Scope and Applications of 1,3-Dipolar Cycloadditions

An interesting variation of the 1,3-DPCA involves generation of 1,3-dipoles from three-membered rings. As an example, aziridines 3 and 4 give adducts derived from apparent formation of 1,3-dipoles 5 and 6, respectively.  

Martin-Vila, N. Hanafi, J. M. Jimenez, A. Alvarez-Larena, J. F. Piniella, V. Branchadell, A. Oliva, 

Ring opening is most facile for aziridines that have an EWG to stabilize the carbanion center in the dipole. The evidence for the involvement of 1,3-dipoles as discrete intermediates includes the observation that the reaction rates are independent of dipolarophile concentration. This fact indicates that the ring opening is the 

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