Hydrosilylation of unsaturated fluorinated esters and ethers with hydrochlorosilanes

Hydrosilylation of allyl esters of fluoro acids and ethers of fluoro alcohols with hydrochlorosilanes in the presence of the Speier’s catalyst was studied. Yields of adducts with ethers reach 62–68%, and with esters, 27–45%. By etherification of the adduts with ethers the respective ethoxysilanes were obtained in 41–43% yield. The latter reaction even in very mild conditions is complicated by the formation of a large amount of siloxanes. Yield of siloxanes is 22–32%.     

Synthesis of heterocycles with polyfluoroalkyl substituents from unsaturated compounds containing polyfluoroalkyl groups. (Review)

Methods for the construction of heterocyclic systems containing polyfluoroalkyl substituents from derivatives of ethylene and acetylene are discussed. It is shown that various compounds with polyfluoroalkyl groups can be used as building blocks: α,β-unsaturated carbonyl compounds, their synthetic organosilicon equivalents (silyl-substituted alcohols, silyl ethers of enols), and also sulfones, nitriles, polyfluoroalkenes (in reactions at the double bond), acetylenecarboxylic acids, their esters, and polyfluoroalkynes. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 323–360, March, 2006.     

A thorough study of the surface wax of apple fruits

The composition of the surface waxes of three apple ( Malus domestica L.) cultivars ("Florina", "Golden B" and "Ozark Gold") has been studied by means of spectroscopic and GC–MS analysis of the class-fractionated mixture of components. Odd n -alkanes, mainly C₂₇ and C₂₉ molecules, are prevalent in the saturated fraction. Small concentrations of alkenes were also found; the C_28:1 component is strongly (72%) in excess over the other 1-alkenes. Straight-chain esters (mainly of palmitic acid) of saturated primary alcohols (C₁₈–C₃₀) were also detected; whereas the acyl moiety is made up essentially of an even number of carbons, the alcohol counterpart does not exhibit this characteristic. Aldehydes are present (C₂₀–C₃₀) with the homologue patterns C₂₆–C₃₀ most strongly represented. Straight-chain free secondary alcohols characterize the waxes of "Florina" and "Ozark Gold"; the hydroxy function is located far from the extremity of the carbon framework. Outstanding is the presence of three alcohols with 29 carbon centres. These alcohols are accompanied by free straight-chain primary alcohols, mainly with even-numbered carbon chains in the range C₂₆–C₃₀. Free fatty acids are present; all of have a framework of even-numbered carbon chains mainly in the range C₁₆–C₂₀. C_18:1 (oleic acid) is well represented.     

A simple and mild derivatization method for hydroxyl compounds using condensation agent carbazole-9-N-(2-methyl)-acetyl-benzene-disulfonate and its application for the determination of volatile alcohols from plasma by HPLC with fluorescence detection

A simple and sensitive HPLC method for the determination of hydroxyl compounds including volatile alcohols from spiked plasma, using a fluorescent condensation agent, namely carbazole-9-N-(2-methyl)-acetyl-benzene-disulfonate (CMABS), has been developed. A mixture of alcohols and pyridine in dichloromethane was treated with CMABS to give a quantitative yield of esters. The maximum fluorescence emissions for the derivatized alcohols are at 365 nm (λ_ex 335 nm). Studies on derivatization conditions indicate that alcohols react very fast with CMABS in presence of pyridine in dichloromethane to give the corresponding fluorescent derivatives. The method, in conjunction with a multi-step gradient, offers a baseline resolution of the common alcohol derivatives on a reversed-phase C₁₈ column, which is more convenient and more efficient than previous methods which require the prior conversion of the carboxylic acids to the acyl chlorides. The application of this method to the analysis of volatile alcohols in plasma was also investigated. The LC separation shows good selectivity and reproducibility for alcohol derivatives. The relative standard deviations ?(n = 5) for 100 pmol of each alcohol are < 4%. The detection limits are at the fmol level for C₁–C₃ alcohols and pmol level for C₄–C₉ alcohols. Received: 9 November 1998 / Revised: 3 May 1999 / Accepted: 6 May 1999     

Lipids of the fruit of Feijoa sellowiana

The composition and amounts of liposoluble substances in the flesh and peel of feijoa fruit has been investigated. About 30 groups of lipid substances have been identified. The main groups of lipids in the flesh were triacylglycerols, sterols, cerebrosides, ceramide phosphate inositol oligosides, sulfoquinovosyldiacylglycerols, phosphatidic acids, phosphotidylglycerols and phosphatidylcholines. In the peel, hydrocarbons, sterols, esters of fatty acids and lower alcohols, cerebrosides, digalactosyldiacylglycerols, ceramide oligosides, phosphatidylglycerols, and include predominated. The fatty acids of the flesh were found to include 15 representatives (C_12:0–C_28:0), and those of the flesh 11 representatives tives (C_12:0–C_18:3). M. V. Lomonosov Technological Institute of the Food Industry, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 464–467, July–August, 1991.     

Synthesis and investigation of the stability of esters of 6′-carbamoylmethylthio-5′-cyano-1′,4′-dihydro-3,4′-and-4,4′-bipyridine-3′-carboxylic acids 1. Esters of 6′-carbamoylmethylthio-5′-cyano-1′,4′-dihydro-3,4′-bipyridine-3′-carboxylic acids

Esters of 6′-carbamoylmethylthio-5′-cyano-1′,4′-dihydro-3,4′-bipyridine-3′-carboxylic acids are obtained by the alkylation of piperidinium 3′-alkoxycarbonyl-5′-cyano-1′,4′-dihydro-3,4′-bipyridine-6′-thiolates with iodoacetamide. For an HPLC study of the stability of solutions of the abovementioned 1,4-dihydrobipyridines (solution pH 2.3–9.0) the appropriate esters of 6′-carbamoylmethylthio-5′-cyano-3,4′-bipyridine-3′-carboxylic acids and esters of 8-cyano-5-methyl(or phenyl)-3-oxo-7-pyridin-3-yl-2,3-dihydro-7H-thiazolo[3,2-a]pyridine-6-carboxylic acids were synthesized as reference compounds. Analysis by HPLC was carried out under conditions of reverse-phase chromatography. It was shown that solutions of the investigated compounds in a mixture of acetonitrile and phosphate buffer (pH 3.0–5.0) were stable for 1 month on storage protected from light. Under the action of light in all the solutions investigated irrespective of pH the formation occurs of the corresponding esters of 6′-carbamoylmethylthio-5′-cyano-3,4′-bipyridine-3′-carboxylic acids. The presence of esters of 8-cyano-5-methyl(or phenyl)-3-oxo-7-pyridin-3-yl-2,3-dihydro-7H-thiazolo[3,2-a]pyridine-6-carboxylic acids (no more than 4%) was detected only in 0.1% solutions of phosphoric acid (pH 2.3) under conditions of storage of the latter protected from light. A series of as yet unidentified products was detected in solutions of pH 7.0–9.0. Dedicated to E. Lukevics on his 70th birthday __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 59–68, January, 2007.     

DSC and FTIR study of the gamma radiation effect on cis-1,4-polyisoprene

The effect of γ-radiation on the cis-1,4-polyisoprene in the presence of oxygen is investigated by ATR-FTIR technique and non-isothermal DSC measurements. FTIR measurements have shown that the formation of hydroperoxides, ketones, alcohols and/or ethers is apparent already at lower, 20–50 kGy, doses of γ-radiation and it increases significantly with the exposure time. Besides, lactones, anhydrides, peresters, carboxylic acids, and esters are formed, too. Spectral changes in the region of C=C conjugated double bonds indicate a formation of shorter polyene structures and aromatic rings. Kinetic parameters describing the temperature dependence of the induction period have been obtained from DSC measurements using the isoconversional method. Residual stabilities have been calculated in order to characterize the gamma radiation effect on polyisoprene thermooxidative stability. Both methods proved that doses lower than 50 kGy do not cause severe changes in polymer properties.     

Lipids from <Emphasis Type="Italic">Halostachys caspica</Emphasis> and <Emphasis Type="Italic">Halocharis hispida</Emphasis>

The composition of lipids from the aerial parts of two species of halophytes from the family Chenopodiaceae, Halostachys caspica C. A. Mey. and Halocharis hispida Bge. was determined. Neutral lipids (NL, 62.1 and 54.2%, respectively) dominated the total lipids (TL) of these plants. More than a third of the NL were esters of aliphatic alcohols and phytosterols (FAE). Fatty acids 16:0, 18:1, and 18:2 dominated the acids of FAE; 16:0, 18:1, and 18:3, the phospholipids. The principal fatty acids of glycolipids were unsaturated acids (68.3 and 75.1%) with linolenic acid dominating (44.9 and 43.5%). Presented at the 7th International Symposium on the Chemistry of Natural Compounds, Tashkent, October 16–18, 2007. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 276–278, May–June, 2009.     

Enzymatic synthesis and analytical monitoring of terpene ester by <Superscript>1</Superscript>H NMR spectroscopy

Terpene esters of fatty acids have potential applications in food, cosmetic, and pharmaceutical industries. The present study focuses on the synthesis of terpene esters of long chain fatty acids catalyzed by Candida antarctica lipase B. Different parameters like temperature, solvent, and enzyme concentration for the esterification of terpene alcohols (geraniol and citronellol) with oleic acid were studied. Maximum conversion (98 %) was found for both terpene esters at 60°C in 2,2,4-trimethylpentane as well as in dry hexane and around 95–97 % in other tested solvents. The reaction was also carried out using stearic and linoleic acid in hexane to study the effects of unsaturation in the substrate in which stearic acid showed the maximum conversion. The reaction was monitored by ¹H nuclear magnetic resonance spectroscopy. Using the peak integration values of methylene protons of terpene and terpene ester of δ = 3.6 and 4.0 for citronellol and δ = 4.2 and 4.6 for geraniol, respectively, percentage conversions of each of the esters were calculated.     

Stereoselective electrocatalytic cyclization of 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylic acid esters to form 6-substituted (1R,5R,6R)*-4,4-dialkoxy-5-cyano-2-oxo-3-azabicyclo[3.1.0]hexane-1-carboxylic acid esters

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.     

Synthesis of 6′-carbamoylmethylthio-5′-cyano-1′,4′-dihydro-3,4′-bipyridine-3′-carboxylic and 6′-carbamoylmethylthio-5′-cyano-1′,4′-dihydro-4,4′-bipyridine-3′-carboxylic esters and investigation of their stability. 2. Esters of 6′-carbamoylmethyl-thio-5′-cyano-1′,4′-dihydro-4,4′-bipyridine-3-carboxylic acids

The stability of solutions of esters of 6′-carbamoylmethylthio-5′-cyano-2′-methyl-1′,4′-dihydro-4,4′-bipyridine-3′-carboxylic acids was investigated by HPLC. The corresponding esters of 6′-carbamoylmethylthio-5′-cyano-4,4′-bipyridine-3′-carboxylic acids,esters of 8-cyano-5-methyl-3-oxo-7-(4-pyridyl)-2,3-dihydro-7H-thiazolo-[3,2-a]pyridine-6-carboxylic acids, methyl 3-amino-2-carbamoyl-6-methyl-4-(4-pyridyl)-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylate, and methyl 3-amino-2-carbamoyl-6-methyl-4-(4-pyridyl)-thieno[2,3-b]pyridine-5-carboxylate were synthesized as standard compounds (typical impurities). Analysis by HPLC was realized under the conditions of reverse-phase chromatography. It was established that solutions of the investigated compounds (with mixtures of acetonitrile with phosphate buffer, having pH values of not less than 3 and not more than 5, as solvents) are stable for one month when the solutions are stored in a place protected against light. It is also necessary to use chromatographic systems in which the aqueous components have pH 3–5 during determination of the purity of the esters of 6′-carbamoylmethylthio-5′-cyano-2′-methyl-1′,4′-dihydro-4, 4′-bipyridine-3′-carboxylic acid by HPLC in order to separate the analyzed sorbates and their typical impurities more completely. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 841–848, June, 2007.     

The Mitsunobu 1-O-esterification of 1-hydroxy-3-phenyl-1H-quinoxalin-2-one 4-oxide

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.     

Reformatsky-type addition of esters of α-halogeno carboxylic acids to aldehydes and ketones in the presence of Fe(CO)5

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.     

Synthesis of chiral 5-aryltetrahydrofuran-2-ones via yeast bioreduction of γ-keto acids and their esters

Enantioselective reduction of γ-keto acids and related γ-keto esters with Saccharomyces cerevisiae (baker’s yeast) leads to the formation of the corresponding chiral 5-aryltetrahydrofuran-2-ones in satisfactory chemical and optical yields. Published in Zhurnal Organicheskoi Khimii, 2006, Vol. 42, No. 3, pp. 379–382. The text was submitted by the authors in English.     

The catalytic condensation of ω-phenyl-substituted alcohols in the presence of an iron oxide

The results of gas-phase conversion of ω-phenyl-substituted alcohols (benzyl alcohol, 2-phenylethanol, 3-phenyl-1-propanol) and their equimolar mixtures with primary normal alcohol (1-octanol) are presented. Reactions were carried out at atmospheric pressure in the presence of an iron catalyst in the temperature range of 568–673 K and load of 2.0 h⁻¹. 2-Phenylethanol and 3-phenyl-1-propanol undergo dehydrogenation to aldehydes and condensation to esters. At higher temperatures symmetrical ketones containing ω-phenyl group as substituent are formed. Mixtures of these alcohols with 1-octanol give among others asymmetrical aromatic-aliphatic ketones.     

Production of biodiesel by immobilized Candida sp. lipase at high water content

A new process for enzymatic synthesis of biodiesel at high water content (10–20%) with 96% conversion by lipase from Candida sp. 99–125 was studied. The lipase, a no-position-specific lipase, was immobilized by a cheap cotton membrane and the membrane-immobilized lipase could be used at least six times with high conversion. The immobilized lipase could be used for different oil conversion and preferred unsaturated fatty acids such as oleic acid to staturated fatty acids such as palmitic acid. The changes in concentration of fatty acids, diglycerides, and methyl esters in the reaction were studied and a mechanism of synthesis of biodiesel was suggested: the triglycerides are first enzymatically hydrolyzed into fatty acids, and then these fatty acids are further converted into methyl esters.     

Unnatural amino acids. 3. Aziridinyl ketones from esters and amides of aziridine-2-carboxylic acids

A series of N-substituted amides and esters of aziridine-2-carboxylic acids have been prepared and have been subjected to deprotonation with lithium diisopropylamide. The intermediate carbanions reacted more readily with the carbonyl groups of the substrates than with methyl iodide. So, in place of the expected amides or esters of methylaziridine-2-carboxylic acids, amides or esters of 2-aziridinylcarbonylaziridine-2-carboxylic acids were isolated. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 220–225, February, 2007.     

Investigation of the Separation of Higher Fatty Acid Methyl Esters by Reversed-Phase HPTLC

JPC – Journal of Planar Chromatography – Modern TLC - Separations of eight methyl esters of higher fatty acids on RP-18 stationary phase with methanol—water and...     

Synthesis of o-carborane-C-carboxylates of certain natural terpene alcohols, sterols, phenols, and camphar oxime

Previously unreported esters 1b–20b were synthesized from natural terpene alcohols, sterols, plant phenols, and camphar oxime (1a–20a) by reaction with o-carborane-C-carboxylic acid chloride. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 434–436, September–October, 2006.     

Modifications based on coumarins III. Synthesis of diesters of karatavic and galbanic acids and mixed diesters of coumarin acids and salicylic acid with sucrose

The synthesis of 6,6′-diesters of sucrose with natural coumarins — karatavic and galbanic acids — has been achieved by the transesterification of methyl esters of these acids with monosucrose esters of the same acids, and so has that of mixed 6,6′-diesters of these coumarin acids and salicylic acid by a reaction between methyl salicylate and a monoester of the corresponding coumarin acid. The structures of the compounds obtained have been confirmed by IR, UV, PMR, and¹³C NMR spectroscopies. A. B. Bektorov Institute of Chemical Sciences, Academy of Sciences, Republic of Kazakhstan, Almaty, fax (3272) 61 57 65. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 461–465, July–August, 1998.