Addition of thiols at the double bond of methyl esters of 1-alkylcyclopropene-3-carboxylic acids

This is the first report of the addition of propyl and phenyl mercaptans at the double bond in the methyl ester of 1-methylcyclopropene-3-carboxylic acid with the formation of esters of thio-substituted cyclopropanecarboxylic acids in 67–72% yield. The addition of the thio group proceeds selectively at the least substituted atom of the double bond in the position anti to the methoxycarbonyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 220–222, January, 1991.     

Dextran derivatives

Conclusions 1. Acid chloride and carbodiimide methods for the synthesis of N-aminoacyl derivatives of carboxymethyldextran have been developed.2. Using these methods, derivatives of carboxymethyldextran containing residues of glycine esters (with different degrees of substitution) and residues of the methyl ester of L-histidine have been synthesized.3. A method for obtaining carboxymethyldextrans with different degrees of substitution has been developed.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 6, pp. 525–531, 1969     

Reactions of aromatic and heteroaromatic compounds carrying electron-acceptor substituents. 26. Acylaminomethylation of 2-acylthiophenes, 2-thiophenecarboxylic acid,and its esters

The reaction of 2-thiophene aldehyde, 2-acetylthiophene, 2-thiophene carboxylic acid, and its methyl ester with N-(hydroxymethyl)chloroacetamide in concentrated sulfuric acid yields a mixture of 4- and 5-(N-chloroacetylamino) methyl derivatives, the former being preferred.For Communication 25, see [1].Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 793–797, June, 1986.     

Oxidation of l-methionine with aqueous chromic acid: a kinetic study

The kinetics of oxidation of l-methionine by chromic acid in acidic medium (pH=0.83–2.2) has been studied spectrophotometrically. The effect of l-methionine and chromium(VI) concentrations on the rate of the reaction was determined. The reaction rate decreases with increasing the pH of the medium. The kinetics of the formation of a chromium(III) complex conform to the rate law:with k1=7.5×10–2s–1 and Kes1=43.85 at constant [H+]=1.9×10–2moldm–3 and [l-methionine]T= 2.0×10–2moldm–3. The same values were found with [l-methionine]T variation at constant [H+]. The reaction proceeds through formation of chromium(VI)-l-methionine ester in a rapid pre-equilibrium step, followed by a slower redox reaction of the ester. The present study provides kinetic evidence for formation of a complex ion (ester). One mole of Cr2O72– oxidizes four moles of l-methionine, which acts as a monodentate ligand and binds to chromium(VI) through the sulfur atom. The coordinated sulfur atom of l-methionine–chromium(VI) ester is responsible for the oxidative degradation (breaking of the C1-C2 bond) of l-methionine. Coordinated oxygen of the carboxylate group inhibits the cleavage of the C1-C2 bond.     

The esterase and peptidase activities of an elastolytic enzyme of Actinomyces rimosus

Summary 1. It has been shown that the values of K_m for the esterase activity of elastase ofActinomyces rimosus and for pancreatic elastase are of the same order of magnitude.2. The elastase ofActinomyces rimosus, unlike the pancreatic enzyme, is capable of hydrolyzing only the methyl ester of N-acetyltrialanine, and not the mono and di derivatives.3. It has been found that in the initial stage of the hydrolysis reaction it is mainly the ester bonds that are cleaved.Institute of Molecular Biology, Academy of Sciences of the USSR, Moscow. N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 693–695, September–October, 1977.     

Synthesis of aminoacyl derivatives of nucleosides,nucleotides, and polynucleotides

Conclusions The possibility has been shown of extending the method of synthesis of O-aminoacyl derivatives of nucleotides and nucleoside triphosphates to prepare 3(2)-O-peptidyI-micleoside-5-triphosphates.TranslatedfromlzvestiyaAkademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1369–1372, June, 1970.     

Investigations in the fie ld of substituted furanurona ldehydes steric directivity of the nitromethane condensation

Summary 1. The condensation of the anomeric methyl 2,3-di-O-benzyl-D-xylofuranosiduronaldehydes with nitromethane has been studied.2. It has been shown that the position of the substituent at the glycosidic center has an influence on the steric directivity of this reaction.3. The structure of the 6-nitro-6-deoxyhexofuranosides synthesized has been confirmed by their conversion into known derivatives of methyl D-glucofuranosides.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 8–12, January–February, 1972.     

Composition of the neutral lipids of Chlorella vulgaris

Summary The qualitative and quantitative compositions of the neutral lipids and the fatty-acid composition of the individual classes of neutral lipids isolated from fresh, freeze-dried, and air-dry cells of the algaChlorella vulgaris have been investigated.The presence of natural fatty acid methyl esters in the lipid extract of the fresh and air-dry chlorella cells has been established.It has been shown that the fatty acid methyl ester fraction is enriched with palmitic acid as compared with the triglyceride and free fatty acid fractions.The main unsaturated acids of the chlorella lipids contain the first double bond in the ⁹ position.Division of Microbiology of the Academy of Sciences of the Uzbek SSR, Tashkent. Institute of the Chemistry of Plant Substances, Academy of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 49–53, January–February, 1978.     

Glycosylation of cardenolides. VI. Periplogenin mono- and diglucosiduronic acids

Summary The Koenigs-Knorr condensation of the acetobromo derivative of methyl glucuronate with periplogenin has given the methyl ester of periplogenin monoglucosiduronic acid and the dimethyl ester of periplogenin 3,5-diglucosiduronic acid.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 72–77, January–February, 1977.     

Synthesis of 30-amino derivatives of 3,28-di-O-acetylbetulin

30-Amino derivatives of the lupane group were prepared by reaction of 3,28-di-O-acetyl-30-bromolup- 20(29)-ene with L-valine methyl ester and aliphatic amines.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 469–471, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Conversions of 2-thioxo-1,3-dithiol-4,5-dicarboxylic acid dimethyl ester — The path to a new heterocyclic system, (4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2,5,7-trione and 5,6-dimercaptouracil derivatives

The conversions of 2-thioxo-1,3-dithiol-4,5-dicarboxylic acid methyl ester into anhydride, mono- and diamide, and monoamide methyl ester were demonstrated. The new heterocyclic system, (4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2,5,7-trione, was obtained by oxidative rearrangement-cyclization of 2-oxo-1,3-dithiol-4,5-dicarboxylic acid diamide with phenyliodosyl(hydroxy)tosylate and used to synthesize previously unknown 5,6-dimercaptouracil derivatives, including nickel dithiolene complex.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1270–1275, September, 1992.     

Reaction of diazoacetone,methyl diazoacetate,and dimethyl diazomalonate with 2-ethoxycarbonyl and 2-cyanofurans in the presence of rhodium acetate

Conclusions The reaction of 2-ethoxycarbonylfuran with diazoacetone and methyl diazoacetate in the presence of rhodium acetate at 20°C gives bicyclic adducts of the corresponding carbenes at a furan ring double bond in 18–22% yield with the complete absence of products of opening of the furan ring (acyclic oxodienes). In analogous reactions, 2-cyanofuran gives derivatives of 5-(2-furyl)oxazoles in yields up to 55%, which are the products of the 1,3-dipolar cyclo-addition of the carbenes at the cyano group in addition to the bicyclic adducts in 12–17% yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2833–2836, December, 1988.     

Asymmetric synthesis of amino acids via the catalytic reduction of acylaminoacrylic acid azlactone derivatives

Reductive aminolysis of 2-methyl-4-benzylidene-²-oxazolin-5-one upon treatment with a PdCl₂-S-phenylalanine ester (dimethylamide) catalytic system leads to the formation of the corresponding acylated dipeptide derivatives, with the R,S-configuration (diastereomer) predominating (DE 9–27%). The reaction stereoselectivity in dimethoxyethane increases sharply in the presence of triethylamine additive, and in the case of S-phenylalanine methyl ester reaches 47%. The stepwise mechanism for this process has been studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 811–818, April, 1990.     

Synthesis of a hexapeptide containing valine, leucine, and glutamic acid

Summary The previously unreported methyl ester of N-benzyloxycarbonyl-L-phenylalanyl-L-valyl-O-methyl-L-glutamyl-L-leucyl-L-valyl-L-alanine has been synthesized.T. G. Shevchenko Kiev State University. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 785–788, November–December, 1975.     

Thermodynamics of Amino Acid Methyl Ester Hydrochlorides—Crown Ether Complexes in Methanol at 25°C

Stability constants, free energies, and enthalpies and entropies of the complexation of L-alanine methyl ester hydrochloride (L-Ala-HCl), L-phenylalanine methyl ester hydrochloride (L-Phe-HCl), and valine methyl ester hydrochloride (L-Val-HCl) with 15-crown-5 (15C5), benzo-15-crown-5 (B15C5), 18-crown-6 (18C6), benzo-18-crown-6 (B18C6), dicyclohexano-18-crown-6 (DC18C6), and dicyclohexano-24-crown-8 (DC24C8) in methanol are reported for 20°C. No significant variation in the stability constants and free energies of complexation is observed, indicating that the various crown ethers are poorly selective in binding the amino acids. However, the nature of the crown ether and the amino acid and their pattern of substitution cause a remarkable variation in the enthalpies and entropies of complexation. This indicates a strong enthalpy–entropy compensation effect. The enthalpy–entropy compensation effect for the crown ether complexes of the amino acid methyl ester hydrochlorides reported herein is compared with that of the crown ethers complexes of the amino alcohols and the free amino acid. It is found that the enthalpy–entropy compensation effect holds equally for the three classes of complexes.     

Synthesis and structure of aziridine-2-carboxylic acid derivatives with asymmetric substituents attached to the nitrogen atom

The synthesis, investigation of the structure, separation, and x-ray diffraction analysis of diastereomeric aziridine-2-carboxylic acid derivatives obtained from 2,3-dibromopropionic acid methyl ester or amide and methyl esters of amino acids are described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1495–1500, November, 1982.     

Stereochemical studies, 88. Saturated heterocycles, 83: Synthesis of stereoisomeric condensed-skeleton 2-imino-substituted 1,3-oxazines

Thiourea ( - , - ) and urea ( - , - ) derivatives have been prepared from - and -2-aminomethyl-1-cyclopentanols, and -l-cyclohexanols and their -methyl derivatives with phenyl isothiocyanate and phenyl isocyanate, respectively. Treatment of and with methyl iodide and then with alkali furnished - with the exception of the - -methyl derivative - 2-phenylimino-1,3-oxazines ( , , - ). The remarkable fact that the ring closure of -2-amino-methyl-1-cyclopentanols gives 1,3-heterocycles with -anellation supports the assumption that the -1,2-disubstituted-1,3-difunctional cyclopentanes undergo ring closure when 1,3-heterocycles with a delocalized pπ bond system are formed. With thionyl chloride the -urea derivatives - afforded an elimination product ( ), whereas the isomers yielded the oxazines by inversion. ¹H and ¹³C NMR spectroscopic studies indicated that in - , the “O-in” conformers are favoured (the methylene group of the hetero ring is , while the oxygen atom is ) and all 3-unsubstituted-2-phenylimino-1,3-oxazines exist exclusively in the tautomeric form with an C=N bond.     

Molecular structure and conformational analysis of chirai (−)-3-(4-bromobenzylidene)-1-isopropyl-2-methoxy-4-methylcyclohexene

(–)-3-(4-Bromobenzylidene)-1-isopropyl-2-methoxy-4-methylcyclohexene, capable of inducing spiral supramolecular ordering when introduced to nematic and some smectic mesophases, has been studied by an X-ray structural analysis. The crystals are orthorhombic; at 20 °Ca = 6.055(1),b = 13.282(3),c=20.734(4) Å,V=1668(1) ų,d _calc = 1.380 g cm^–3, space groupP2 ₁2₁2₁ Z=4. The cyclohexene ring has a conformation intermediate between a sofa and a half-chair. The methyl and methoxyl groups are in asyn orientation with respect to the mean plane of the cycle. The angle between the plane of the aryl substituent and the exocyclic double bond is 33°. The observed distortions of bond angles at unsaturated carbon atoms are typical of derivatives of benzylidenecyclohexene. Molecular mechanics calculations demonstrated that the conformation observed in the crystalline state is not the most favorable, and this conformation is stabilized through intermolecular interactions upon stacking in crystals. It was shown that the relative orientation of the methyl and methoxyl groups as well as the orientation of the aryl substituent substantially affect the conformation of the cyclohexene ring.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2437–2442, December, 1995.     

Investigations in the field of complex lipids

Summary 1. The methyl ester of N-(N-carbobenzoyglycyl)-methoxyneuraminic acid has been synthesized by the carbodiimide method.2. Hydrogenation of the methyl ester of N-(N-carbobenzoxyglycyl)-methoxyneuraminic acid over Pb/BaSO₄ has given the methyl ester of N-glycyl-methoxyneuraminic acid.Khimiya Prirodnykh Soedinenii, Vol. 1, No. 4, pp. 241–244, 1965     

Ternary complexes involving copper(II) and amino acids,peptides and DNA constituents. The kinetics of hydrolysis of α-amino acid esters

Binary and ternary complexes of copper(II) involving picolylamine (Pic) and amino acids, peptides (HL) or DNA constituents have been investigated. Ternary complexes of amino acids or peptides are formed by simultaneous reactions. Amino acids form the Cu(Pic)L complex, whereas peptides form Cu(Pic)L and Cu(Pic)(LH_–1). The ternary complexes of copper(II) with picolylamine and DNA are formed in a stepwise process, whereby binding of copper(II) to picolylamine is followed by ligation of the DNA components. The stability of the ternary complexes is compared with the stabilities of the corresponding binary complexes. The hydrolysis of glycine methyl ester (MeGly) is catalysed by the Cu(pic)²⁺ complex. The kinetic data is fitted assuming that the hydrolysis proceeds in two steps. The first step, involving coordination of the amino acid ester by the amino and carbonyl groups, is followed by rate-determining attack by the OH^– ion. The second step involves equilibrium formation of the hydroxo-complex, Cu(pic)(MeGly)(OH), followed by intramolecular attack.