M. A. Kalik

Synthesis and transformations of sulfides of the thiophene series. 33. Structures of the products of formylation of 2-methoxy-5-methylthiothiophene

Isomeric alkoxy (alkylthio) formylthiophenes were synthesized from 4-iodo-2-methoxythiophene, and the structures of the products of Vilsmeier formylation of 2-methoxy-5-methylthiothiophene were confirmed.

Synthesis and several transformations of sulfides of the thiophene series

Several new N-substituted 2,5-bis(mercapto)-3,4-bis(iminomethyl)thiophenes, which are new tetradentate ligands of the thiophene series, were obtained by the reaction of primary amines with the product formed during the successive action of four equivalents of sodium in liquid ammonia and HCl on the tetraethylacetal of 2,5-bis(methylmercapto)-3,4-thiophenedialdehyde.

Chemical behavior of 5-alkoxy-2-alkylthiophenes under the conditions of the vilsmeier reaction

Dealkylation of the methoxy group and formation of N-substituted 5-alkyl-3-aminomethylene-4-thiolen-2-ones occur during the action of substituted formamides and phosphorus oxychloride on 5-methoxy-2-alkylthiophenes on heating at 50–70 deg C. At 20 deg the major reaction products are 5-alkyl-2-methoxy-3-formylthiophenes.

Synthesis and transformations of sulfides of the thiophene series. 32. Synthesis and properties of some (?-ethoxyethyl)-substituted mercapto aldimines and chelates of the thiophene series

Several N-substituted 2-mercapto-5-(β-ethoxyethyl)-3-thenylidenimines and the corresponding chelate compounds with metals, which are readily soluble in organic solvents, were obtained. The synthesized compounds have a slight inhibiting effect on the liquid-phase oxidation of hydrocarbons.

Synthesis and some transformations of thiophene series sulfides

The main products of the reactions of the acetals of 3-ethylmercapto-2-thiophenaldehyde (IIIa) and 4-methylmercapto-3-thiophenaldehyde (IV) with 2 equivalents of sodium are the corresponding mercaptoacetals X, XXII. Reaction of an alkaline solution of mercaptoacetal X with ammonia and HCl at pH ∼ 8 led to the isolation of a compound of composition C10H7NS4 (XIV). The action of 6 equivalents of sodium on the acetals IIIa and IV leads, along with dealkylation of the alkylmercapto group, to reduction of the acetal group to methyl, and formation of 2- and 4-methyl-3-thiophenethiols (V, XVIII) respectively.

Effect of electronic factors on the dimerization and isomerization of substituted nitrile oxides of the thiophene series

Sterically hindered, stable 3-thiophenecarbonitrile oxides containing electron-accepting groups (SO2R, Br) in the 2- or 4-position are converted to substituted 4,5-dithienylfuroxanes when boiled in benzene or toluene, whereas trialkyl-substituted 3-thiophenecarbonitrile oxides isomerize quantitatively to the corresponding isocyanates.

Synthesis of polyfunctional stable nitrile oxides of the thiophene series and their relative reactivities in 1,3-dipolar cycloaddition with styrene

Stable 2-alkylthio- and 2-alkylsulfonylthiophene-3-carbonitrile oxides that contain various functional groups in the 4 and 5 positions of the thiophene ring (Br, OCH3, SCH3, SO2CH3) were synthesized. It is shown that the introduction of electron-acceptor substituents into any position of the ring of thiophene-3-carbonitrile oxides gives rise to acceleration of cycloaddition to styrene. The reactivities of o-substituted thiophene-3-carbonitrile oxides of the thiophene series in 1,3-dipolar cycloaddition reactions are determined by the overall effect of the electronic and steric factors of the substituents.

Synthesis and transformations of sulfides of the thiophene series. 42. Synthesis and properties of some 2-alkylthio(alkylsulfinyl, alkylsulfonyl)thiophene-3-carbonitrile N-oxides

Thiophene-3-carbonitrile N-oxides containing alkylthio, alkylsulfinyl, and alkysulfonyl groups in the 2-position, which readily undergo 1,3-dipolar cycloaddition to the C=C bond (styrene, N-phenylmaleinimide) to give the corresponding 3,5-disubstituted 2-isoxazolines, were obtained.

Synthesis and certain transformations of sulfides of the thiophene series: Communication 19. ?-substituted 2,5-bis(alkylmercapto)thiophenes

The action of methyl iodide on N-(2-mercapto-5-ethyl-3-thienylidene)-α-aminopyridine and its Zn(II), Co(II), and Ni(II) chelates was studied. S-Alkylation and the formation of chelates of the VII and VIII type occur in the case of Zn and Co chelates (III and IV). This fact, together with a consideration of volume and skeleton models of the compounds obtained, makes it possible to arrive at the conclusion that the nitrogen atom of the pyridine ring is coordinated in chelates III and IV (structure C).

Rupture of sulfides of the thiophene series by sodium in liquid ammonia

By tne action of sodium in liquid ammonia, alkylthienyl sulfides are readily dealkylated with formation of the corresponding mercaptans of the thiophene series.