Convenient Access to Bicyclic and Tricyclic Diazenes

Heating the tosylhydrazone of an ω-alkenyl ketone or aldehyde to reflux in toluene in the presence of K2CO3 delivered the bicyclic diazene. Irradiation of the diazene converted it to the cyclopropane. This appears to be a generally useful method for the construction of substituted cyclopentanes and cyclohexanes.