- Pummerer-type Rearrangement on Aromatic Rings: an Unprecedented ipso-Substitution of the Sulfinyl Group of p-Sulfinylphenyl Ethers into Oxygen Functional Groups leading to Protected Dihydroquinone Derivatives
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The treatment of p-(phenylsulfinyl)phenyl ethers 1 with trifluoroacetic anhydride in the presence of styrene selectively caused the direct ipso-substitution of the sulfinyl groups by trifluoroacetoxy groups, giving the protected dihydroquinone derivatives 3 in high to quantitative yields.
- Akai, Shuji,Iio, Kiyosei,Takeda, Yoshifumi,Ueno, Hiroshi,Yokogawa, Kayoko,Kita, Yasuyuki
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- Reactions of Thiiranium and Sulfonium Ions with Alkenes in the Gas Phase
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Ion-molecule reactions between thiiranium ion 11 (m/z 213) and cyclohexene and cis-cyclooctene resulted in the formation of addition products 17a and 17b (m/z 295 and m/z 323, respectively) via an electrophilic addition pathway. Associative π-ligand exchange involving direct transfer of the PhS+ moiety, which has been observed for analogous seleniranium ions in the gas phase, did not occur despite previous solution experiments suggesting it as a valid pathway. DFT calculations at the M06-2X/def2-TZVP level of theory showed high barriers for the exchange reaction, while the addition pathway was more plausible. Further support for this pathway was provided with Hammett plots showing the rate of reaction to increase as the benzylic position of thiiranium ion derivatives became more electrophilic (ρ = +1.69; R2 = 0.974). The more reactive isomeric sulfonium ion 22 was discounted as being responsible for the observed reactivity with infrared spectroscopy and DFT calculations suggesting little possibility for isomerization. To further explore the differences in reactivity, thiiranium ion 25 and sulfonium ion 27 were formed independently, with the latter ion reacting over 260 times faster toward cis-cyclooctene than the thiiranium ion rationalized by calculations suggesting a barrierless pathway for sulfonium ion 27 to react with the cycloalkene.
- Brydon, Samuel C.,Lim, Shea Fern,Khairallah, George N.,Ma?tre, Philippe,Loire, Estelle,Da Silva, Gabriel,O'Hair, Richard A. J.,White, Jonathan M.
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- Three-component difunctionalization of alkenes leading to β-acetamido sulfides and β-acetoxy sulfides
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A novel method for the synthesis of β-acetamido sulfides via NBS-mediated aminosulfenylation of alkenes with thiophenols and nitriles under metal-free conditions has been described. And β-acetamido sulfides were also synthesized with 1-(arylthio)pyrrolidine-2,5-diones as substrates and HBr as an additive. On the other hand, iodine-catalyzed 1,2-acetoxysulfenylation of alkenes by using (diacetoxyiodo)benzene as an oxygen source to synthesise various β-acetoxy sulfides was described as well.
- Wang, Dingyi,Yan, Zhaohua,Xie, Qihuang,Zhang, Rongxing,Lin, Sen,Wang, Yuanxing
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p. 1998 - 2002
(2017/03/11)
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- Catalytic chalcogenylation under greener conditions: A solvent-free sulfur- and seleno-functionalization of olefins via I2/DMSO oxidant system
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Herein, we report a solvent- and metal-free methodology for the alkoxy-chalcogenylation of styrenes, using molecular iodine as a catalyst, DMSO as a stoichiometric oxidant, and different nucleophiles under microwave irradiation. This eco-friendly approach afforded the desired products in good to excellent yields in only 10 min. In addition, using the same protocol, we carried out the cyclization reaction of relevant molecules, such as lapachol derivatives.
- Vieira, André A.,Azeredo, Juliano B.,Godoi, Marcelo,Santi, Claudio,Da Silva Júnior, Eufranio N.,Braga, Antonio L.
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p. 2120 - 2127
(2015/05/12)
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- PhI(OAc)2/KI mediated 1,2-acetoxysulfenylation of alkenes: Facile synthesis of β-acetoxysulfides
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A convenient method for 1,2-acetoxysulfenylation of alkenes using disulfide promoted by (diacetoxyiodo)benzene (PhI(OAc)2, DIB)/KI was developed. The reaction is highly regioselective for styrene derivatives while aliphatic alkenes lead to a mixture of two regioisomers.
- Muangkaew, Charoensak,Katrun, Praewpan,Kanchanarugee, Patcharaphon,Pohmakotr, Manat,Reutrakul, Vichai,Soorukram, Darunee,Jaipetch, Thaworn,Kuhakarn, Chutima
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p. 8847 - 8856
(2013/09/23)
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- Copper-catalyzed 1,2-hydroxysulfenylation of alkene using disulfide via cleavage of the S-S bond
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(Chemical Equation Presented) Copper-catalyzed 1,2-hydroxysulfenylation of alkenes can be carried out by the use of disulfides and acetic acid in air. This reaction regio- and anti-selectively gave the corresponding 1,2-acetoxysulfides. Furthermore, the p
- Taniguchi, Nobukazu
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p. 7874 - 7876
(2007/10/03)
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- Novel ipso-Substitution of p-Sulfinylphenols through the Pummerer-Type Reaction: A Selective and Efficient Synthesis of p-Quinones and Protected p-Dihydroquinones
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The treatment of p-sulfmylphenols 3a-q with trifluoroacetic anhydride caused a Pummerer-type reaction on aromatic rings and concomitant desulfurization to give mixtures of the corresponding p-dihydroquinones 9 and p-quinones 10, which were subsequently oxidized under mild conditions to provide high yields of p-quinones 10. On the other hand, the treatment of p-(phenylsulfinyl)-phenyl ethers 6 with trifluoroacetic anhydride in the presence of styrene caused the direct ipso-substitution of the sulfinyl groups into trifluoroacetoxy groups, giving the protected dihydroquinones 14 in high yields. Both types of reactions were generally completed below room temperature within 1 h and compatible with various functional groups such as the allyl, carbonyl, ester, amide, and silyloxy groups. The preparation of the p-sulfmylphenols 3 and the silyl ethers 6 is also described through p-specific thiocyanation of phenols followed by the Grignard reaction and oxidation.
- Akai, Shuji,Takeda, Yoshifumi,Iio, Kiyosei,Takahashi, Kenji,Fukuda, Nobuhisa,Kita, Yasuyuki
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p. 5526 - 5536
(2007/10/03)
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