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Vol 94, No 7 (2024)
Articles
Synthesis of Formylphenyl 1-Oxo-1,2,3,6,7,7a-hexahydro-3a,6-epoxyisoindole-7-carboxylates and Their (E)-1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-yliminomethyl Derivatives
Abstract
Formylphenyloxohydroepoxyisoindole carboxylates were prepared by the reaction of 4-hydroxy-3-methoxy-, 4-hydroxy-3-ethoxy- and 3-hydroxy-4-methoxybenzaldehydes with substituted isoindolecarboxylic acids {2-methyl-1-oxo-1,2,3,6,7,7a-hexahydro-3a,6-epoxyisoindole-7-carboxylic, 2-(3,4-dimethoxyphenethyl)1-oxo-1,2,3,6,7,7a-hexahydro-3a,6-epoxyisoindole-7-carboxylic, 2-(benzo[d][1,3]dioxol-5-ylmethyl)-1-oxo1,2,3,6,7,7a-hexahydro-3a,6-epoxyisoindole-7-carboxylic, 6-oxo-3,4,6,6a,7,8-hexahydro-2H,10bH-8,10a-epoxy[1,3]oxazino[2,3-a]isoindole-7-carboxylic, 2-(2,3-dichlorobenzyl)-1-oxo-1,2,3,6,7,7a-hexahydro-3a,6-epoxyisoindole-7-carboxylic} in dichloromethane in the presence of dicyclohexylcarbodiimide. The corresponding (E)-azomethines were synthesized by condensation of formylphenyloxohydroepoxyisoindole carboxylates with 4-amino-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one in methanol.
786-804
Synthesis of Nitrones Based on Triterpenes C3-Hydroxylamines of the Lupane Series
Abstract
An approach was developed to the synthesis of triterpene C3-nitrones containing the amide function at C28-position, new derivatives of pentacyclic triterpenoids of the lupan series. Diastereomeric triterpene 3β- and 3α-hydroxylamines obtained by reduction of oxime based on betulonic acid isopropylamide with NaBH3CN in a solution of 2 M HCl in MeOH were used as starting compounds. Nitrones were synthesized by condensation of hydroxylamines with substituted benzaldehydes in dichloromethane in the presence of Na2SO4.
805-814
Selective Synthesis of Amino Acid Conjugates of Glycyrrhizic Acid Using N-Oxyphthalimide and N,N′-Dicyclohexylcarbodiimide
Abstract
A selective synthesis of amino acid conjugates of glycyrrhizic acid containing amino acid residues in the carbohydrate part of the glycoside was proposed using N-oxyphthalimide (HOPt) and N,N′-dicyclohexylcarbodiimide (DCC), tert-butyl and benzyl/4-nitrobenzyl esters of L-amino acids with yields of 55–60%. Free conjugates of glycyrrhizic acid with valine, isoleucine, methionine, phenylalanine, leucine, tyrosine and glutamic acid were obtained by deblocking the ester groups.
815-822
Bis(N-Alkyl-N-diphenylphosphinylmethyl)diglycolamides: Synthesis and NMR Spectroscopy Study
Abstract
Bis(N-Alkyl-N-diphenylphosphinylmethyl)diglycolamides [Ph2P(O)CH2N(R)C(O)CH2]2O, where R = Et, i-Pr, n-Bu, i-Bu, n-Oct, were synthesized by reaction of diglycolyl chloride with N-alkyl-N-(diphenylphosphinylmethyl)amines Ph2P(O)CH2NHR obtained by the Kabachnik–Fields reaction of aminomethylation of diphenylphosphinous acid, and their hydrochlorides. The structure of the obtained compounds was studied by 1H, 13C and 31P NMR spectroscopy.
823-835
Reactions of Pyrimidine-2-sulfenyl Chloride with Alkylvinyl and Allyl Ethers
Abstract
The regioselective synthesis of novel thiazolo[3,2-a]pyrimidine derivatives in 52–92% yields was developed based on the reaction of pyrimidine-2-sulfenyl chloride with unsaturated ethers. The reaction with allylic and vinylic ethers proceed regioselectively, but with the opposite regiochemistry. The reaction with allylic ethers lead to 2-substituted thiazolo[3,2-a]pyrimidine derivatives whereas 3-organyloxy derivatives are formed in the reaction with vinylic ethers.
836-842
Synthesis of Tetraoxacalixarenes Based on Ethyl Pentafluorobenzoate. Effect of Solvent Polarity and Nature of the Base
Abstract
The direction of reaction of ethyl pentafluorobenzoate with orcinol depends largely on the polarity of the solvent and the nature of the base. In acetonitrile the reaction proceeds exclusively in the para-position of ethyl pentafluorobenzoate, while in the dioxane–Na2CO3 system the products of substitution of fluorine atoms in the ortho-position are predominantly formed. The reaction of triphenyl with orcinol in the dioxane–K2CO3 system leads to the formation of a mixture of possible fluorine-containing isomeric tetraoxacalixarenes. The corresponding fluorine-containing tetraoxacalixarenes with carboxyl group were obtained by hydrolysis of ester groups.
843-855
Chemical Stability of Ln[(UO2)3O3.5(OH)2]·5H2O (Ln = La, Ce, Pr and Nd) Compounds in Aqueous Solutions
Abstract
The chemical stability of Ln[(UO2)3O3.5(OH)2]·5H2O (Ln = La, Ce, Pr, Nd) compounds in aqueous solutions in a wide range of medium acidity was studied. The acid-base intervals of the existence of compounds in aqueous solutions have been established, and solubility was determined. Based on the data obtained, the equilibrium constants of heterogeneous reactions and the Gibbs function of Ln[(UO2)3O3.5(OH)2]·5H2O formation were calculated, solubility curves of the studied compounds were calculated, diagrams of the state of U(VI) and Ln(III) in aqueous solutions were constructed.
856-867
Powder Adhesion Promoters Based on Hydrolysis Lignin for Rubbers
Abstract
Powder adhesion promoters for rubbers based on hydrolysis lignin were obtained by its treatment with TiCl4 solution in C6H14. The physical-chemical properties of the obtained products were determined: bulk density, content of Ti(IV), carbonyl, carboxyl groups, acid-insoluble lignin. The obtained powder adhesion promoters were introduced into rubber compound in the amount of up to 5 phr (parts per 100 of rubber). Butadiene-α-methylstyrene rubber grade SBR-1705 HI-AR was used. The effect of the promoters on the kinetic parameters of vulcanization and physical-mechanical properties of rubbers was studied. It was revealed that the introduction of the studied powder promoters of adhesion into the rubber compound allows to increase the bond strength at the interface rubber–brass-plated metal cord by 2–3 times.
868-880