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Synlett 2002(6): 0915-0918
DOI: 10.1055/s-2002-31918
LETTER
© Georg Thieme Verlag Stuttgart · New York

The Base-Induced Fragmentation of N,N-Dibenzyl-N′-aryltriazenes

Matthias E. P. Lormanna, Stefan Dahmenb, Frank Avemariaa, Frank Lauterwassera, Stefan Bräse*a
a Kekulé-Institut für Organische Chemie und Biochemie der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany
Fax: +49(228)739608; e-Mail: braese@uni-bonn.de;
b Institut für Organische Chemie der RWTH Aachen, Professor-Pirlet-Strasse 1, 52074 Aachen, Germany
Further Information

Publication History

Received 21 December 2001
Publication Date:
07 February 2007 (online)

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Abstract

Deprotonation of N,N-dibenzyl-N"-aryltriazenes, either in liquid phase or on solid support, by a strong base (n-BuLi or LDA) leads to fragmentation of the N-N single bond to give an imine and a diazenyl anion, which decomposes by loss of nitrogen to the parent aryl anion. The imine is deprotonated to give a 2-aza allyl anion, which is subsequently trapped by electrophiles. As an overall result, this fragmentation of the T1 triazene anchoring group represents a new traceless cleavage mode of this linker. The same mode of fragmentation was observed for the T2 linker leading to 2-aza allyl anions in liquid phase. The dibenzylamino moiety is apparently crucial since pyrrolidinodiazenylarenes can be metallated at the heterocycle without cleavage.

Key words

triazenes - diazenyl anions - azaallyl anions - umpolung - solid phase synthesis

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This reaction is similar to the aza-1,2-Wittig rearrangement reaction with concurrent loss of nitrogen.

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All new non-polymeric compounds were characterized by means of NMR, MS, IR, and elemental analysis.