Preparation of trimethylsilyl derivatives of amino acids and peptides for peptide synthesis

Russian Chemical Bulletin -     

Die Pentafluoro-orthoselen- und -orthotellurgruppe,eine 19F-Kernresonanzuntersuchung

A ¹⁹F-NMR Study of the (Pentafluoro)orthoselenium and -tellurium Group In ¹⁹F-nmr the (pentafluoro)orthoselenium and (pentafluoro)orthotellurium groups show characteristic AB₄ spectra. Chemical shifts give information about the different bondings. The axial fluori ne atom is often more influenced, a certain trans effect may be discussed. The values of is otopic splittings, coming from ⁷⁷Se agree with these observations, isotopic splittings from ¹²³Te und ¹²⁵Te are much less important. Comparison is done with selected compounds containing a (pentafluoro)orthosulphur group.     

Skeletal ruthenium catalyst in asymmetric hydrogenation

Conclusions Skeletal ruthenium catalyst, modified with D-(+)-tartaric acid, leads to the asymmetric hydrogenation of the carbonyl group in acetoacetic ester.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, p. 2361, October, 1972.     

Hydrocarbomethoxylation of 1-hexene with formic acid and methanol under conditions of phosphoric acid catalysis

Conclusions When the hydrocarbomethoxylation of 1-hexene with formic acid is run at atmospheric pressure and temperatures close to room temperature, in the presence of conc. H₃PO₄, an increase in the relative amount of the latter, as well as an increase in the reaction temperature in the investigated range, both favor an increase in the yields of the methyl esters of the C₇ acids, in particular, those containing two methyl groups on the quaternary carbon atom in the -position. An increase in the relative amount of formic acid also favors an increase in the amounts of these esters in the obtained mixtures of esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1116–1118, May, 1971.     

Reaction of onium salts with nucleophilic reagents

Russian Chemical Bulletin -