The first example of the generation and trapping of diazospiropentane by unsaturated compounds

Alkaline hydrolysis of N-spiropentyl-N-nitrosourea at –50 °C generates unknown diazospiropentane in situ, which is trapped with methyl methacrylate or 3,3-dimethylcyclopropene yielding the corresponding 1-pyrazolines with a spiropentane fragment in the molecule. Some chemical transformations of the products obtained are performed.