V. K. Bel'skii

Tetrazoles: XLIV. Synthesis and Chemical Properties of 5-Substituted 2-Triphenylmethyltetrazoles

Tritylation of tetrazole and its 5-substituted derivatives with triphenylmethyl chloride under conditions of phase-transfer catalysis regioselectively yields the corresponding 5-substituted 2-trityltetrazoles which can be used to protect NÄH bonds in nitrogen-containing heterocycles and OÄH bonds in primary alcohols. Thermolysis of 2-trityltetrazoles in benzonitrile leads to 3,6-disubstituted 1,2,4,5-tetrazines. Thermal transformation of the same compounds in dodecane follows a radically different mechanism, resulting in formation of difficultly accessible 8,8-diphenylheptafulvenes. The structure of the latter was proved by X-ray analysis.

Molecular Structure and Spectral Properties of Methionine Sulfone, Product of Methionine Oxidation

Methionine sulfone , a product of complete oxidation of sulfur in methionine amino acid, was subjectedto X-ray diffraction study on a single crystal. According to X-ray diffraction data the packing of methioninesulfone molecules in a crystal is characteristically strongly anisotropic and it is stabilized by a network of intermolecularhydrogen bonds.

Complexes of 2,3-Dihydroxypyridine with Bivalent Metals. Crystal Structure of 2,3-Dihydroxypyridine

Crystal structure of 2,3-dihydroxypyridine (H2L) is determined. Mn(HL)Cl · H2O, Co(HL)Cl · 2H2O, Cu(HL)Cl, Ni(HL)OH · H2O, and Zn(HL)OH · H2O complexes are synthesized by reacting Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) chlorides with H2L in ethanol solutions and identified. In these complexes, 2,3-dihydroxypyridine is involved in coordination as a monoanion. Spectral parameters of neutral and anionic forms of a ligand are determined and the acidity and complex formation constants are calculated. The compositions of complexes are established.

Dioxaphosphacyclanes. Synthesis and Chemical Properties

Abstract1,5- and 2,7-dihydroxynaphthalenes were reacted with P(III) amides to obtain naphthocyclophanes. The structures and chemical properties of the products were studied.

2,6- and 1,6-Dihydroxynaphthalenes in the Synthesis of Phosphacyclophanes

Peculiar phosphacyclophanes were prepared from symmetrical 2,6- and unsymmetrical 1,6-dihydroxynaphthalenes. The position of the hydroxy groups in dihydroxynaphthalenes considerably affects their reactivity, the structure of the phosphacyclophanes obtained, and also the disproportionation of bisphosphoramidites. Oxo and thio derivatives of these phosphoramidites as well as their molybdenum complexes were prepared.

HIGHER 1,3,2-DIAZAPHOSPHOCYCLANES. V. 4,5; 6,7-DIBENZO-1,3,2-DIAZAPHOSPHEPANES

Abstract The synthesis, structure and chemical features of a new class of tricyclic phosphorus-containing heterocycles are reported. Special attention is paid to the dynamics of molecules and their tendency to enter into elimination reactions. A possibility to synthesize relatively stable dibenzo-1,3,2-diazaphosphepene containing a two-coordinated phosphorus atom is considered.

Heterocyclic Thiones and Their Analogs in 1,3-Dipolar Cycloaddition Reactions: II. Reactions of Benzothiazole-2-thione with Nitrilimines

Benzothiazole-2-thione reacted with C,N-disubstituted nitrilimines to give the corresponding bis-[2-(1,3,4-thiadiazol-2-ylideneamino)phenyl] disulfides. In some cases, α-(1,3-benzothiazol-2-ylsulfanyl)-(α-R)-alkanone arylhydrazones were formed as by-products. The structure of the isolated compounds was proved by X-ray analysis.

Complexes of d and f Metals with 2-Methyl-3-hydroxy(amino)pyrido[1,2-a]pyrimidine-4-one. Crystal Structure of 2-Methyl-3-hydroxypyrido[1,2-a]pyrimidine-4-one

Six complexes of scandium(III), lanthanum(III), praseodymium(III), and copper(II) chlorides with 2-methyl-3-hydroxypyrido[1,2-a]pyrimidine-4-one (HL1) and 2-methyl-3-aminopyrido[1,2-a]pyrimidine-4-one (L2), as well as hydrochloride and hydronitrate L2, were isolated. The crystal and molecular structures of HL1 were determined. HL1 in CCl4 solution was shown (IR data) to occur as two forms, namely, neutral and zwitterionic forms. The structures for the complexes isolated were proposed.

Higher 1,3,2-Diazaphosphacyclanes: V. Synthesis, Structure, and Chemical Features of 4,5;7,8-Dibenzo-1,3,2-diazaphosphocanes

A procedure was developed for preparing 4,5;7,8-dibenzo-1,3,2-diazaphosphocanes containing trivalent and pentavalent phosphorus atoms. The structure of the compounds was determined by NMR spectroscopy and single crystal X-ray diffraction. The conformational transitions of the diazaphosphocanes in solution were analyzed. First data were obtained on transformations of the obtained eight-membered heterocycles.

Heterocyclic Thiones and Their Analogs in Reactions of 1,3-Dipolar Cycloaddition: III. Reaction of Benzothiazole-2-thione with a Double Excess of Nitrilimine

Main products of reaction between benzothiazole-2-thione and a double excess of nitrilimine are substituted 1-aryl-1-(1,3-benzothiazol-2-yl)-2-(2,3-dihydro-1,3,4-thiadiazol-2-yl)hydrazines. In the first step presumably forms a spiro compound via 1,3-dipolar cycloaddition of nitrilimine molecule to the C=S bond of the benzothiazolethione. The second nitrilimine molecule adds to the new C=S bond of the intermediate product arising by the rupture of CS bond in the thiadiazole ring of the spiro compound.