相似文献
17.
In this study, stoichiometric protonation constants of L-tyrosine, L-cysteine, L-tryptophane, L-lysine, and L-histidine, and
their methyl and ethyl esters in water and ethanol–water mixtures of 30, 50, and 70% ethanol (v/v), were determined potentiometrically
using a combined pH electrode system calibrated as the concentration of hydrogen ion. Titrations were performed at 25∘C and the ionic strength of the medium was maintained at 0.10 mol⋅L−1 using sodium chloride. Protonation constants were calculated by using the BEST computer program. The effect of solvent composition
on the protonation constants is discussed. The log10 K2 values of esters generally decreased with increasing ethanol content. However, the log10 K1 values of the esters of L-tyrosine, L-cysteine, and L-tryptophane were found to increase with increasing ethanol content
in contrast those of L-lysine and L-histidine esters. 相似文献
18.
This work presents the use of sulfated tin oxide enhanced with SiO2 (SO42−/SnO2-SiO2) as a superacid solid catalyst to produce methyl esters from Jatropha curcas oil. The study was conducted using the design of experiment (DoE), specifically a response surface methodology based on a
threevariable central composite design (CCD) with α = 2. The reaction parameters in the parametric study were: reaction temperature (60°C to 180°C), reaction period (1 h to
3 h), and methanol to oil mole ratio (1: 6 to 1: 24). Production of the esters was conducted using an autoclave nitrogen pressurized
reactor equipped with a thermocouple and a magnetic stirrer. The maximum methyl esters yield of 97 mass % was obtained at
the reaction conditions: temperature of 180°C, reaction period of 2 h, and methanol to oil mole ratio of 1: 15. The catalyst
amount and agitation speed were fixed to 3 mass % and 350–360 min−1, respectively. Properties of the methyl esters obtained fell within the recommended biodiesel standards such as ASTM D6751
(ASTM, 2003). 相似文献
19.
Okadaic acid (OA) and dinophysistoxins-1 and -2 (DTX1, DTX2), the toxins responsible for incidents of diarrhetic shellfish
poisoning (DSP), can occur as complex mixtures of ester derivatives in both plankton and shellfish. Alkaline hydrolysis is
usually employed to release parent OA/DTX toxins, and analyses are conducted before and after hydrolysis to determine the
concentrations of nonesterified and esterified toxins. Recent research has shown that other toxins, including pectenotoxins
and spirolides, can also exist as esters in shellfish, but these toxins cannot survive alkaline hydrolysis. A promising alternative
approach is enzymatic hydrolysis. In this study, two enzymatic methods were developed for the hydrolysis of 7-O-acyl esters, “DTX3,” and the carboxylate esters of OA, “diol-esters.” Porcine pancreatic lipase induced complete conversion
of DTX3 to OA and DTXs within one hour for reference solutions. The presence of mussel tissue matrix reduced the rate of hydrolysis,
but an optimized lipase concentration resulted in greater than 95% conversion within four hours. OA-diol-ester was hydrolyzed
by porcine liver esterase and was completely converted to OA in less than 30 min, even in the presence of mussel tissue matrix.
Esters and OA/DTX toxins were all monitored by LC–MS. Further experiments with pectenotoxin esters indicated that enzymatic
hydrolysis could also be applied to esters of other toxins. Enzymatic hydrolysis has excellent potential as an alternative
to the conventional alkaline hydrolysis procedure used in the preparation of shellfish samples for the analysis of toxins. 相似文献
20.
M. S. Frasinyuk S. P. Bondarenko O. V. Shablykina V. P. Khilya 《Chemistry of Heterocyclic Compounds》2011,47(9):1155-1163
The formylation of esters of 5-hydroxy-1-benzofuran-3-carboxylic acid has been studied. The interaction of the synthesized
aldehydes with esters of β-keto acids and hetarylacetonitriles gave furo[3,2-f]coumarin-1-carboxylic acids derivatives. 相似文献