High‐Yield Lithiation of Azobenzenes by Tin–Lithium Exchange |
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| Authors: | Jan Strueben Matthias Lipfert Jan‐Ole Springer Colin A. Gould Dr. Paul J. Gates Prof. Dr. Frank D. Sönnichsen Prof. Dr. Anne Staubitz |
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| Affiliation: | 1. Otto‐Diels‐Institute for Organic Chemistry, University of Kiel, Otto‐Hahn‐Platz 3‐4, 24098 Kiel (Germany);2. School of Chemistry, University of Bristol, Cantock's Close, Bristol BS7?1TS (UK) |
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| Abstract: | 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. |
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| Keywords: | azo compounds lithiation metalation synthetic methods tin |
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