Formation of the 5-Azoniafulvene Ion and its Benzo-annellated Analogue from N-Mannich Bases of Pyrrole and Indole |
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Authors: | Ulrich Burger Alain O Bringhen Philippe J Wirthner Jean-Claude Schrer |
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Institution: | Ulrich Burger,Alain O. Bringhen,Philippe J. Wirthner,Jean-Claude Schärer |
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Abstract: | 1-Dialkylaminomethylpyrroles are shown to behave in many respects like aminals. Acylation by an acid chloride, for instance, occurs normally at the amine-type N-atom rather than at the pyrrole ring. Spontaneous cleavage of the resulting quaternary acylammonium salts affords the 5-azoniafulvene ion ( 3 ). This higly reactive iminium ion, and its benzo-annellated analogue ( 4 ) can be trapped by electron rich aromatic compounds such as N-methylpyrrole or N,N-dimethylaniline. More elaborate N-Mannich bases are accessible by addition of indoles to enamines. |
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