1‐Aryl‐3,3‐diisopropyltriazenes: An Easily Accessible and Particularly Stable Class of Triazenes Towards Strong Basic and Lewis Acid Conditions

The stability of various substituted aryl-3,3-dialkyltriazenes, valuable synthetic intermediates, under several reaction conditions has been evaluated. To do so, anthranilonitrile and 2-amino-6-(trifluoromethyl)benzonitrile have been reacted in the presence of different secondary amines to the corresponding 1-(2-R-phenyl)-3,3-dialkyltriazenes. These compounds have been submitted to a series of different reaction conditions with special emphasis on strong basic and metal/acid reductive conditions in order to test the stability of the triazene moiety under these circumstances. Generally, triazenes are unstable in metal/acid reducing conditions. A lot of 1-aryl-3,3-dialkyltriazenes are known to undergo deprotonation in α-position of N-3 in the presence of strong bases, thus limiting the scope of action of this class of compounds. Among the tested substances, most triazenes were stable in the presence of titanium isopropoxide and/or strong nucleophiles. 1-(2-R-phenyl)-3,3-diisopropyltriazenes turned out to be particularly stable under strong basic conditions. 1,2-addition reactions in the presence of Grignard reagents or lithiated compounds, showed in most cases no side products resulting from a degradation of the triazene function. The same was true for the titanium-catalyzed Kulinkovich–de Meijere cyclopropanation or for reductive amination. In both cases, no triazene degradation products could be detected. 1-(2-R-phenyl)-3,3-diisopropyltriazenes were even stable in the presence of strong Lewis acids like trimethylaluminium. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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