Preparation and Properties of a Structually Novel Heterocyclic Dispiro Compound, 3,10-Dimethyl-3,10-diazadispiro[5.0.5.4]hexadeca-1,4,8,11-tetraene

The two-electron reduction of 3 with sodium amalgam in degassed acetonitrile affords 4 in quantitative yield. Under deoxygenerated conditions, 4 is stable for a long time at room temperature, but slowly undergoes an opening of the cyclohexane ring skeleton with elimination of methyl groups to yield 5 at about 200 °C. At the same time, a small amount of 6 is obtained by fission of a CC single bond of the cyclohexane ring skeleton with the transfer of hydrogen atom.