3,4-Di-tert-butylthiophene 1,1-dioxide, a convenient precursor of o-Di-tert-butylbenzene and its derivatives

Nakayama, Juzo; Yamaoka, S.; Nakanishi, Tomoko.; Hoshino, Minoru

doi:10.1021/ja00227a069

Cited by 53 publications

(10 citation statements)

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“…The satisfactory yields of 13a − d attained above should be ascribed to steric hindrance, which prevents the thiophene 1-oxides from selfdimerization . Nevertheless, the thiophene 1,1-dioxides 13a − d can act as 4π-components on strong dienophiles to give Diels−Alder adducts in high yields, thus providing a convenient synthesis of highly congested benzene derivatives and other compounds as discussed below. , Lithiation of the α-positions of the thiophene 4a does not take place even by action of strong bases such as alkyllithiums and lithium diisopropylamide (LDA) because of steric hindrance 4a. However, conversion of thiophenes 4a − d to the corresponding thiophene 1,1-dioxides 13a − d makes the α-hydrogens acidic enough to be lithiated.…”

Section: Conversion Of Thiophenes To Congested Benzene and Pyridazine...mentioning

confidence: 98%

Preparation of Congested Thiophenes Carrying Bulky Substituents on the 3- and 4-Positions and Their Conversion to the Benzene Derivatives

et al. 1998

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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.

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Section: Conversion Of Thiophenes To Congested Benzene and Pyridazine...mentioning

confidence: 98%

Preparation of Congested Thiophenes Carrying Bulky Substituents on the 3- and 4-Positions and Their Conversion to the Benzene Derivatives

et al. 1998

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“…The first DA cycloaddition with SO 2 extrusion, 3,4-di-tert-butyl-1,1-dioxothiophene as a diene, mono-, and disubstituted acetylenes involved in the syntheses of 1,2-di-tert-butyl benzene derivatives ( Scheme 261 ) was described by Nakayama in 1988 [ 316 ].…”

Section: 11- Dioxothiophene For the Benzene And Naphthalene Ring Formationmentioning

confidence: 99%

“… Syntheses of o -di-tert-butylbenzene derivatives [ 316 ]. Reagents and conditions: a = appropriate solvent, up tu 230 °C, up to 45 h; R 1 ,R 2 = CO 2 Me, CO 2 Me (Y = 100%); H, CO 2 Me (Y = 72%); H, COMe (Y = 84%); H, Ph (Y = 92%); H, n -Bu (Y = 32%); PhS, NEt 2 (Y = 34%), and others.…”

Section: Figure and Schemesmentioning

confidence: 99%

Diels–Alder Cycloaddition with CO, CO2, SO2, or N2 Extrusion: A Powerful Tool for Material Chemistry

et al. 2021

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Phenyl, naphthyl, polyarylphenyl, coronene, and other aromatic and polyaromatic moieties primarily influence the final materials’ properties. One of the synthetic tools used to implement (hetero)aromatic moieties into final structures is Diels–Alder cycloaddition (DAC), typically combined with Scholl dehydrocondensation. Substituted 2-pyranones, 1,1-dioxothiophenes, and, especially, 1,3-cyclopentadienones are valuable substrates for [4 + 2] cycloaddition, leading to multisubstituted derivatives of benzene, naphthalene, and other aromatics. Cycloadditions of dienes can be carried out with extrusion of carbon dioxide, carbon oxide, or sulphur dioxide. When pyranones, dioxothiophenes, or cyclopentadienones and DA cycloaddition are aided with acetylenes including masked ones, conjugated or isolated diynes, or polyynes and arynes, aromatic systems are obtained. This review covers the development and the current state of knowledge regarding thermal DA cycloaddition of dienes mentioned above and dienophiles leading to (hetero)aromatics via CO, CO2, or SO2 extrusion. Particular attention was paid to the role that introduced aromatic moieties play in designing molecular structures with expected properties. Undoubtedly, the DAC variants described in this review, combined with other modern synthetic tools, constitute a convenient and efficient way of obtaining functionalized nanomaterials, continually showing the potential to impact materials sciences and new technologies in the nearest future.

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“…[1,2] Although applications of thiophenes in Diels-Alder reactions have been described, [3] am ore common way to use thiophenes as dienes is after oxidation to the corresponding thiopheneS ,S-dioxides. [4] Although non-stabilized thiophene dioxides easily undergod imerizationr eactions, [5,6] their stabilized analogues are used as dienes in cycloadditions with alkenes [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and alkynes, [22][23][24][25][26][27] mostly under drastic reactionc onditions. However,t he oxidation of thiophenes can be stoppeda tt he sulfoxide stage and the resulting thiopheneS -oxides undergo Diels-Alder reactions under much milder conditions.…”

Section: Introductionmentioning

confidence: 99%

Towards the Design of Optically Active Thiophene S‐Oxides using Quantum Chemistry

Verlinden

Woller

Proft

et al. 2019

Chemistry A European J

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The importance of axially chiral biaryls has risen steeply in the recent decades. This structural motif proved to be successful in catalytic asymmetric synthesis and the configuration of the biaryl axis is decisive for the biological activity. A new approach for the atroposelective synthesis of biaryls would be through a cycloaddition between an enantiopure phenyl‐substituted thiophene S‐oxide and an alkyne. Importantly, the chiral center of the thiophene S‐oxide needs to be stable enough to avoid pyramidal inversion during the cycloaddition. Considering that the racemization of thiophene monoxides has been scarcely investigated so far, we perform a thorough quantum chemical study on the inversion barriers of a large number of chiral thiophene S‐oxide derivatives. Our main goal is to identify substitution patterns leading to stable atropisomers at room temperature. Appealingly, the role of stereoelectronic effects and the position of the substituents as well as the importance of aromaticity on the pyramidal inversion barrier are elucidated for the first time.

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3,4-Di-tert-butylthiophene 1,1-dioxide, a convenient precursor of o-Di-tert-butylbenzene and its derivatives

Cited by 53 publications

References 2 publications

Preparation of Congested Thiophenes Carrying Bulky Substituents on the 3- and 4-Positions and Their Conversion to the Benzene Derivatives

Preparation of Congested Thiophenes Carrying Bulky Substituents on the 3- and 4-Positions and Their Conversion to the Benzene Derivatives

Diels–Alder Cycloaddition with CO, CO2, SO2, or N2 Extrusion: A Powerful Tool for Material Chemistry

Towards the Design of Optically Active Thiophene S‐Oxides using Quantum Chemistry

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