(4.4.4)Propellahexaene by Triple Shapiro Degradation. Structural and Electronic Properties of This Maximally Unsaturated Hydrocarbon and Consequences of O-Methylation of Its (4.4.4)Propellatrienetrione Precursors.

The structural and spectroscopic features of 5 are critically defined, the thermal stabilities of the hexaene and two trimethoxy derivatives are compared, and the Diels-Alder reactivities of 5 and related molecules are surveyed. (5: [4.4.4] Propellahexaene)