Darzens reaction in the synthesis of 3-(α-chloroalkyl)quinoxalin-2(1H)-ones

A two-stage method was developed for the synthesis of 3-(α-chloroalkyl- and α-chlorophenylalkyl)-quinoxalin-2(1H)-ones proceeding from methyl chloroalkyl- and chlorophenylalkylpyruvates obtained by Darzens reaction from methyl dichloroacetate and appropriate aldehydes in the presence of t-BuOK.     

A novel rearrangement in the system 3-[aryl(chloro)methyl]quinoxalin-2(1H)-one— α-picoline as a simple and efficient route to indolizin-2-ylbenzimidazoles

A reaction of 3-(α-chlorobenzyl)quinoxalin-2(1 H)-one with α-picoline gives 2-(3-phenyl-indolizin-2-yl)benzimidazole as a result of a ring-contracting rearrangement involving the fragment C(2)—C(3)—C(Cl)Ph of the quinoxaline system and the fragment N=CH—Me of the α-picoline system. Possible pathways of this reaction are discussed.     

Synthesis of the Promising Chiral Synthon Isopropyl-4<Emphasis Type="Italic">R</Emphasis>-Methyl-6-Iodohexanoate from L-(-)-Menthol

A synthesis of the promising optically pure synthon isopropyl-4R-methyl-6-iodohexanoate based on ozonolytic transformation of the product of regiospecific dehydratation of L-(-)-menthol, (R)-p-menth-3-ene, into 2,6R-dimethyl-8-hydroxyoctan-3-one was proposed.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 33–36, January–February, 2005.     

Corrosion of electrical alloys based on the Al-Mg-Se system

Effect of calcium and scandium additives on corrosion-electrochemical properties and electrical conductivity of lightly alloyed electrical alloys was studied in order to optimize their composition.     

Properties of N,N-Dimethyl-N′-(2-Hydroxybenzyl)ethylenediamine as a Ligand to Copper(II)

The acid-basic and complexing properties of N,N-dimethyl-N-(2-hydroxybenzyl)ethylenediamine (HL) in aqueous propan-2-ol were characterized by spectrophotometry, pH-metry, and mathematical simulation of equilibria in solutions (T = 25 ± 0.1°C, = 0.1 M KNO₃). Dimer H₂L₂ was found to predominate in solution at c _HL = 0.01 mol/l. Three protonated dimeric (H₃L₂ ⁺, H₄L₂ ²⁺, and H₅L₂ ³⁺), diprotonated monomeric (H₃L²⁺), and triprotonated tetrameric forms (H₇L₄ ³⁺) were detected in the system, depending on pH. At lower ligand concentrations (c _HL = 0.0015 mol/l), the solution contains both dimers and monomers of this compound. The higher dentate number of HL compared to 2-alkylaminomethylphenols allows it to form more number of both mono- and binuclear complexes ([Cu(HL)]²⁺, [Cu(HL)₂]²⁺, [CuL₂], [CuL₂OH]^–, [Cu₂(HL)₂]⁴⁺, and [Cu₂(HL)₂L₂]²⁺), making them more stable.     

Synthesis of 3S-methylundec-1-ylbromide, a key synthon in the synthesis of (S,S,S)-diprionylacetate, from L-(-)-menthol

Three new approaches to the synthesis of 1-bromo-3S-methylundecane, a key synthon in the synthesis of (S,S,S)-diprionylacetate, a sex pheromone of pine sawflies of the genera Diprion and Neodiprion, were proposed based on chemo-and stereoselective transformations of L-(-)-menthol derivatives. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 73–76, January–February, 2006.     

Oxidation of valeraldehyde by chlorine dioxide

The product of the reaction of valeraldehyde with chlorine dioxide was determined, and the solvent effect on the reaction kinetics was studied. The major oxidation product is valeric acid. The reaction rate is described by the second-order equation w = k[RCHO]·[ClO₂]. The rate constants were measured in the 297–328 K interval, and the activation parameters of the reaction were determined.     

New disaccharide blocks for OSW-1 and its analogs

A new disaccharide block for OSW-1 natural steroidal antitumor agent was described. Regioisomeric 2- and 3-O-p-methoxybenzoyl derivatives of phenyl 1-thio-??-d-xylopyranoside and phenyl 2-O-acetyl-1-thio-??-l-arabinopyranoside derivatives blocked at positions 3 and 4 by R₃Si groups were synthesized with a view to use them in the preparation of OSW-1 analogs modified at the disaccharide fragment.