V. K. Zav'yalova

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 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 reactions of thiophene sulfides. 38. Some reactions of 5-substituted thieno[3,2-d]isothiazoles

Conclusions1.Bromination of 5-alkyl(methoxy)thieno[3,2-d]isothiazoles with bromine or N-bromosuccinimide affords high yields of 4-bromo-5-alkyl(methoxy)thieno-[3,2-d]isothiazoles.2.In the reaction of butyllithium with 5-substituted thieno[3,2-d]isothiazoles, the principal reaction is cleavage of the isothiazole ring to give the corresponding 2-butylthio-3-thiophenealdehydes.

Synthesis and transformations of sulfides in the thiophene series 35. Synthesis of certain polyfunctional and condensed compounds derived from substituted acetals in the thiophene series

Conclusions1.Metallation of diacetals of 5-substituted-2-alkylthio-3-thiophenecarboxaldehydes with butyllithium in ether proceeds at the freeβ-position of the thiophene ring, so that different polyfunctional derivatives of thiophene can be synthesized.2.By the action of sodium in liquid ammonia on 5-methoxy-2-methylthio-3-thiophenecarboxaldehyde diethylacetal, and subsequent treatment with water, 5-methylthieno [3,2-d]isothiazole is formed.3.Certain intracoordination compounds of Co(II), Ni(II), and Zn were obtained which include the thiophene ring substituted in the α-position with a methoxy group.

Synthesis and transformation of sulfides of the thiophene series. 34. Quantum-chemical studies of the specificity of electrophilic attack and isomerization under C-protonation conditions in the alkylmercaptothiophene series

Abstract2-Methoxy-5-methylthiothiophene, 2,5-bis(methylthio)thiophene, and all of their possible C-protonated forms (σ complexes) were subjected to calculations by the self-consistent-field (SCF) MO LCAO method within the CNDO/2 (complete neglect of differential overlap/2) valence approximation. The results obtained were used to explain the peculiarities of the behavior of these compounds in electrophilic-substitution reactions (Vilsmeier formylation and acetylation). It is shown that the most preferred sites of electrophilic attack in both compounds are the 3 and 5 positions, while the least active site is the 2 position in 2-methoxy-5-methylthiophene, as a result of which one should not observe either migration or splitting out of an OCH3 group, in agreement with the available experimental data. The energetics of the secondary transformations of the σ complexes formed in the reaction, viz., isomerization and elimination of the SCH3+ group, were estimated.

15N and13C NMR spectral study of the Z, E isomerism of thiophene aldoximes

Chemical shifts and coupling constants were determined in the15N and13C NMR spectra of thiophene aldoximes with natural isotope content. The effects of Z, E isomerism on the spectral parameters were determined. The2J15N.H and1J13C.H coupling constants in the CH=NOH fragment are characteristic.

Synthesis and reactions of thiophene sulfides. Communication 40. An unusual reaction of 2,5-bis(methylthio)-3,4-bis(o-hydroxyphenyliminomethyl)thiophene

ConclusionsIn polar solvents (ethanol and chloroform), 2,5-bis(methylthio)-3,4-bis-(o-hydroxyphenyliminomethyl) thiophene undergoes intramolecular rearrangement to 2,5-bis(methylthio)-3-(2′-benzoxazolyl)-4-(o-hydroxyphenylaminomethyl) thiophene.

Synthesis and transformations of sulfides of the thiophene series. 39. Synthesis and pharmacological properties of some 2,5-disubstituted 3-thienylalkylamines

A number of isomeric 3-thienylalkylamines containing methylthio and methoxy groups in the α positions of the thiophene ring have been synthesized. It has been shown that they possess a weak activity of the stimulating and antidepressant type.

Synthesis and transformations of sulfides in thiophene series. Communication 37. synthesis and properties of 2-methoxy-5-methylthiophenes, substituted by bromine or alkylthio- and alkylsulfonyl groups

Conclusions1.3-Bromo-, 3-alkylthio-, 3-alkylsulfonyl- and 3-chloroalkylsulfonylthiophenes with methoxy and alkylthio (alkylsulfonyl) groups In the α-positions of the thiophene ring were prepared.2.During the bromination of 2-methoxy-(5-methylthio)thiophene by N-bromosuccinimide, the bromine atom preferentially enters the Β-position in the thiophene ring, adjacent to the methoxy group.