Reaction of the 5-Azoniafulvene Ion with Enamines: A New Approach to Pyrrolizines |
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Authors: | Daniel Schrer Vladimir Jindra Alain O Bringhen Ulrich Burger |
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Institution: | Daniel Schärer,Vladimir Jindra,Alain O. Bringhen,Ulrich Burger |
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Abstract: | The synthesis of N,N-dimethyl-N-(pyrro-1-yl)methyl]anilinium chloride ( 14 ) and of the corresponding p-toluidinium salt 15 is described. These salts, when dissolved in polar solvents, are shown to be in equilibrium with 1-(chloromethyl)pyrrole ( 17 ) and thereby potentially with the 5-azoniafulvene ion ( 2 ). Consequently, they react under very mild conditions (MeCN, 60°) with enamines to give pyrrolizine derivatives in acceptable yield (40–50°). The process is rationalized in terms of an initial Mannich-type reaction which is immediately followed by acyclization. |
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