Different reactivities of regioisomeric azimines, adducts of phthalimidonitrene with 5-bromospiro[1-pyrazoline-3,1 '-cyclopropane]

The addition of the phthalimidonitrene fragment. resulting from oxidation o f N-aminophthalimide by lead tetraacetate at -20 to -30 degreesC, to the N= N-bond of 5-bromospiro[1-pyrazoline-3,1'-cyclopropane] (1) affords, apart f rom the stable 5-bromoN-(spiro[1-pyrazolinio-3,1-cyclopropane])-N-phthalimi doamide (azimine 2), regioisomeric azimine 3, which is completely transform ed into 3-acetoxy-N-(spiro[1-pyrazolinio-5,1'-cyclopropane])- N-phthalimido amide (4) under the reaction conditions. The acetoxy group in this product easily. undergoes nucleophilic substitution on treatment with MeOH. NaN3. o r the starting bromopyrazoline 1. The structures of azimines obtained were established using N M R spectra. and the structure of the product of reacti on of 4 with 1 was additionally proved by X-ray difraction data.