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High‐Yield Lithiation of Azobenzenes by Tin–Lithium Exchange
Author(s) -
Strueben Jan,
Lipfert Matthias,
Springer JanOle,
Gould Colin A.,
Gates Paul J.,
Sönnichsen Frank D.,
Staubitz Anne
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201500003
Subject(s) - transmetalation , electrophile , tin , lithium (medication) , azobenzene , chemistry , methyllithium , yield (engineering) , photochemistry , aryl , halogen , quenching (fluorescence) , polymer chemistry , organic chemistry , materials science , molecule , metallurgy , fluorescence , endocrinology , medicine , alkyl , physics , quantum mechanics , catalysis
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 119 Sn 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.