The [3+2] cycloaddition of diphenyldiazomethane and ethyl diazoacetate with itaconic anhydride. A new access to spiranic cyclopropane derivatives

The reaction of itaconic anhydride with N2:CHCO2Et or Ph2C:N2 gave the expected spiro-derivs., which spontaneously rearranged; specifically, the adduct from Ph2C:N2 loses a dinitrogen mol., yielding a spirocyclopropane related to the known 5-azaspiro[2.4]heptane-4,6-diones or 5-azaspiro[2.4]heptanes.