- "transition-metal-free" synthesis of carbazoles by photostimulated reactions of 2′-halo[1,1′-biphenyl]-2-amines
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An efficient and simple protocol for the preparation of a series of 9H-carbazoles by photostimulated SRN1 substitution reactions is presented. Substituted 9H-carbazoles were synthesized in low to excellent yields (up to 96%) through an intramolecular C-N bond formation of 2′-halo[1,1′-biphenyl]-2-amines by the photoinitiated SRN1 mechanism under mild and "transition-metal-free" conditions. The biphenylamines used as substrates were obtained with isolated yields ranging from 21% to 84% by two approaches: (A) the cross-coupling Suzuki-Miyaura reaction and (B) the radical arylation of anilines. Some key aspects of the proposed mechanism were evaluated at the B3LYP/6-311+G? level.
- Guerra, Walter D.,Rossi, Roberto A.,Pierini, Adriana B.,Barolo, Silvia M.
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p. 928 - 941
(2015/01/30)
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- Selective Aromatic N-Substitution with N-(4-Tolyl)hydroxylamine by Addition of Polar Aprotic or Diethereal Solvent
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Amination of anisole and toluene with N-(4-tolyl)hydroxylamine in trifluoroacetic acid was tuned to regioselectively provide the corresponding diarylamine by partial replacement of trifluoroacetic acid with a polar aprotic or a diethereal solvent. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Takeuchi, Hiroshi,Tateiwa, Jun-Ichi,Hata, Suguru,Tsutsumi, Keisuke,Osaki, Yoshinori
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p. 3920 - 3922
(2007/10/03)
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- Reaction of n-aminophthalimide derivatives with aluminum chloride in benzene
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The reaction of N-aminophthalimide derivatives with AlCl3 in benzene has been investigated. From N-amino- and N-benzamidophthalimide (1a and 1b), N-amino- and N-benzamido3,3-diaryl-2,3-dihydroisoindol-1-ones (2) are obtained in high yield by initial attack of benzene on the imide carbonyl, assisted by the neighboring nitrogen atom. From N-arylaminophthalimide derivatives (4), the N-N bond is cleaved heterolytically to give an arylnitrenium ion and canonical forms involving the arene which are trapped by benzene to give aminobiaryls and N-arylanilines.
- Ohwada, Atsushi,Li, Hao,Sakamoto, Takeshi,Kikugawa, Yasuo
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p. 225 - 233
(2007/10/03)
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- INTER- AND INTRA-MOLECULAR AROMATIC N-SUBSTITUTION BY ARYLNITRENIUM-ALUMINIUM CHLORIDE COMPLEXES GENERATED FROM ARYL AZIDES IN THE PRESENCE OF ALUMINIUM CHLORIDE
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Reactions of phenyl azide with aromatic compounds ( i. e. benzene, toluene, ethylbenzene, cumene, anisole, and bromobenzene ) in the presence of AlCl3 gave diarylamines, whwreas those of phenyl azides with an electron-donating group such as Me and OMe yield little of the corresponding diarylamines ( tarformation takes place ).The reaction of 4-nitrophenyl azide with benzene in the presence of AlCl3 gave 4-nitrophenyl(phenyl)amine and a C-substitution product, 2-amino-5-nitrobiphenyl.Decomposition of 2-azidophenyl(phenyl)methane and 2-azidobiphenyls in CH2Cl2 in the presence of AlCl3 underwent an N-cyclization to afford 9,10-dihydroacridine and carbazoles, respectively, in good yields.The kinetic data on the decomposition of aryl azides and a Hammet plot ( with p= -6.0 ) for the formation of diarylamines suggest that the products are formed by an aromatic N-substitution of arylnitrenium-AlCl3 complexes via azide-AlCl3 complexes.We further argue the character of arylnitrenium-AlCl3 complexes.
- Takeuchi, Hiroshi,Maeda,Munenori,Mitani, Michiharu,Koyama, Kikuhiko
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- N- and C-Attacks of Phenylnitrenium Ions Generated from Phenyl Azides in the Presence of Trifluoroacetic Acid and/or Trifluoromethanesulphonic Acid
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Phenylnitrenium ions were generated from phenyl azides in the presence of trifluoroacetic acid (TFA) and/or trifluoromethanesulphonic acid (TFSA).Unsubstituted phenylnitrenium ions and those with an electron-withdrawing group such as NO2 or CN undergo aromatic N-substitution, whereas those with an electron-donating group such as Me, OMe, CH2Ph, or Ph undergo C-substitution, hydrogen abstraction, and tar formation.The special character of TFA and TFSA as compared with other acids is discussed.
- Takeuchi, Hiroshi,Takano, Katsuyuki
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p. 611 - 618
(2007/10/02)
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- A TRIFLUOROMETHANESULFONIC ACID-CATALYZED REACTION OF ARYLHYDRAZINES WITH BENZENE
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Arylhydrazines reacted with benzene in the presence of trifluoromethanesulfonic acid (TFSA) to give aminobiphenyls.This is a general method for the synthesis of aminobiphenyls.
- Ohta, Toshiharu,Miyake, Shinji,Shudo, Koichi
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p. 5811 - 5814
(2007/10/02)
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- Acid-Catalyzed Reactions of N-Arylhydroxylamines and Related Compounds with Benzene. Iminium-Benzenium Ions
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N-Arylhydroxylamines react with benzene in the presence of trifluoroacetic acid (TFA) at room temperature to give diphenylamines.When TFA was replaced by a strong acid, trifluoromethanesulfonic acid (TFSA), the major products were aminobiphenyls.The nature of the reaction was explored by reactions of 4-substituted phenylhydroxylamines and dialkylaniline N-oxides with benzene.Thus, it was demonstrated that the reactive intermediates are onium-benzenium dications which are trapped by benzene to give aminobiphenyls by a mechanism similar to the Friedel-Krafts alkylation.Further evidence for the proposed reaction mechanism was the observation that nitrosobenzene and azoxybenzene reacted with benzene to give analogous products in the presence of the stronger acid.
- Shudo, Koichi,Ohta, Toshiharu,Okamoto, Toshihiko
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p. 645 - 653
(2007/10/02)
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