- High-Yield Lithiation of Azobenzenes by Tin-Lithium Exchange
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The lithiation of halogenated azobenzenes by halogen-lithium exchange commonly leads to substantial degradation of the azo group to give hydrazine derivatives besides the desired aryl lithium species. Yields of quenching reactions with electrophiles are therefore low. This work shows that a transmetalation reaction of easily accessible stannylated azobenzenes with methyllithium leads to a near-quantitative lithiation of azobenzenes in para, meta, and ortho positions. To investigate the scope of the reaction, various lithiated azobenzenes were quenched with a variety of electrophiles. Furthermore, mechanistic 119Sn NMR spectroscopic studies on the formation of lithiated azobenzenes are presented. A tin ate complex of the azobenzene was detected and characterized at low temperature.
- Strueben, Jan,Lipfert, Matthias,Springer, Jan-Ole,Gould, Colin A.,Gates, Paul J.,S?nnichsen, Frank D.,Staubitz, Anne
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p. 11165 - 11173
(2015/11/10)
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- Mechanism of the Reaction of Sodium Hydroxide and Nitrobenzylsulphones
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Aqueous sodium hydroxide reacts with sulphonyl>acetic acid (1) to give 4,4'-diformylazoxybenzene and 4,4'-dicarboxyazoxybenzene as the main products, while in 50percent water-dioxane medium the products are 4,4'-dihydroxymethylazoxybenzene, 4,4'-dicarboxyazoxybenzene besides 4-carboxy, 4'-hydroxymethylazoxybenzene and its isomer. 4-Nitrosobenzaldehyde is an intermediate in this reaction which via a Cannizzaro reaction gives the reaction products.Other 2-, 3- and 4-nitrobenzyl sulphones are studied.
- Riad, Y.,Asaad, A. Naguib,Nahas, Hind Moustafa El,Madkour, A. Emad El Din
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p. 157 - 172
(2007/10/03)
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