Synthesis and chemistry of new spiro‐Δ 1 ‐pyrazoline

In explorations of syntheses and chemistry of spiroheterocycles, we found that the reaction of 2‐diazopropane with ( E )‐α‐arylidenepyrrolin‐2‐one, ( E )‐α‐arylidene‐γ‐butyrolactone, and ( E )‐arylidene‐ N ‐arylsuccinimide derivatives produced spiro‐Δ 1 ‐pyrazolines. The photolysis of Δ 1 ‐pyrazolines has led to cyclopropanes. The structures of the obtained adducts have been assigned by means of spectroscopic measurements. J. Heterocyclic Chem., (2011).