33369-81-2Relevant academic research and scientific papers
Rhodium-Catalyzed Isomerization and Alkyne Exchange Reactions of 1,4-Dithiins via the 1,2-Ethenedithiolato Rhodium Complex
Arisawa, Mieko,Sawahata, Kyosuke,Ichikawa, Takuya,Yamaguchi, Masahiko
, p. 3174 - 3180 (2018/09/25)
Rhodium-catalyzed isomerization and alkyne exchange reactions of 1,4-dithiines occurred by cleavage of two C-S bonds. The 2,5- and 2,6-disubstituted 1,4-dithiins underwent isomerization reactions in toluene at 110 °C, providing equilibrium mixtures of isomers. At 150 °C, the reaction of 1,4-dithiins and dimethyl acetylenedicarboxylate gave unsymmetric 2,3-di(methoxycarbonyl)-1,4-dithiins and 2,3-di(methoxycarbonyl)thiophenes, the latter of which were formed by desulfurization of the 1,4-dithiins. A related reaction of the alkyne and a 1,2-dithiete gave a 2,3-di(methoxycarbonyl)thiophene. These reactions are considered to involve 1,2-ethenedithiolato rhodium intermediates.
Preparation of Congested Thiophenes Carrying Bulky Substituents on the 3- and 4-Positions and Their Conversion to the Benzene Derivatives
Nakayama, Juzo,Hasemi, Ryuji,Yoshimura, Koichi,Sugihara, Yoshiaki,Yamaoka, Shoji,Nakamura, Nobuo
, p. 4912 - 4924 (2007/10/03)
Highly congested thiophenes, 3,4-di-tert-butyl-, 3,4-di(1-adamantyl)-, 3,4-dineopentyl-, and 3-(1-adamantyl)-4-tert-butylthiophenes (4a-d), were prepared in satisfactory overall yields by intramolecular reductive coupling of 3-thiapentane-1,5-diones (1a-d) followed by acid-catalyzed dehydration of the resulting thiolane-3,4-diols (2a-d). Experimental procedures of this thiophene synthesis are fully described. Oxidation of the thiophenes 4a-d with m-CPBA gave the corresponding thiophene 1,1-dioxides 13a-d in good yields. The Diels-Alder reactions of 13a-d with phenyl vinyl sulfone gave o-di-tert-butyl-, o-di(1-adamantyl)-, o-dineopentyl-, and o-(1-adamantyl)-tert-butylbenzenes (17a-d) directly in high yields with loss of benzenesulfinic acid and sulfur dioxide. The dioxides 13a-d also underwent Diels-Alder reactions with alkynic dienophiles to give the corresponding benzene derivatives carrying two bulky substituents on adjacent positions. Pyridazines 25b,c, carrying bulky substituents on the 4- and 5-positions, were also synthesized through Diels-Alder reaction of 13b,c with PTAD. Dimethylation of the 2- and 5-positions of 13a-d was attained by treatment with strong bases followed by reactions with methyl iodide. The resulting tetrasubstituted thiophene 1,1-dioxides 14a-d reacted with DMAD to give highly congested hexasubstituted benzene derivatives 15a-d in good yields. Finally, structural features of the congested molecules are discussed on the basis of NMR analyses. Typically, the barriers to rotation (ΔH?) about the benzene to the bulky substituents of 15a,c,d were determined to be 8.59, 15.3, and 7.40 kcal/mol, respectively, by NMR total line-shape analysis.
A Convenient Synthesis of 1,2-Dithietes and 1,2-Dithioxo Compounds Stabilized by Buttressing and Resonance Effects, Respectively, by Sulfuration of Alkynes with Elemental Sulfur
Choi, Keun Soo,Akiyama, Isao,Hoshino, Masamatsu,Nakayama, Juzo
, p. 623 - 629 (2007/10/02)
Sulfuration of a series of alkynes by elemental sulfur was investigated.Alkynes carrying highly bulky substituents, 2,2,5,5-tetramethyl-3-hexyne (6a), 1,2-di-(1-adamantyl)ethyne (6b), 3,3-dimethyl-1-phenyl-1-butyne (6c), and 1-(1-adamantyl)-2-phenylethyne (6d), reacted with sulfur to give the corresponding stable 1,2-dithietes 7a-d in 46-65percent yields.Less hindered alkynes reacted with sulfur to afford 1,4-dithiins and thiophenes as the final products which were derived from the initial products, 1,2-dithietes, via their tautomerization to the corresponding 1,2-dithioxo compounds, while extremely congested alkynes failed to react with sulfur even under forcing conditions.On the other hand, ynamines, a typical electron-rich alkyne, 1-diethylamino-2-phenylthioethyne (6o), 1-diethylamino-2-phenylselenoethyne (6p), and tetraethylethynediamine (6q) were sulfurated under milder conditions to afford resonance-stabilized 1,2-dithioxo compounds 19o-q as the principal products.Mechanism of the formation of 1,2-dithietes, 1,2-dithioxo compounds, and other products is discussed.
SYNTHESIS AND ELECTROPHILIC TRICHLOROMETHYLATION OF 2,4-DIALKYLTHIOPHENES. SOME TRANSFORMATIONS OF 2,4-DI-tert-BUTYL-5-(TRICHLOROMETHYL)THIOPHENE
Belen'kii, L. I.,Gromova, G. P.,Krayushkin, M. M.
, p. 883 - 888 (2007/10/02)
The disproportionation products of the C-protonation of 5-tert-butyl-2-methyl- and 2-ethylthiophene first give 4-tert-butyl-2-methyl- and 2-ethylthiophene. We studied the electrophilic trichloromethylation of a series of 2,4-dialkyl thiophenes and showed that the reaction goes smoothly only for the most sterically hindered 2,4-di-tert-butyl-thiophene. We studied the reaction of 2,4-di-tert-butyl-5-(trichloromethyl)thiophene with some O- and N-nucleophiles.
SYNTHESIS AND REACTIONS OF 3,4-DI-t-BUTYLTHIOPHENE
Nakayama, Juzo,Yamaoka, Shoji,Hoshino, Masamatsu
, p. 1161 - 1164 (2007/10/02)
3,4-Di-t-butylthiophene (1) was surprisingly easily synthesized from readily accessible bis(2-t-butyl-2-oxoethyl) sulfide (2).Reactions of 1 with a variety of electrophiles were examined.
NITRILE OXIDES OF THE THIOPHENE SERIES: INFLUENCE OF STERIC FACTORS ON STABILITY AND REACTIVITY IN REACTIONS OF 1,3-DIPOLAR CYCLOADDITION
Krayushkin, M. M.,Loktionov, A. A.,Belen'kii, L. I.
, p. 850 - 856 (2007/10/02)
The synthesis of a series of di- and trialkyl-substituted thiophenecarbonitrile oxides is described.Their addition to styrene is studied together with the quantitative evaluation of the influence of different alkyl groups on the rate of the 1,3-dipolar cy
STABLE HETEROARENIUM IONS - VIII SOME TRANSFORMATIONS OF ALKYLTHIOPHENIUM IONS AND NEW SYNTHESIS OF 2-t-BUTYLTHIOPHENE
Belen'kii, L. I.,Yakubov, A. P.
, p. 2471 - 2477 (2007/10/02)
The ratio of isomeric ?-complexes formed from thiophene, t-butyl chloride and AlCl3 was found to be changed while keeping at room temperature whitin 1-2 days.This allows to obtain after deprotonation 2-t-butylthiophene containing only 3percent of 3-isomer.Transformations of ?-complexes formed by protonation of individual 2- and 3-t-butylthiophenes in the presence of AlCl3 have been studied and there was found that isomerization and deprotonation took place during their storage resulting in mixtures of 2- and 3-t-butylthiophenes (the ratio 97:3) which contained considerable quantities of 2,4-di-t-butylthiophene.Deprotonation of t-butylthiophenium ions in the presence of acetone leads to the formation of respective t-butylsubstituted dimethyldithienylmethanes.
