Synthesis of acrylates based on tetracyclododecene and its methyl derivative

The reaction of catalytic and thermal addition of acrylic acid to tetracyclo[4.4.1^2,5.1^7,10.0^1,6]dodec-3-en and its 8-methyl-substituted derivative was studied. The reaction is intended for the synthesis of corresponding acrylates, which are reactive monomers suitable for producing high-molecular compounds.     

Stereochemistry of ketone olefination with methyl trimethylsilylacetate

High (Z)-stereoselectivity of olefination of methyl α-phenylthioalkyl and methyl α-phenylthioalkenyl ketones with methyl trimethylsilylacetate decreases in the case of ketones containing a higher alkyl-substituent in place of the methyl group. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1020–1021, April, 2005.     

Stereochemistry of seven-membered heterocycles 11. Isoenergy chair-twist conformation equilibrium in phthalylformal and its 2-phenyl derivative

Conclusions By means of dynamic¹³C NMR, spectra have been obtained for the frozen chair and twist conformers of phthalylformal and its 2-phenyl derivative. The -effects of the phenyl substituent have been analyzed for both conformational species. 2. The introduction of a phenyl group into position 2 of phthalylformal is not reflected in the magnitude of the conformational free energy.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1068–1071, May, 1983.     

Stereochemistry of a cubane-like photodimer of methyl 2-naphthoate

A novel type of C₂-symmetric-chiral ligand, based on a cubane-like photodimer 1 of methyl 2-naphthoate, is reported in this work. Crystal analysis reveals that the methyl carboxylate functionality is in an anti-head-to-head conformation and 1 is highly rigid. The optically pure enantiomers of 1 can be obtained simply by HPLC resolution.     

Gas chromatographic determination of thiabendazole in fruits as its methyl derivative.

Quantitative determination of thiabendazole, as its methyl derivative, has been achieved by gas-liquid chromatography with flame ionization detection and a column of 10% of DC-200 on Gas-Chrom Q at 240 degrees. Determination was possible with 10 to 200 ng per mul of the methylated reaction mixture. For determining thiabendazole in fruits, clean-up of the crude extracts by liquid-liquid partition allows satisfactory elimination of interference and permits determination in concentrations down to 0.1 ppm. The recovery of thiabendazole added to fruits at the 0.5-ppm level ranges from 90.3 to 94.9%. The methyl derivative was identified as N-methylthiabendazole by its elementary composition, by its melting-point, and by ultraviolet, infrared, mass and nuclear magnetic resonance spectroscopy.     

Emission profile of rapeseed methyl ester and its blend in a diesel engine

Fatty acid methyl esters, also known as biodiesel, have been shown to have a great deal of potential as petro-diesel substitutes. Biodiesel comprise a renewable alternative energy source, the development of which would clearly reduce global dependence on petroleum and would also help to reduce air pollution. This paper analyzes the fuel properties of rapeseed biodiesel and its blend with petro-diesel, as well as the emission profiles of a diesel engine on these fuels. Fuels performance studies were conducted in order to acquire comparative data regarding specific fuel consumption and exhaust emissions, including levels of carbon monoxide (CO), carbon dioxide (CO₂), smoke density, and NO_x, in an effort to assess the performance of these biodiesel and blend. The fuel consumption amount of oil operations at high loads was similar or greater than that observed during petro-diesel operation. The use of biodiesel is associated with lower smoke density than would be seen with petro-diesel. However, biodiesel and its blend increased the emission of CO, CO₂, and nitrogen oxides, to a greater degree than was seen with petro-diesel. The above results indicate that rapeseed biodiesel can be partially substituted for petro-diesel under most operating conditions, regarding both performance parameters and exhaust, without any modifications having to be made to the engine.     

Stereochemistry of alternating methacryloyl-L-valine methyl ester–maleic anhydride copolymer

The stereochemical composition of an alternating methacryloyl-L -valine methyl estermaleic anhydride (L-MAVM/MAn) copolymer which was prepared by the photocopolymerization of L-MAVM and MAn in dioxane at 25°C without initiator was investigated by proton magnetic resonance spectroscopy. The resonance of the ester methyl protons of the L-MAVM unit appeared as three split peaks at 3.65, 3.76, and 3.82 ppm, which could be assigned to those of the coisotactic (di-threo-tri-isotactic), coheterotactic and cosyndiotactic triads, respectively. The triad cotacticity determined according to these assignments indicated that the copolymer was composed predominantly of di-threo-tri-isotactic triad. Similarly PMR spectroscopic investigation of the acryloyl-L -valine methyl ester–maleic anhydride (L-AVM/MAn) copolymer with a 1:1 molar ratio of the monomers showed that the main tactic fraction of the copolymer was also di-threo-tri-isotactic one. Nevertheless, the circular dichroic investigation of the L-AVM/MAn copolymer before and after hydrolysis denied asymmetric induction into the polymer main chain. These results suggest that the propagation step in the photocopolymerization of L-MAVM or L-AVM with MAn proceeds by the trans-trans opening of the complexmer composed of a 1:1 molar ratio of L-MAVM or L-AVM and MAn.     

Reaction of methyl bromocycloalkanecarboxylates with zinc and dihydroisoquinoline derivative

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o-Bornylphenol: Stereochemistry and synthesis of new derivatives from its (+)-enantiomer

New derivatives of the (+)-enantiomer of o-bornylphenol were synthesized with a view to determine the configuration of chiral centers therein. The absolute configuration of the terpene substituents in the Mannich reaction product obtained from 4,13-diaza-18-crown-6 was estimated as (1R,2R,4S) on the basis of anomalous X-ray scattering.     

Stereochemistry of protected ornithine side chains of gramicidin S derivatives: X-ray crystal structure of the bis-Boc-tetra-N-methyl derivative of gramicidin S

An X-ray crystallographic analysis of the bis-Ndelta-Boc-tetra-Nalpha-methyl derivative of gramicidin S, cyclo(-Val-MeOrn(Boc)-Leu-d-MePhe-Pro-)2, was undertaken successfully (R-factor = 0.088). As expected, the main chain adopts an antiparallel pleated beta-sheet conformation, but the pleated sheet is slightly twisted, and the sense of twisting is opposite to that found in the reported crystal structures of the gramicidin S-urea complex and the bis-Ndelta-(trichloroacetyl) and bis-Ndelta-(m-bromobenzoyl) derivatives of gramicidin S. In agreement with the observed resistance toward N-methylation, the urethane NH groups of the protected Orn side chains are hydrogen bonded to the carbonyl groups of the d-Phe residues. However, the side-chain-main-chain hydrogen bonding is in the i --> i - 3 mode, although hydrogen bonding in the i --> i + 2 mode was deduced from a 1H NMR study of protected gramicidin S derivatives and was actually found in the crystal structures of the diacylated gramicidin S.     

Computational description of quantum chemical calculations and pharmacological studies of the synthesized chalcone derivative: A promising NLO material

The intended chalcone, (E)-1-(4-aminophenyl)-3-(4-ethoxyphenyl)-prop-2-en-1-one (4A3EP), was synthesized in an alkaline medium by the Claisen–Schmidt condensation reaction of 4-aminoacetophenone with 4-ethoxybenzaldehyde. Spectroscopic analytical techniques such as UV–visible, FT-IR, FT-RAMAN, ¹H NMR, and ¹³C NMR investigations were used to analyze the molecular structure of the title molecule. The optimized molecular structure of the chalcone in gas phase vibrational frequencies and associated vibrational assignments were theoretically studied and compared with experimental results using the B3LYP/6–311++G techniques. All the experimental results were found to be in line with the theoretical values. The non linear optical activity of the title compound was proved from the hyperpolarizability calculations. In addition, E_HOMO (?5.9038 eV), E_LUMO (?2.2833 eV), energy gap (3.6205 eV) and electrophilicity index (4.628) were calculated to explore the reactivity, stability and bio activity of the title compound. The molecular electrostatic potential map was generated in order to spot the electrophilic and nucleophilic sites in the title compound. Natural bond orbital analysis was investigated in order to forecast the stability and charge transfer tendency of a title molecule. FUKUI FUNCTIONS were also calculated using DFT. Its anti-inflammatory, anti-diabetic, and anti-oxidant activities were also investigated. A molecular docking model was used to study the ligand-protein binding interactions of a synthetic chalcone derivative with the main protease of SARS-CoV-2 (the PDB code is 6yb7).     

Stereochemistry of cyclic compounds Communication 63. Stereochemistry of the bromination of 4-methyl-cis-4-cyclohexene-1,2-dicarboxylic acid and its anhydride

Summary The stereochemistry of the bromination of 4-methyl-cis-4-cyclohexene-l,2-dicarboxylic acid (I) and its anhydride (II) was studied. The spatial structures of the products were proved, and a possible mechanism scheme for their formation was discussed.This article is published in accordance with a resolution of the Conference of Chief Editors of the Journals of the Academy of Sciences of the USSR, July 12, 1962, as a dissertation paper by A. L. Shabanov.     

Oxidation of benzyloxycarbonyl threonine and serine methyl esters to an oxamate derivative

Both benzyloxycarbonyl threonine and serine methyl esters, when subjected to oxidation with reagents based on chromium (VI) oxide, gave rise to the same $\text{N}$-protected methyl oxamate, whose structure was confirmed by an independent preparation.     

Stereochemistry of cyclic compounds Communication 64. Stereochemistry of the oxidation and bromination of 4,5-dimethyl-4-cyclohexene-cis-1,2-dicarboxylic acid and its anhydride

Conclusions A study was made of the oxidation and bromination of 4,5-dimethyl-4-cyclohexene-cis-1,2-dicarboxylic acid (I) and its anhydride (II), and proof is given for the configurations of the then formed-epoxy anhydride (III), 5-hydroxy and 5-bromo-lactone acids (IV) and (V), and cis-glycol (IX). On the basis of the results of the acid hydrolysis of the trans-dibromo anhydride (VI) it is suggested that the bromine atoms in this compound have a diaxial arrangement.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 689–695, April, 1966     

Synthesis of the trichloroacetamide derivative of enantio-iso-ADDA methyl ester

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.