Formation and thermal decomposition of adducts of phthalimidonitrene with spiro(1-pyrazolinecyclopropanes)

Oxidation of N-aminophthalimide with lead tetraacetate in the presence of s piro(1-pyrazolinecyclopropanes) at temperature from -20 degrees C to -30 de grees C resulted in the formal generation of phthalimidonitrene followed by its addition at the N=N bond of the pyrazoline ring to form 5(3)-substitut ed N-{spiro[1-pyrazolinio-3(5),1'-cyclopropane]}-N-phthalimidoamides (azimi nes), whose regioisomeric compositions were determined to a large extent by the nature of the substituents in the pyrazoline ring. The structures of p hthalimidoazimines were established based on the NMR spectra and X-ray diff raction data. Thermal conversions of the resulting adducts, which proceeded either with retention or with opening of the spiro-fused cyclopropane ring , were studied.