Synthesis of pyrylium salts and pyridine bases by the bisacylation of cyclic tertiary alcohols

The catalytic acylation of 1-methyl- and 1-ethylcyclopentan-1-ols, 1-methyl- and 1-ethylcyclohexan-1-ols, 1-methylcycloheptan-1-ol, and 1-methyl- and 1-ethyl-1-tetralols with carboxylic acid anhydrides in the presence of 70% HClO₄ has been studied. A method for the synthesis of substituted 3,4-cycloalkeno-3,4-dihydro(3,42, 1)naphthopyrylium salts and the corresponding pyridine bases has been developed.     

Structures and reactivities of benzo-1,2,3-dithiazolium salts and their selenium analogs

A number of benzo-1,2,3-dithiazolium chlorides (I) and their selenium analogs — benzo-1,2,3-thiaselenazolium, benzo-2,1,3-thiaselenazolium, and benzo-1,2,3-diselenazolium salts — were synthesized. The electronic structures and reactivities of the I cation and salts I–IV are discussed on the basis of a quantum-chemical calculation of cation I and the PMR spectra of salts I–IV. Successive substitution of the sulfur atoms in the I cation by selenium atoms, particularly in the 2 position, substantially increases the degree of transfer of positive charge to the condensed benzene ring. The trend of the nucleophilic reactivities of 6-methoxy derivatives of salts I–IV in the reaction with aromatic amines is the same as the trend of the degree of localization of the positive charge in the 6 position.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 912–916, July, 1978.     

Functionally substituted azines. 1. Synthesis and reactions of 2-(N-cyano-N-carbethoxmethylamino)-4,6-dimethylpyrimidine

Treatment of 2-(N-potassium-N-cyanamino)-4,6-dimethylpyrimidine with ethyliodoacetate produces 2-(N-cyano-N-carbethoxymethylamino)-4,6-dimethylpyrimidine. Alkaline hydrolysis of the last gives 2-(3-potassium-2,4-dioxoimidazolidinyl-1)-4,6-dimethylpyrimidine. Ammonolysis and hydrazinolysis give imino- or amino-imidazolidinylpyrimidine, respectively.Armenian Agricultural Institute, Erevan 375009. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1239–1241, September, 1994. Original article submitted August 9, 1994.     

On the ratios of the terms of second order linear recurrences

Research (partially) supported by Hungarian National Foundation for Scientific Research (OTKA) grant No. 273.     

Volumetrische Bestimmungen mit Dead stop-Indikation. VI

Zusammenfassung Silberionen können mit einer Jodid-Maßlösung unter Verwendung der Dead stop-Indikation titriert werden. Das sprunghafte Anwachsen der Stromstärke wird durch das Jod bedingt, das aus dem Jodidüberschuß durch Kaliumdichromat freigesetzt wird. In Gegenwart von Quecksilberionen kann die Summe aus Quecksilberionen und Silberionen titriert werden. Die Menge an Quecksilberionen kann dann durch Titration mit Thiosulfationen bestimmt werden. Aus der Differenz der beiden Messungen ergibt sich der Gehalt an Silberionen. Die Methode eignet sich auch zur Analyse von Silberamalgamen.Vgl. dazu Kiss, S. A.: diese Z. 194, 104 (1963).Auf diesem Weg sei mein Dank meiner Mitarbeiterin Frau B. R. Doszpod ausgesprochen für die Hilfe, die sie bei der Durchführung der Messungen leistete.     

Diterpenoids ofPulicaria salviifolia. III. The structure of salvicinin

The new diterpene acid salvicinin has been isolated from the epigeal part ofPulicaria salviifolia and its structure has been established as 15-acetoxy-6α-hydroxy-trans-cleroda-3,13-dien-19-oic acid. A capacity of salvicinin for undergoing lactonization in the presence of acetic anhydride has been revealed, and the lactone formed has been isolated and chracterized.     

Ma?analyse und Katalyse

Zusammenfassung Die Anwendung der katalytisch-thermometrischen Endpunktsindikation bei Substitutionstitrationen und bei Titrationen in nichtwäßrigem Medium (DMSO) wird beschrieben. Zahlreiche Metalle, sowie die Komplexbildner ÄDTA, DCTA und NTA können in Mikrogrammengen mit ausreichender Genauigkeit bestimmt werden.

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Volumetric analysis and catalysisVII. Thermometric end-point indication of substitution titrations and titrations in non-aqueous medium (DMSO)

The application of the catalytic-thermometric end-point detection to substitution titrations and titrations in non-aqueous medium (DMSO) is described. Numerous metals as well as the chelating agents EDTA, DCTA and NTA can be determined in the microgram-range with reasonable accuracy.

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Teil VI: Klockow, D., García Beltrán, L.: diese Z. 249, 304 (1970).

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Der Autor dankt der Alexander von Humboldt-Stiftung, welche diese Arbeit durch ein Dozentenstipendium ermöglicht hat.     

Diterpenoids ofPulicaria salviifolia IV. Structures of salvicinolide and salvicinolin

Two new clerodanolides — salvicinolide and salvicinolin — have been isolated from the epigeal part ofPulicaria salviifolia Bge inMem (fam. Compositae). Their structures have been established by an investigation of their spectral and physicochemical characteristics. It has been found that salvicinolide is capable of cyclizing at the C-6 and C-19 carbon atoms with the formation of a second lactone ring. The structure of 6-hydroxy-19-carboxy-trans-clero-3,13-dien-15-olide is proposed for salvicinolide, and 6,13-dihydroxy-19-carboxy-rans-cleroda-3,13-diene for salvicinolin.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent fax (3712) 40 64 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 594–598, July–August, 1997.     

Synthesis of heparin saccharides IV. Synthesis of disaccharides possessing the structure of a repeating unit of heparin.

The synthesis of disaccharides possessing the structure of a repeating unit of heparin is reported. 2-Acetamido-2-deoxy-4-O-(methyl α-D-glucopyranosyluronate)-D-glucopyranose ( 1 ) and 2-[1-(benzyloxy)formamido]-2-deoxy-4-O-(methyl α-D-glucopyranosyluronate)-D-glucopyranose ( 2 ) have been prepared by two routes, (a) from D-glucose and D-glucosamine, and (b) from D-glucuronolactone and D-glucosamine.     

Interactions of Al(III) with a neurofilament heptapeptide fragment: AcLysSerProValValGluGly

The solution state of the neurotoxic Al(III) in biological systems is discussed briefly, and the importance of the Al(III)-peptide and Al(III)-protein interactions in the various neurodegeneration processes is emphasised and evaluated. The possible involvement of Al(III) in the formation of Alzheimer's disease marker senile plaques and neurofilament tangles is discussed in light of the solution speciation of the Al(III)-AcLysSerProValValGluGly system and the structural features of the complexes formed.