A novel method for synthesizing diorganylphosphinous acids from red phosphorus and arylalkenes

The reaction of styrene and -methylstyrene with P in aprotic polar solvents in the presence of KOH affords diorganylphosphinous acids.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1680–1681, September, 1994.     

An unusual new reaction of α-olefins with magnesiumn-alkyl derivatives catalyzed by Cp2ZrCl2

The reaction of organomagnesium compounds (OMC) containing alkyl radicals of normal structure with -olefins, resulting in the formation of alkenylorganomagnesium compounds and accompanied by hydride transfer was discovered and systematically investigated. A scheme providing for the formation of zirconacyclopentane complexes was proposed for the mechanism of the reaction.Institute of Organic Chemistry, Ural Branch, Russian Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1187–1196, May, 1992.     

Novel optically active 1,3-aminoalcohols derived from D-glucal

A series of ethyl(phenyl) 6-amino-2,3,6-trideoxy--D-glucopyranosides (amino=piperidino (Pip), pyrrolidino (Pyr), azetidino (Az), Bu₂N) have been prepared from tri-O-acetyl-D-glucal to obtain catalysts for asymmetric synthesis and the starting compounds for the syntheses of other bidentate ligands.Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 45–52, January, 2000.     

Investigation of gas chromatographic interaction mechanism on permethylated cyclodextrins by molecular modelling

Summary The capillary gas chromatographic retention behavior of -pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before -pinene; only permethylated -cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated -cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances.     

MNDO study of reaction paths: Diboration of acetylene

The reaction of B₂H₄ with acetylene has been studied by the MNDO method. It is shown that the reaction is exothermic and proceeds in two steps. The first step is the formation of a three-center -complex and this is the rate-determining step of the reaction. The second step is the rearrangement of the -complex to the product and this step requires a very small amount of activation energy. The activation barrier for the diboration reaction is 12.8 kcal/mol.The proposed mechanism is significantly different from those proposed earlier and explains all experimental data relating to this reaction.     

Synthesis of some phosphonocarbonyl compounds via Horner-Emmons reaction of methylenbisphosphonate

Summary The -carbonyl substituted vinylphosphonates6–9 were synthesized from the -dicarbonyl compounds2–5 and the methylenbisphosphonate1 by a Horner-Emmons reaction in different yields.

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Synthese von Phosphonocarbonylverbindungen durch Horner-Emmons-Reaktion von Methylenbisphosphonsäuretetraethylester

Zusammenfassung Es wurden die -carbonylsubstituierten Vinylphosphonate6–9 mittels Horner-Emmons-Reaktion aus den -Dicarbonylverbindungen2–5 und Methylenbisphosphonat1 in verschiedenen Ausbeuten hergestellt.

     

Synthesis and structure of novel derivatives of thieno[2,3-b]thiocine. An unusual product of intramolecular cycloaddition of 2-homomethallylthio-5-methyl-3-thiophenecarbonitrile oxide

9-Methyl-3,3a,4,5-tetrahydro-6H-thieno[2,3-b]thiocino[4,5-c]isoxazole and 9-hydroxyimino-2-methyl-7-methylene-6, 7,8,9-tetrahydro-5H-thieno[2,3-b]thiocine have been prepared for the first time by the oxidation of 2--alkenylthio-3-thiophenecarbaldoximes with NaOCl. X-ray structural investigations of thieno[2,3-b]thiocine and 2-homomethallylthio-5-methyl-3-thiophenecarbaldoxime have been carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1262–1266, July, 1993.