Reaction of unsymmetrical α,β-unsaturated ketones with thiobarbituric acid

Carbocyclization of unsymmetrical 1,5-diarylpenta-1,4-dien-3-ones with thiobarbituric acid afforded previously unknown 7,11-diaryl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-triones with high regio- and stereoselectivity. The same spiro compounds were also synthesized by three-component condensation of thiobarbituric acid with the corresponding aromatic aldehydes and 4-arylbut-3-en-2-ones.     

Addition of hydrohalic acids to acetylenic ketones of the thiophene series

The synthesis of -chloro(bromo)vinyl ketones of the thiophene series was accomplished by the addition of hydrogen chloride and hydrogen bromide to acetylenic ketones of the thiophene series. The sequence of addition of the hydrogen halide was proved by alternative synthesis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1350–1352, October, 1971.     

Saturated nitrogen-containing heterocycles. 12. Stereochemical properties of hydroxyalkylpyrrolidines using 13C NMR spectroscopy

The ¹³C NMR spectra of fifteen compounds in a series of alkyl- and arylsubstituted cis-isomers of hydroxyalkylpyrrolidines have been recorded, and they have been fully interpreted on the basis of configurational and conformational assignments.For Communication 11, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1201–1204, September, 1988.     

Polysaccharides of Algae 71*. Polysaccharides of the Pacific brown alga <Emphasis Type="Italic">Alaria marginata</Emphasis>

The polysaccharide composition in sporophylls of the brown alga Alaria marginata enriched with laminaran and sulfated polysaccharides was studied. It was shown that laminaran molecules had an average degree of polymerization about 30 and consisted mainly of 3-linked β-D-glucopyranose residues, having no more than 10% of 1→6 linkages. The majority of chains (about 60%) were terminated at "reducing" end by mannitol residue. Alginic acid of sporophylls contained mannuronic (M) and guluronic (G) acids residues distributed along the linear polymer molecules as MM, MG, and GG blocks at a ratio of 4: 1: 1. Fucoidan was found to be composed of fucose, galactose, and sulfate as the major constituents, while xylose, mannose, glucuronic acid, and acetate were the minor components. It was shown that fucoidan contained two major components: fucan sulfate, molecules of which are built up of 3-linked fucopyranose residues with branches and sulfate groups at different positions, and fucogalactan, also containing chains of 3-linked fucopyranose residues with branches at positions 4 together with highly branched galactan chains terminated by fucose residues. The fucoidan contained also sulfated glucuronomannan and sulfated glucuronan as minor components.     

Polysaccharides of algae 68. Sulfated polysaccharides from the Kamchatka brown alga Laminaria bongardiana

Several fucoidan fractions were isolated from the biomass of the Kamchatka brown alga Laminaria bongardiana by hot water extraction followed by anion-exchange chromatography. Fucoidans were found to be composed of l-fucose, d-galactose, and sulfate as the major components, whereas d-xylose, d-mannose, d-glucuronic acid, and acetate were detected as the minor constituents. Highly sulfated fucoidan fractions F-2 and F-3 were solvolytically desulfated by heating in dimethyl sulfoxide in the presence of pyridine. The structures of native and desulfated polysaccharides were investigated by the methylation analysis and NMR spectroscopy. It was shown that F-2 contains fucan sulfate, the backbone of which is made of 1→3-linked α-l-fucopyranose residues with single α-l-Fucp branches at positions 2 and sulfate groups predominantly at positions 4. Sulfated fucoglucuronomannan, fucoglucuronan, and fucogalactan were detected in F-2 as concomitant polysaccharides. Fucan sulfate and sulfated fucogalactan were the major components of the fraction F-3. The anticoagulant properties of fucoidan fractions were assessed. It was demonstrated that the activity of the fraction F-3 is comparable with that of low-molecular-weight heparin (enoxaparin), whereas the activity of total fucoidan F and the fraction F-2 is ~2/3 and ~1/2, respectively, of the activity of F-3, which is in accordance with the lower sulfate content in these samples. Desulfated preparations F-2deS and F-3deS were completely devoid of anticoagulant activity.

     

Saturated nitrogen heterocycles. 11. Catalytic synthesis of 2-pyrrolidylalkanols

Furylakylamines have been catalytically converted into novel isomers of 2-pyrrrol-idylalkanols bearing a secondary alcohol group in the aliphatic chain, or a tert-butyl group attached to the heterocycle.For Communication 10, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1058–1061, August, 1988.     

Polysaccharides of Algae 58. The polysaccharide composition of the Pacific brown alga <Emphasis Type="Italic">Alaria fistulosa</Emphasis> P. <Emphasis Type="Italic">et</Emphasis> R. (Alariaceae,Laminariales)

Quantitative determination of mannitol, fucoidan and alginate in different parts of the thallus (the blade, the midrip, the sporophylls, and the stipe with rhizoids) of the brown alga Alaria fistulosa, collected from the coastal waters of Paramushir Island, was carried out. Sporophylls were shown to differ considerably in carbohydrate composition from all other parts of the plant. In particular, the fucoidan content in sporophylls is several times as high as that in the blade. Alginate preparations isolated from sporophylls and from blade have different proportions of monomers (mannuronic acid and guluronic acid residues) and different molecular masses. Fucoidan preparations isolated from these parts of the plant differ slightly in the sulfate content. Their specific feature is a rather high galactose content comparable with the content of fucose. The sporophylls of A. fistulosa may be regarded as a rich source for practical isolation of fucoidan. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1245–1249, May, 2005.     

Saturated nitrogen-containing heterocycles. VIII. Synthesis and properties of some substituted pyrrolidylalkanols

Phenyl-substituted pyrrolidylalkanols were synthesized by hydrogenation of the corresponding furan amines in acidic aqueous solution in the presence of nickel on diatomaceous earth. Terephthalates, carbamates, and other pyrrolidylalkanol derivatives were obtained. The ability of (2-pyrrolidyl)-3-alkanols to form an intramolecular hydrogen bond was studied by IR spectroscopy.See [1] for communication VII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 186–190, February, 1976.