Base-Induced Selective Ring Opening of 1-Arylbenzo[b]thiophenium Salts

Kitamura, Tsugio; Takachi, Tatsuya; Soda, S.; Kawasato, Hironobu; Taniguchi, Hiroshi

doi:10.1246/cl.1992.1357

Cited by 10 publications

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“…Because 1-alkyl-1-benzothiophenium salts are much higher in chemical reactivity than the corresponding 1-phenyl-1-benzothiophenium salts, the cycloadducts, 1-phenyl-2,3-dihydro-1-benzothiophenium salts, are expected to be more reactive. Previously, we reported that 1-aryl-1-benzothiophenium salts undergo the ring-opening reaction upon treatment with methoxide anion . To compare the reactivity of the cycloadducts with that of 1-phenyl-1-benzothiophenium salts, we examined the reaction of the cycloadducts with sodium methoxide in methanol.…”

Section: Resultsmentioning

confidence: 99%

Novel [4 + 2]-Cycloaddition of 1-Phenyl-1-benzothiophenium Salts with Dienes. Experimental Evidence for a Lack of Aromaticity in the Thiophene Ring

2003

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The [4 + 2]-cycloaddition reaction of 1-phenyl-1-benzothiophenium triflates has been conducted for the first time. [4 + 2]-Cycloaddition with dienes such as cyclopentadiene and 1,3-diphenylisobenzofuran occurs successfully to give cycloadducts. This result indicates that the C=C bond of the thiophene ring acts as a 2pi electron component in the cycloaddition reaction. Cycloadducts were formed in high yields with high stereoselectivity. However, the cycloaddition with other less reactive dienes such as 2,3-dimethyl-1,3-butadiene did not take place. The structure and stereochemistry of cycloadduct 2a were analyzed by NMR techniques. Furthermore, reaction of the cycloadducts with sodium methoxide in methanol gave the ring-opened products in high yields.

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Section: Resultsmentioning

confidence: 99%

Novel [4 + 2]-Cycloaddition of 1-Phenyl-1-benzothiophenium Salts with Dienes. Experimental Evidence for a Lack of Aromaticity in the Thiophene Ring

2003

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ChemInform Abstract: Base‐Induced Selective Ring Opening of 1‐Arylbenzo(b)thiophenium Salts.

et al. 1993

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Organic Transformation of Benzothiophenes by C−S Bond Cleavage Beyond Reductive Desulfurization

Huang

2021

Eur J Org Chem

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As the analogues of indole bicyclic system, benzothiophenes are often overlooked in organic transformation, and synthetic methods developed mostly rely on the acidic protons at C2 or C3 position, known as CÀ H functionalization. Complementary to the structural modification of benzothiophenes, CÀ S bond cleavage can realize the skeleton reconstruction. Reduction of benzothiophenes always involves the CÀ S bond cleavage, especially in the hydrodesulfurization (HDS) of petroleum products. Beyond reductive desulfurization, although CÀ S bond cleavage of benzothiophenes has been achieved by diverse methodologies, there is no systematic review on such topic. Herein, transformation of benzothiophenes via CÀ S bond cleavage in organic synthesis will be presented along with briefly delineated mechanism.

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Base-Induced Selective Ring Opening of 1-Arylbenzo[b]thiophenium Salts

Abstract: Reactions of 1-arylbenzo[b]thiophenium salts with methoxide anion in methanol caused the fission of the S+-C(2) bond of the thiophenium ring to produce o-(phenylthio)phenyl-substituted methoxyethenes, allenes, or alkynes.

Cited by 10 publications

References 3 publications

Novel [4 + 2]-Cycloaddition of 1-Phenyl-1-benzothiophenium Salts with Dienes. Experimental Evidence for a Lack of Aromaticity in the Thiophene Ring

Novel [4 + 2]-Cycloaddition of 1-Phenyl-1-benzothiophenium Salts with Dienes. Experimental Evidence for a Lack of Aromaticity in the Thiophene Ring

ChemInform Abstract: Base‐Induced Selective Ring Opening of 1‐Arylbenzo(b)thiophenium Salts.

Organic Transformation of Benzothiophenes by C−S Bond Cleavage Beyond Reductive Desulfurization

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