Superacid cyclization of esters of some bishomoisoprenoid acids

It is shown that on the superacid cyclization of esters of bishomobicyclogeranylgeranic and E,E-bishomofarnesic acids fully cyclized hydroxyesters are formed in good yield, while on the interaction of esters of 6-hydroxy- and 6-acyloxy-15-bishomobicyclogeranylgeranic acids with a superacid no carbocyclization takes place.Institute of Chemistry, Moldovian Academy of Sciences, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 645–653, November–December, 1992.     

Synthesis of esters of n-6-purinylamino acids

Reaction of esters of amino acids with 6-chloropurine gives a series of hitherto unknown esters of N-6-purinylamino acids, which are potential kinins. The IR spectra of these compounds are determined to characterize them.     

Positional isomers of thienopyrimidinones

Condensation of o-cyanomethylbenzoic acids with esters of 2-aminothiophene-3-carboxylic and 3-amino-thiophene-2-carboxylic acids to give isomeric 2-(4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-2-ylmethyl)-benzoic acids and their ethyl and phenacyl esters. Methylation of esters occurs at N-3. The spectroscopic characteristics of the positional isomers are compared at the level of carboxylic acids, their esters, and methylated products. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, 932–941, June, 2008.     

Chemistry of polyenic and polyynic compounds

Conclusions A method is described for the synthesis of some cyano aldehydes, cyano esters, esters of dichloro acids, and esters of amino acids of the polyenic series.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1334–1338, June, 1967.     

Synthesis and reduction of esters of N-(4-amino-5-nitro-6-pyrimidyl)amino acids

The reaction of esters of amino acids with 4-amino-6-chloro-5-nitropyrimidine has yielded esters of (4-amino-5-nitro-6-pyrimidyl)amino acids. The reduction of the esters of -(4-amino-5-nitro-6-pyrimidylamino) acids has yielded 4-amino-6-hydroxy-7,8-dihydropteridines. -(4-Amino-5-nitro-6-pyrimidylamino) acids and the ester of N-(4-amino-5-nitro-6-pyrimidyl)--alanine do not cyclize and on reduction give the corresponding diaminopyrimidine derivatives.     

Amino acids and peptides. XXIII. Synthesis of N alpha-protected amino acid 6-chloro-2-pyridyl esters and their evaluation for peptide synthesis

6-Chloro-2-pyridyl esters (OPyCl) of N alpha-benzyloxycarbonyl and tert-butyloxycarbonylamino acids were synthesized by the N,N'-dicyclohexylcarbodiimide (DCC) method from the acids and 6-chloro-2-hydroxypyridine in dimethylformamide (DMF). The reactivity of the 6-chloro-2-pyridylester with amino group is much higher than that of the corresponding 2-pyridyl ester (OPy) and p-nitrophenyl esters (ONp) in dioxane and DMF, and a peptide bond is formed without acylation at the side chain hydroxyl group of amino acids. Z-Asp(OBzl)-OPyCl reacted with amino acid methyl esters in dioxane to give the corresponding dipeptide without any detectable aspartimide formation.     

Vanillin Esters of Aliphatic Acids in the Synthesis of 4,7-Phenanthroline Derivatives

Condensation of vanillin esters of aliphatic acids with 6-aminoquinoline and cyclic c-diketones (1,3-cyclohexanedione and dimedone) afforded new 2-methoxy-4-(11-oxo-7,8,9,10,11,12-hexahydrobenzo[b][4,7]phenanthrolin-12-yl)phenyl esters of carboxylic acids.     

Method for evaluating the bioconversion of radioactive polyunsaturated fatty acids by use of reversed-phase liquid chromatography

Reversed-phase high-performance liquid chromatography on a thermostatted octadecylsilyl column was used to separate mixtures of labelled polyunsaturated fatty acids (as their methyl esters) formed by successive desaturations and elongations of labelled linoleic (18:2 n - 6) or linolenic (18:3 n - 3) acid by rat liver microsomes. Acetonitrile-water mixtures were used for elution of the esters. Unsaturated and saturated esters were detected by their refractive indices. The order of elution of fatty acid methyl esters in complex mixtures varies as a function of the chain length and unsaturation, analysis temperature, water concentration and solvent flow-rate. The peak areas vary as a function of the unsaturation. Specific radioactivities of 14C-labelled fatty acids and the percentage distribution of radioactivity among fatty acids from complex mixtures can be efficiently determined by collection and direct measurement of the radioactivity in the solvent by liquid scintillation counting. The method can be applied to complete compositional analysis, but is especially useful for determination of specific radioactivities during studies on the metabolic conversion of labelled polyunsaturated fatty acids.     

Synthesis and structure of 5-oxo-1-phenylpyrazoline-3- and 4-alkanoic acids. Antiinflammatory agents

Condensation of appropriate β-keto esters with phenylhydrazine gave 5-oxo-1-phenyl-2-pyrazoline-3-and 4-alkanoic esters 1 and 3 which were saponified to the corresponding alkanoic acids 2 and 4 . Analogous condensation of the same β-keto esters with hydrazobenzene gave 5-oxo-1,2-diphenyl-3-pyrazoline-3-and 4-alkanoic esters 5 and 7 which were similarly converted to acids 6 and 8 . The structures of the oxopyrazolines as revealed by their infrared absorption are discussed, and results of their antiinflammatory screening are reported.     

超酸POSA催化酯化反应动力学及线性自由能关系

全氟辛基磷酸(C_8F_(17)SO_3H,Perfluorooctanesulfonic acid,POSA)是熔点为90℃的固体超酸.我们首次测得其酸度函数值是-12.11±0.03,并将其用于催化Friedel-Crafts烃基化反应和醇脱水制烯,取得了良好的结果.本文报导我们研究POSA催化酯化反应的动力学和线性自由能关系. 线性自由能关系是研究反应动力学微观过程的有效方法之一.对反应速度常数、平衡常数的测定,对于活化参数△E、△S、△H的计算以及反应机理的深入了解都是非常有用的.近年报导的Wittig反应线性自由能关系的研究即是一例. 我们测定了POSA催化对位取代苯甲酸的乙酯化反应的速率常数k,计算了反应的活化能     

Synthesis and Properties of Ethyl Esters of 4-Dialkylamino-2-methylthiothieno[2,3-d]pyrimidine-6-carboxylic Acids

The reaction of 4-dialkylamino-6-chloro-2-methylthiopyrimidine-5-carbaldehydes with ethyl mercaptoacetate in the presence of triethylamine gives the corresponding ethyl esters of thieno[2,3-d]pyrimidine-6-carboxylic acids. These esters were subjected to alkaline hydrolysis, hydrazinolysis, and lithium aluminum hydride reduction to give the corresponding acids, hydrazides, and (thieno[2,3-d]pyrimidin-6-yl)methanols.     

Synthesis of methyl esters of 5-aroyl-6-aryl-2-oxo-1,2,3,6-tetra-hydropyrimidine-4-carboxylic acids

Methyl esters of 5-aroyl-6-aryl-2-oxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acids were synthesized from three component mixtures of methyl esters of aroylpyruvic acids, urea, and substituted benzaldehydes. 8-Hydroxy-4,5-diphenyl-3,4-dihydropyrimido[4,5-d]pyridazin-2(1H)-one was synthesized by the reaction of 5-benzoyl-2-oxo-6-phenyl-1,2,3,6-tetrahydropyrimidin-4-carboxylate with hydrazine hydrate.     

Solid Superacid Catalyzed Efficient Synthesis of 2-Diethylaminoethyl Aryloxyacetates

2-Diethylaminoethyl aryloxyacetates are prepared efficiently in 75～95% yields by condensation of the corresponding aryloxY2acetic acids with 2-diethylaminoethanol in the presence of catalytic amount of solid superacid SO4 ^2-/Fe2O3.     

固体超强酸SO_4~(2-)/TiO_2对酯化反应的催化作用

1979年Hino等首先合成了SO_4~(2-)/TiO_2,SO_4~(2-)/ZrO_2等新型固体超强酸,它们有特殊的催化性能,且具有不怕水,可在高温下使用、制备方便、减少三废等优点,因此有广泛的应用前景,引起国内外催化工作者的兴趣和重视. 我们仿照Hino法合成了SO_4~(2-)/TiO_2体超强酸催化剂,测定了酸强度和比表面.本研究着眼点是取代有严重腐蚀作用的浓H_2SO_4催化剂,选用两类酯化反应考察了SO_4~(2-)/TiO_2的催     

The use of sulfated tin oxide as solid superacid catalyst for heterogeneous transesterification of <Emphasis Type="Italic">Jatropha curcas</Emphasis> oil

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).     

Synthesis of methyl esters of 5-amino-4-(substituted amino)-2-methylthio-7H-pyrrolo[2,3d]-pyrimidine-6-carboxylic acids

The optimum route for the synthesis of methyl esters of N-[(4-substituted amino)-5-cyano-2-methylthiopyrimidin-6-yl]amino acids (which are starting materials for preparing the methyl esters of the corresponding 5-amino-4-(substituted amino)pyrrolo[2,3-d]pyrimidine-6-carboxylic acids) is via subsequent reactions of 4,6-dichloro-2-methylthiopyrimidine-5-carbonitrile with amines and methyl glycinate. In some examples, the reaction of methyl N-(4-chloro-2-methylthio-6-pyrimidinyl)aminoacetate with amines occurs to give the corresponding acid amides. The previously unknown synthesized derivatives of pyrimidin-6-yl amino acids and 4,5-diaminopyrrolo[2,3-d]pyrimidine- 6-carboxylic acids possess fungicidal properties.Vilnius University, Vilnius 2006, Lithuania. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 7, pp. 955–961, July, 2000.     

Activated esters of substituted pyrazinecarboxylic acids

N-Amidino-3,5-diamino-6-chloropyrazinecarboxamide ( 1 ) has been shown to be an effective potassium sparing diuretic. Various carboxyl activating agents have been employed with 3-amino-pyrazinecarboxylic acids in an effort to synthesize analogs of 1. Stable enol esters were isolated from a number of such acids and N-t-butyl-5-methylisoxazolium perchlorate ( 12 ). Although strong bases in DMF or DMSO catalyze a competing destruction of the enol ester system, these esters are useful acylating agents for a variety of nucleophilic substrates in less polar media. Amides, esters, and thiol esters are produced in good yields under mild conditions from these activated esters.     

An unexpected reaction of 2-vinyloxyethyl isothiocyanate with halocarboxylic acids

Reactions of 2-vinyloxyethyl isothiocyanate with aliphatic halocarboxylic acids give rise to their 1-(2-isothiocyanatoethoxy)ethyl esters in quantitative yields. An unusual rearrangement of 1-(2-isothiocyanatoethoxy)ethyl chloro(bromo)acetate and 3-bromopropanoate to 5-aza-7-chloro(bromo)-4-oxo-3-thiaheptanoic and to 6-aza-8-bromo-5-oxo-4-thiaoctanoic acids, respectively, was observed. Monohalocarboxylic acids and their esters were shown to readily alkylate l,3-oxazolidine-2-thione to form the same thiaheptanoic and thiaoctanoic acids and their esters.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–354, February, 1993.     

BTISA-catalyzed Friedel-Crafts bimolecular cyclization of cinnamic acid under superelectrophilic solvation conditions

Friedel-Crafts bimolecular cyclizations of cinnamic acid and cinnamoyl chloride with aromatic compounds in strong and superstrong acids in present of 1 mol% BTISA were investigated. It was demonstrated that catalytic amounts of this new superacid have essential effect on such type of reactions. Its use makes possible the preparation of indanones with quantitative yields.     

Synthesis of regioisomeric 6,9-(chlorofluoro)-substituted benzo[g]quinoline-5,10-diones,benzo[g] isoquinoline-5,10-diones and 6-chloro-9-fluorobenzo[g]quinoxaline-5,10-dione

Treatment of difluoro or chloro fluoro-substituted benzyl bromides 5a-c with zinc dust in tetrahydro-furan leads to the corresponding benzylic zinc bromides 6a-c. These organometallics on treatment with chlorosubstituted heterocyclic esters 4A and 4B mediated by nickel catalysis undergo couplings to yield dihalobenzyl substituted heterocyclic esters 7Aa-c and 7Ba-c. Treatment of 4c with 6c under Pd catalysis leads to 7Cc. The acids 8, prepared by hydrolysis of these esters, with treatment of fuming sulfuric acid undergo cyclizations and oxidations to yield the desired regioisomeric dihalo-substituted heterocyclic quinones 2.