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Communication | Regular issue | Vol 22, No. 1, 1984, pp.21-26
Published online, 1st January, 1970
DOI: 10.3987/R-1984-01-0021
The Chemistry of an Isolable Azomethine Ylide

Rolf Huisgen* and Karl Niklas

*Institut für Organische Chemie, Universität München, Karlstrasse 23, D-80333 München, Germany


The 4-isoxazoline 3 undergoes ring contraction to the acylaziridine 5 which is converted to the azomethine ylide 4. The small influence of solvent polarity on the rate constant of the conversion 34 suggests a mechanism via a trimethylene type species for the rate-determining step. Whereas 4 is the first azomethine ylide which can be isolated without being stabilized by aromatic resonance, the ylides 20 - 22 dimerize to piperazine derivatives. 1,3-Dipolar cycloadditions of the azomethine ylides 4 and 20 - 22 are described.