The reaction of 1,5-diazabicyclo[3.1.0]hexane and its 6-methyl and 6-phenyl
derivatives with primary and secondary alkyl halides results in opening of
the diaziridine ring and elimination of the N-methylene group with formati
on of 1-alkyl-4,5-dihydropyrazoles. The alkyl group in the product is the s
ame as in the initial alkyl halide.