- Cleavage of 5-Nitro-2-(trimethylsilylmethyl)thiophene by Methanolic Sodium Methoxide. U.V. Spectroscopic and Solvent Isotope Effect Evidence for Generation of the Anion (1-)
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The reaction of 5-nitro-2-(trimethylsilylmethyl)thiophene with NaOMe-MeOH involves generation of the observable anion (1-) with a solvent isotope effect k(MeOH)/k(MeOD) of 0.5, followed by protonation of the anion with a solvent isotope effect of 10; the results confirm that cleavages of RSiMe3 compounds by NaOMe-MeOH involve separation of the anions R(1-), and that the isotope effect in the reaction of R(1-) with MeOH depends greatly on the degree of conjugative delocalization of the negative charge, not just on the acidity of RH.
- Dembech, Pasquale,Eaborn, Colin,Seconi, Giancarlo
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- One-Pot Deoxygenation and Substitution of Alcohols Mediated by Sulfuryl Fluoride
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Sulfuryl fluoride is a valuable reagent for the one-pot activation and derivatization of aliphatic alcohols, but the highly reactive alkyl fluorosulfate intermediates limit both the types of reactions that can be accessed as well as the scope. Herein, we report the SO2F2-mediated alcohol substitution and deoxygenation method that relies on the conversion of fluorosulfates to alkyl halide intermediates. This strategy allows the expansion of SO2F2-mediated one-pot processes to include radical reactions, where the alkyl halides can also be exploited in the one-pot deoxygenation of primary alcohols under mild conditions (52-95% yield). This strategy can also enhance the scope of substitutions to nucleophiles that are previously incompatible with one-pot SO2F2-mediated alcohol activation and enables substitution of primary and secondary alcohols in 54-95% yield. Chiral secondary alcohols undergo a highly stereospecific (90-98% ee) double nucleophilic displacement with an overall retention of configuration.
- Epifanov, Maxim,Mo, Jia Yi,Dubois, Rudy,Yu, Hao,Sammis, Glenn M.
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p. 3768 - 3777
(2021/03/01)
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- Synthesis of dinitro-substituted furans, thiophenes, and azoles
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Direct nitration of the corresponding mononitro furans with fuming nitric acid, thiophenes with acetyl nitrate, and thiazoles with trifluoroacetyl nitrate, gave dinitro-substituted furans, thiophenes, and thiazoles. The nitrations of 2-alkylthiophenes wit
- Katritzky, Alan R.,Vakulenko, Anatoliy V.,Sivapackiam, Jothilingam,Draghici, Bogdan,Damavarapu, Reddy
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p. 699 - 706
(2008/09/21)
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- The synthesis of highly active thiophene ring-containing chromophore components for photonic polymers based on a newly designed route
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2-Aminothiophene derivatives are the key intermediates for the present synthesis. It is known that the synthesis of 2-aminothiophene is troublesome although it is a rather simple heterocycle. In this work, an early report was newly developed as a basis for the efficient synthesis of thiophene-ring-containing chromophore components for photonic polymers. 2-Amino-5-nitrothiophene and 2-amino-3,5-dinitrothiophene were synthesized in excellent yield. After diazotization, the 2-aminothiophene derivatives were directly treated with N-phenyldiethanolamine to afford two-electron push-pull compounds. A similar styryl compound was also prepared. All of these chromophore molecules have further polymerizable hydroxy groups on one end of the molecule. These compounds are currently showing interesting potential in making highly sensitive, nonlinear optical polymeric materials. The Royal Society of Chemistry 1999.
- Yuquan, Shen,Yuxia, Zhao,Zao, Li,Jianghong, Wang,Ling, Qiu,Shixiong, Liu,Jianfeng, Zhai,Jiayun, Zhou
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p. 3691 - 3695
(2007/10/03)
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- ALKYLATION ORIENTATION RULES IN CONJUGATE ADDITION OF GRIGNARD REAGENTS TO NITROPYRROLE AND NITROTHIOPHENE SYSTEMS
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Conjugate addition of various Grignard reagents to 1-alkyl-2-nitropyrroles and to 2-nitrothiophene has been investigated. 1-Alkyl-2-nitropyrroles undergo alkylation at 3 and 5 positions with prevalence of the latter isomer.On the contrary, in the 2-nitrothiophene system, formation of the 3-isomer prevails.In both systems, a bulkier Grignard reagent favours the 5-isomer formation.This trend can be reversed increasing steric hindrance exerted by the 1-substituent of 2-nitropyrrole. 1-(Tri-isopropylsilyl)-3-nitropyrrole and 3-nitrothiophene give exclusively the 2-isomer.This reaction allows 2-alkyl-3-nitrothiophenes and pyrroles to be synthesized with a one-pot procedure instead of the classical multi stage reaction.
- Ballini, Roberto,Bartoli, Giuseppe,Bosco, Marcella,Dalpozzo, Renato,Marcantoni, Enrico
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p. 6435 - 6440
(2007/10/02)
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