perhydrocyclopentaaphenanthrene

Perhydrocyclopentaaphenanthrene, also written as perhydrocyclopenta[a]phenanthrene, is a fully saturated polycyclic hydrocarbon. It represents the hydrogenated form of the cyclopenta[a]phenanthrene skeleton, consisting of a cyclopentane ring fused to three six-membered rings in a phenanthrene-type core. In this saturated state, all carbon–carbon bonds are single bonds, with no aromatic or alkenic character.

Structurally, the molecule features four fused rings: one cyclopentane and three cyclohexane rings arranged in a rigid tetracyclic framework. This arrangement is the saturated core that underpins the perhydro cyclopenta[a]phenanthrene system, a skeleton widely referenced in steroid chemistry. The perhydro form is often discussed as a simple, non-aromatic model of the steroid nucleus, useful for conformational and stereochemical studies in the absence of double bonds.

Synthesis of perhydrocyclopenta[a]phenanthrene-type structures typically involves the complete hydrogenation of the corresponding polycyclic aromatic system, such as cyclopenta[a]phenanthrene or related PAHs. As a fully saturated hydrocarbon, it is nonpolar and largely insoluble in water, with solubility in many organic solvents. Its physical properties are characteristic of high-boiling, nonpolar hydrocarbons and are influenced by the specific substituents present on the fused-ring system.

See also: cyclopenta[a]phenanthrene; perhydro steroids; steroid nucleus; polycyclic hydrocarbons.