Synthesis of new chiral mono-, di-, tri-, and tetraalkylglycolurils

Two general procedures were developed for the synthesis of chiral N-mono-, N, N′-di-, N, N′ N″-tri-, and N, N′, N″, N′″-tetraalkylglycolurils based on the reactions of 4,5-dihydroxy-imidazolidin-2-ones or glyoxal with one or two moles of alkylureas, respectively, by acid catalysis. The reactions of N-monoalkyl- and N, N′-dialkylureas with glyoxal proceed regioselectively. The mechanism of these reactions was suggested and partly confirmed by quantum-chemical calculations and experimental data. The enantiomeric separation of some chiral glycolurils by chiral-phase HPLC was carried out for the first time.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 680–692, March, 2005.     

First example of the Chan—Lam—Evans N-arylation of bispidines

Russian Chemical Bulletin - The N-arylation of N-Boc-bispidine with arylboronic acids was accomplished under the copper-catalyzed Chan—Lam—Evans reaction conditions. The reaction...     

Furazan-containing bromoarenes in the Suzuki-Miyaura reaction

The palladium-catalyzed cross-coupling reactions of 3-[bromo(het)aryl]furazans and bromobenzofurazans with arylboronic acids afford target biaryls in good yields. 3-Bromo-4-phenylfurazan containing a bromine atom in the furazan ring undergoes decomposition under the reaction conditions.     

Discovery of cationic domino reaction under the NMR experiment conditions: diastereoselective dimerization of 2-arylmethylideneindolin-3-ones to pentacyclic 3-hydroxyindolenine system

NMR spectroscopy (1D and 2D) showed that the protonation of the capto-dative heterocyclic α-amino enones, viz., (Z)-2-arylmethylideneindolin-3-ones, with strong acids led to stable (aryl)(3-hydroxyindol-2-yl)methyl cations. These substrates in trifluoroacetic acid underwent cationic domino reaction, which resulted in polynuclear pyrido[1,2-a: 5,6-b′]-[1,2′]biindoles.     

Synthesis and structure of 2,2′-diaminodiphenylditelluride bis-imines

Bis-imines of 2,2′-diaminodiphenylditelluride and 2-tosylamino (9a) and 2-hydroxybenzaldehyde (9b) were prepared and studied by X-ray diffraction, heteronuclear (¹H, ¹³C, ¹⁵N, and ¹²⁵Te) magnetic resonance, and quantum chemical calculations (Pbe1pbe/DGDZVP). According to the X-ray diffraction data, compound 9b in the crystal phase has nonsymmetrical structure: one of the tellurium atoms forms hypervalent bonding with the adjacent oxygen atom, while the second one is not involved in such interaction. The NMR study showed the symmetric molecular structure of imines 9a,b in DMSO-d₆ with the tellurium atoms interacting hypervalently with the C=N nitrogen atoms.     

ACID SODIUM SALT OF 1H-PYRAZOLE-3,4,5- TRICARBOXYLIC ACID: SYNTHESIS,CRYSTAL STRUCTURE AND FEATURES OF INTRAMOLECULAR BONDS

Journal of Structural Chemistry - The oxidation reaction of 3,3′,5,5′-tetramethyl-1H,1′H-4,4′-bipyrazole in the HNO3–Fe3+ system unexpectedly resulted in the formation...     

Hydrates and ammonium salts of 4-nitrobenzenesulfonic acid: supramolecular organization and its relation to proton conductivity

Structural features, the crystal packing, and the proton conductivity of a series of hydrates and ammonium salts of 4-nitrobenzenesulfonic acid were studied. It was shown that infinite cation associates containing the onium moiety are responsible for a substantial increase in the proton conductivity. The nature of the disorder in a series of crystals was investigated by performing X-ray diffraction studies at different temperatures. A new type of structural synthons, viz., anion-anion dimers stabilized by the SO₃ ⁻…NO₂ interaction, was found and characterized and the role of solvent water molecules was elucidated based on high-resolution X-ray diffraction data. The water molecules serve mainly as channels for charge transfer from the cation to the anion with retention of the electroneutrality.     

Unprecedented conversion of triethylamine and disulfur dichloride into a thienopentathiepin and a heptathiocane

[reaction: see text] In a remarkable cascade reaction, triethylamine is converted into the thienopentathiepin 2a and the heptathiocane 3a by a preequilibrated solution of disulfur dichloride and DABCO in chloroform.     

Diastereoselective synthesis of polyfunctional compounds based on the tandem sequence of threeAd E reactions using cyclic vinyl ethers as first alkene components

The reaction of the bicyclic thiophanium ions salts, generated by the sequential interaction ofp-TolSCI with dihydropyran or 1-methoxycycloalkene and then with an acyclic alkyl vinyl ether in the presence of a Lewis acid and with silicon- or tin-capped π-donors, proceeds with high diastereoselectivity at all newly created chiral centers. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 82–94, January, 2000.