title: High-yield lithiation of azobenzenes by tin-lithium exchange.
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 (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.
authors.affiliation: Otto-Diels-Institute for Organic Chemistry, University of Kiel, Otto-Hahn-Platz 3-4, 24098 Kiel (Germany).
authors.forename: Jan
authors.initials: J
authors.lastname: Strueben
authors.affiliation: Otto-Diels-Institute for Organic Chemistry, University of Kiel, Otto-Hahn-Platz 3-4, 24098 Kiel (Germany).
authors.forename: Matthias
authors.initials: M
authors.lastname: Lipfert
authors.affiliation: Otto-Diels-Institute for Organic Chemistry, University of Kiel, Otto-Hahn-Platz 3-4, 24098 Kiel (Germany).
authors.forename: Jan-Ole
authors.initials: JO
authors.lastname: Springer
authors.affiliation: Otto-Diels-Institute for Organic Chemistry, University of Kiel, Otto-Hahn-Platz 3-4, 24098 Kiel (Germany).
authors.forename: Colin A
authors.initials: CA
authors.lastname: Gould
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS7 1TS (UK).
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Gates
authors.affiliation: Otto-Diels-Institute for Organic Chemistry, University of Kiel, Otto-Hahn-Platz 3-4, 24098 Kiel (Germany).
authors.forename: Frank D
authors.initials: FD
authors.lastname: Sönnichsen
authors.affiliation: Otto-Diels-Institute for Organic Chemistry, University of Kiel, Otto-Hahn-Platz 3-4, 24098 Kiel (Germany). astaubitz@oc.uni-kiel.de.
authors.forename: Anne
authors.initials: A
authors.lastname: Staubitz
keywords: azo compounds; lithiation; metalation; synthetic methods; tin