New Aspect of Nucleophilic Reactivity of Tertiary Phosphine Oxides. R3PO-POCl3 Binary System

The reaction of tertiary phosphine oxides with phosphorus oxychloride was found to give triorganylphosphonium dichlorophosphates R₃PCl⁺PO₂Cl₂ ^- rather than phosphorylphosphonium salts R₃P·OPOCl₂. Mixtures of the reagents, called binary system, possess a considerable synthetic potential. They are capable of converting alcohols to the corresponding alkyl chlorides.     

Carbohydrates from Lamiaceae. VIII. α-Glucan from <Emphasis Type="Italic">Scutellaria baicalensis</Emphasis> roots

The homogeneous polysaccharide S _b RP-1″ with MW 110 kDa was isolated during an investigation of water-soluble polysaccharides from Scutellaria baicalensis roots. Its aqueous solution gave a positive reaction with iodine and exhibited high specific rotation ([α]_D +188.0°). Chemical, chromatographic, and spectral methods established that S _b RP-1″ was a slightly branched glucan containing in the main chain α-(1 → 4)-glucopyranose units, 8.3% of which were branched at the C-6 atom with single α-glucopyranose units. Glucan S _b RP-1″ was shown to exhibit immunostimulating activity using an azathioprine model of immunosuppression.     

Synthesis of benzotriazolylsuccinimides in melt

N-Phenyl-3-(benzotriazol-1-yl)pyrrolidine-2,5-dione was synthesized by condensation of N-phenylmaleimide with benzotriazole in melt. The adducts of 2 moles of benzotriazole to different bismaleimides, namely, bis[3-(benzotriazol-1-yl)pyrrolidine-2,5-diones] were obtained under analogous conditions. These adducts, according to the data from ¹H and ¹³C NMR spectroscopy, contain also (benzotriazol-2-yl)succinimide and residual maleimide fragments.     

Generation and properties of hydrogenation catalysts based on palladium bisacetylacetonate and lithium alkoxyhydroaluminates

Generation and properties of a catalytic system for hydrogenation, based on Pd(acac)₂ and LiAlH₄ and modified with n-BuOH and t-BuOH, were studied. The promoting and inhibiting effects of the alcohols were revealed, and their causes were discussed.     

Formation of palladium phosphides in the reaction of bis(dibenzylideneacetone)palladium(0) with white phosphorus

The reaction of bis(dibenzylideneacetone)palladium(0) with white phosphorus was studied using the methods of NMR, UV spectroscopy, and X-ray powder diffraction. The products of the reaction are shown to be palladium phosphides, their composition depending on the ratio of the reagents. The mechanism of the formation of the palladium-enriched phosphides is suggested, which includes the formation of palladium diphosphide PdP₂ that subsequently reacts with the excess of bis(dibenzylideneacetone)palladium(0) leading to palladium phosphides Pd₅P₂, Pd₃P_0.8, Pd_4.8P, and free dibenzylideneacetone.     

Synthesis of Polynuclear Nonfused Azoles

Polynuclear blocks consisting of nonfused heterocycles of the azole series, connected through methylene bridges, were synthesized by successive addition of azole units via cycloaddition of organic azides to the triple bond of N-(2-propynyl)azoles, as well as via reaction of azide ion at the cyano group of cyanomethylazoles. Initial N-(2-propynyl)azoles were prepared by reaction of 2-propynyl bromide with 1,2,3-triazoles, benzotriazole, and tetrazoles; cyanomethylazoles were obtained by alkylation of azoles with chloroacetonitrile. An analogous scheme was used to add heterocyclic units to 2-phenyl-1,2,3-triazole-4-carbonitrile. In this case, the first two heterocyclic units are linked through the ring carbon atom.     

Polysaccharides of Fabaceae. II. Galactomannan from <Emphasis Type="Italic">Astragalus danicus</Emphasis> seeds

Galactomannan of molecular weight 472 kDa was isolated from Astragalus danicus Retz. (Fabaceae) seeds and consisted of galactose and mannose units in a 1:1.40 molar ratio. The main chain of the macromolecule was constructed of 1,4-β-D-mannopyranose units, 71% of which were substituted at C-6 by single α-D-galactopyranose units. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 255257, May-June, 2009.