- Palladium-Catalyzed Coupling of Sulfonylhydrazones with Heteroaromatic 2-Amino-Halides (Barluenga Reaction): Exploring the Electronics of the Sulfonylhydrazone
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This paper describes a new reactivity of the Pd-catalyzed coupling of 2-amino-3-bromo-aromatic and heteroaromatic compounds with sulfonylhydrazones (Barluenga reaction).The new catalyst system and modulation of the electronic nature of hydrazone that were needed for successful reaction are described herein.
- Tan, Hongyu,Houpis, Ioannis,Liu, Renmao,Wang, Youchu,Chen, Zhilong,Fleming, Matthew J.
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supporting information
p. 1044 - 1048
(2015/09/01)
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- Transition-metal-free direct arylation of anilines
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Aryne arylation: A new method of direct arylation is reported for aniline substrates. The reaction uses benzyne to synthesize a variety of aminobiaryls under mild conditions (see scheme), requiring no stoichiometric metalation or transition-metal catalysis. An ene mechanism is implicated, and conveys excellent functional group tolerance relative to metal-mediated processes. Copyright
- Pirali, Tracey,Zhang, Fengzhi,Miller, Anna H.,Head, Jenna L.,McAusland, Donald,Greaney, Michael F.
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p. 1006 - 1009
(2012/02/16)
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- Radical dearomatization of arenes and heteroarenes
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The stannane-mediated benzeneselenol-catalyzed addition of aryl iodides to a range of arenes and aromatic hetereocycles has been studied. With furan, thiophene, and several carbocyclic arenes, the addition takes place with quenching of the adduct radical by the catalytic selenol leading to moderate yields of aryl-dihydroarenes. With nitrogen heterocycles, on the other hand, it was not possible to suppress aromatization of the adduct radical and fully aromatized products were isolated. Aryl iodides bearing hydrogen bond donating groups in the ortho-position add to nitrogen heterocycles with high selectivity ortho- to the nitrogen, affording a simple one-step synthesis of potential chelating ligands. While 2-iodophenol is an excellent aryl radical source in these reactions, the homologous 1-iodo-2-naphthol fails owing to its reaction with diphenyl diselenide, which gives 1-phenylseleno-2-naphthol in high yield.
- Crich, David,Patel, Mitesh
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p. 7824 - 7837
(2007/10/03)
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- N- and C-attacks on aromatics of phenylnitrenium ion generated from N-phenylhydroxylamine in the presence of trifluoroacetic acid containing polyphosphoric acid or trifluoroacetic anhydride
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A phenylnitrenium ion formed from N-phenylhydroxylamine in the presence of trifluoroacetic acid (TFA) containing polyphosphoric acid (PPA) interacts with the counterion -O2CCF3 and the unshared electron-pair of H2O, showing Hammett's ρ values -5.2 and -4.0 for N- and C-attacks on aromatics PhX (X = H, Me, Et, Ph and Cl), respectively. The ratio N-/C-attack for this nitrenium ion is lower than for the nitrenium ion interacting with only the counterion; the latter nitrenium ion is generated by the use of trifluoroacetic anhydride (TFAA) instead of PPA or by reaction of phenyl azide with aromatics in TFA. The ratio for the former nitrenium ion is affected by the aromatic substituent X:X = Me > X = Et > X = Ph > X = H > X = OMe at 20 and 50°C. The order for X = Cl is between those of X = H and X = Ph at 20°C, but highest at 50°C. The ratio is increased by higher reaction temperature and by decreased concentration of TFA. The results are demonstrated from the mechanistic viewpoint for the nitrenium ions.
- Takeuchi, Hiroshi,Taniguchi, Tomohito,Ueda, Takahiro
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p. 295 - 300
(2007/10/03)
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