INTRAMOLECULAR THERMAL TRANSFORMATIONS OF <i>N</i>-PHTHALIMIDOAZIRIDINES: 1,3-DIPOLAR CYCLOADDITION AND REARRANGEMENTS

Abstract

The intramolecular thermal cycloaddition of N-phthalimidoaziridines at multiple bonds of substituents with the intermediate formation of azomethine ylides leads to condensed pyrrole derivatives, in which the five-membered ring is adjacent to a five-, six-, or seven-membered ring. Rearrangements, which sometimes become the predominant reactions, compete with cycloaddition. Thus, aziridines with aryl substituents readily isomerize to give imines with a 1,2-shift of the phthalimide group to one of the carbon atoms. Aziridines with one electron-withdrawing substituent probably do not open to give 1,3-dipoles but rather undergo a Cope-type rearrangement involving the three-membered ring and C=O bond of the second substituent. Even in intramolecular reactions, very low activity is found for the cyano group triple bond and aromatic ring bonds as dipolarophiles.

Authors: M. A. Kuznetsov, A. S. Pan'kova, V. V. Voronin, and N. A. Vlasenko.

English translation in Chemistry of Heterocyclic Compounds, 2011, 47 (11), pp 1353-1366

http://link.springer.com/article/10.1007/s10593-012-0921-6