Reactions of 1,2-dihaloethanes with chalcogenide anions

Reactions of 1,2-dihaloethanes with chalcogenide anions generated from elemental chalcogens and dimethylchalcogens were performed in the hydrazine hydrate-KOH system. The use of anions Se _x ^2? and Te _x ^2? (x = 1?4) resulted in ethylene evolution and chalcogen regeneration (or in increased x value in an anion). Oligomers of Thiokol type formed only in the reaction of the 1,2-dichloroethane with a mixture of potassium disulfide and diselenide. The reductive cleavage of oligomers obtained in the hydrazine hydrate-KOH system followed by methylation led to the formation of 1,2-bis(methylthio)ethane, 1-methylseleno-2-methylthioethane, and 1,2-bis(methylseleno)ethane. The features of substitution with chalcogenide anions in vicinal dihalides are discussed. Mass spectra of compounds obtained were measured and analyzed.     

Cyclosilethynes containing exocyclic cyclopentyl and cyclohexyl groups

The reaction of BrMgCCSiMe₂CCSiMe₂CCSiMe₂CCSiMe₂CCMgBr with chloro(cyclopentyl)(methyl)silane in a large excess of THF gave 1-cyclopentyl-1,4,4,7,7,10,10,13,13-nonamethyl-1,4,7,10, 13-pentasilacyclopentadeca-2,5,8,11,14-pentayne. Similarly, 1,10-di(cyclopentyl)- or 1,6-di(cyclopentylmethyl)-1,4,4,7,7,10,13,13,16,16-decamethyl-1,4,7,10,13,16-hexasilacyclooctadeca-2,5,8,11,14,17-hexaynes were synthesized from BrMgCCSiMe₂CCSiMe₂CCMgBr and dichloro(cyclopentyl)methylsilane or dichloro(cyclopentylmethyl)(methyl)silane. Condensation of Me₂Si(CCMgBr)₂ with dichloro(cyclohexyl)-methylsilane afforded 1,7-di(cyclohexyl)-1,4,4,7,10,10-hexamethyl-1,4,7,10-tetrasilacyclododeca-2,5,8,11-tetrayne.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1282–1284.Original Russian Text Copyright © 2004 by O. Yarosh, Zhilitskaya, N. Yarosh, Albanov, Klyba, Voronkov.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis and paramagnetic properties of polytelluride oligomers

Organotellurium oligomers with different lengths of the telluride fragments and hydrocarbon chains were synthesized by reactions of tellurium with organic dihalogen derivatives in the system hydrazine hydrate-KOH. Oligomers containing two and three contiguous tellurium atoms in the solid state give rise to strong ESR signals with a g value of 2.005–2.030 and a line width of 180–290 Oe. The possibility for formation of tellurium-centered radicals is discussed. Nitrosodurene as radical scavenger in chloroform solution trapped neither primary radical species nor radical products derived therefrom.     

First example of the synthesis of N-vinylpyrrole from methoxy- allene and methoxyethyl isothio- cyanate: unprecedented elimination of methanol from a β-substituted methyl ethyl ether

Using as example 3-methoxy-1-(2-methoxyethyl)-2-methylsulfanylpyrrole, obtained in one preparative stage from α-lithiated methoxyallene and 2-methoxyethyl isothiocyanate, a facile cleavage of a C–O bond in the N-(2-methoxyethyl) substituent by the t-BuOK–DMSO system has been discovered, opening access to a new class of N-vinylpyrroles (through β-elimination of methanol).     

1,2-Ditellurolane: A new synthetic method, structure and chemical reactions

A simple method for the synthesis of 1,2-ditellurolane is proposed, based on the reaction of elemental tellurium with 1,3-dihalopropane in a system of hydrazine hydrate and alkali followed by the effect of organic solvent on the first formed poly(trimethyleneditellurides). The products of the oxidation and reduction of 1,2-ditellurolane were characterized and its spectral characteristics were analyzed. Dedicated To Academician Of The Russian Academy Of Science Mikhail Grigor’evich Voronkov on his 85^th Birthday. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1705–1713, November 2006.     

Mass spectra of new heterocycles: XVI. Electron impact study of alkyl 5-aminothiophene-2-carboxylates

Electron impact mass spectra of alkyl 4-alkoxy-5-amino-3-methylthiophene-2-carboxylates were studied for the first time. These compounds, except for 4-(1-ethoxyethoxy) and 4-(ferrocenylmethoxy) derivatives, give rise to a stable molecular ion whose decomposition follows three pathways. The main fragmentation pathway of the molecular ion is elimination of alkyl radical from the 4-alkoxy group, the second pathway involves expulsion of alkoxy group from the ester moiety, and the third pathway is decomposition of the thiophene ring. The molecular ions of 4-(1-ethoxyethoxy)thiophenes decompose mainly via elimination of ethyl vinyl ether molecule with formation of [M–VinOEt]⁺ · odd-electron ion, and fragmentation of the latter follows general pathways. In the mass spectra of 4-(ferrocenylmethoxy)thiophenes the most abundant are ferrocenylmethyl ion with m/z 199 (I _rel 100%) and fragment ions derived therefrom.