Interconversions of 1,3-dipolar cycloaddition products of azomethine ylides and ylidenemalononitriles

New substituted spiropyrrole(zi)dynes were synthesized by the 1,3-dipolar cycloaddition reaction of ylidenemalononitriles and azomethine ylides generated in situ by condensation of isatin and α-amino acids (sarcosine, proline). The products′s features of the regio- and diastereochemical structure were elucidated depending on the nature of the amino acid and the reaction conditions. Based on data from the analysis of the spectra of cycloaddition products obtained under various conditions, as well as some additional experiments, a probable scheme for the formation of products was proposed, including retro-1,3-dipolar cycloaddition and the retro-Mannich reaction. Methods for the selective synthesis of isomeric spiropyrrolizidines were developed.