Effective Synthesis of Hard-To-Reach 3,4-Disubstituted Thiophene Derivatives Based on bis(2-chloropropenyl) Sulfide
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Effective synthesis of hard-to-reach 3,4-disubstituted thiophene derivatives based on bis(2-chloropropenyl) sulfide Valentina S. Nikonova1*, Nikolai А. Korchevin1, Tat'yana N. Borodina1, Vladimir I. Smirnov1, Aleksander I. Albanov1, Igor B. Rozentsveig1 1
Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky St., Irkutsk 664033, Russia; е-mail: [email protected]
Translated from Khimiya Geterotsiklicheskikh Soedinenii, 2020, 56(10), 1292–1296
Submitted June 16, 2020 Accepted after revision July 23, 2020
KOH Cl H2C
Cl S
CH2
S
MeCN 20–25°C, 3 h 76% t-BuOK
S
S
MeCN, air –40°C, 3 h 86%
O O
HO MeCN rt, 10 h 94%
O S
An efficient approach for the synthesis of hard-to-reach 3,4-disubstituted thiophene derivatives: 4,5,9,10-tetrahydrothieno[3',4;5,6]cycloocta[1,2-c]thiophene, 1H,4H-thieno[3,4-d][1,2]dioxine, 4-(hydroxymethyl)thiophene-3-carbaldehyde, based on consecutive transformations of bis(2-chloropropenyl) sulfide has been found. Transformations were realized without isolation of the intermediate compounds. The reactivity of 4,5,9,10-tetrahydrothieno[3',4;5,6]cycloocta[1,2-c]thiophene has been studied based on the example of acetylation reaction, and the possibility of obtaining bifunctional derivatives with the participation of both thiophene rings has been shown. The structure of some synthesized compounds has been studied with X-ray diffraction method. Keywords: 4-(hydroxymethyl)thiophene-3-carbaldehyde, 4,5,9,10-tetrahydrothieno[3',4;5,6]cycloocta[1,2-c]thiophene, 1H,4H-thieno[3,4-d][1,2]dioxine, thiophenes.
Substituted thiophene derivatives are widely used in various fields of science and technology, from laboratory synthesis to the production of drugs and modern materials.1–14 β-Substituted thiophenes, in which both α-positions are free, are of particular importance. Such thiophene systems possess many valuable properties and can be easily involved in further transformations.1–10 However, it is known, that due to the specificity of the electron density distribution in the thiophene ring, the direct functionalization of unsubstituted thiophene proceeds predominantly at the α-position; accordingly, the synthesis of β-substituted and especially β,β'-disubstituted thiophene derivatives with free α-positions, as a rule, is a multistep and laborious process,10,15 therefore the development of methods for their preparation is one of the urgent problems of modern organic chemistry. Within the framework of solving this problem, methods for the preparation of β,β'-disubstituted thiophenes based on the cyclization of bis(cumulene) sulfides are of 0009-3122/20/56(10)-1292©2020 Springer Science+Business Media, LLC
particular interest.10,16–23 These sulfides can be considered as sulfur-containing analogs of ene-dicumulenes, in which sulfur atom is in conjugation in the internal position instead of the ethylene fragment. As it is known, ene-dicumulenes, as well as their acetylene-allene tautomers (enediynes, enyne-cumulenes), can undergo cyclization with the f
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