Gonane (cyclopentanoperhydrophenanthrene) is a chemical compound with formula , whose structure consists of four

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

rings fused together: three

cyclohexane Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexan ...

units and one

cyclopentane Cyclopentane (also called C pentane) is a highly flammable alicyclic compound, alicyclic hydrocarbon with chemical formula C5H10, C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and ...

. It can also be viewed as the result of fusing a cyclopentane molecule with a fully

hydrogenated Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organi ...

molecule of

phenanthrene Phenanthrene is a polycyclic aromatic hydrocarbon (PAH) with formula C14H10, consisting of three fused benzene rings. It is a colorless, crystal-like solid, but can also appear yellow. Phenanthrene is used to make dyes, plastics, pesticides, expl ...

, hence the more descriptive name "perhydrocyclopenta henanthrene". The non-systematic version of the above name is "cyclopentanoperhydrophenanthrene". It has no double bonds, that is, it is completely saturated and is considered the main structure of

steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...

s, often referred to as the steroid nucleus. There are many forms of gonane, but only a few occur naturally in living organisms. Some common forms include 5α-gonane and 5β-gonane.

Estrane Estrane is a C18 steroid derivative, with a gonane core. ''Estrenes'' are estrane derivatives that contain a double bond, with an example being nandrolone. ''Estratrienes'' (estrins) are estrane derivatives that contain three double bonds, for i ...

androstane Androstane is a C19 steroidal hydrocarbon with a gonane core. Androstane can exist as either of two isomers, known as 5α-androstane and 5β-androstane. File:androstane.png, 5α-Androstane File:androstane 5beta.png, 5β-Androstane Pharmacolog ...

, and

pregnane Pregnane, also known as 17β-ethylandrostane or as 10β,13β-dimethyl-17β-ethylgonane, is a C21 steroid and, indirectly, a parent of progesterone. It is a parent hydrocarbon for two series of steroids stemming from 5α-pregnane (originally all ...

are derivatives of gonane with additional methyl or ethyl groups attached to certain carbon positions. The term gonane is also used to describe a group of

progestin A progestogen, also referred to as a progestagen, gestagen, or gestogen, is a type of medication which produces effects similar to those of the natural female sex hormone progesterone in the body. A progestin is a '' synthetic'' progestogen. ...

s that are similar to

levonorgestrel Levonorgestrel is a hormonal medication used in a number of birth control methods. It is combined with an estrogen to make combination birth control pills. As an emergency birth control, sold under the brand names Plan B One-Step and Julie, ...

but have a slightly different structure than other hormones like estranes.

Significance

Gonane is a significant chemical compound in the family of

s because its structure comprises four hydrocarbon rings fused together, consisting of three cyclohexane units and one cyclopentane, which is often referred to as the "steroid nucleus" and serves as the parent compound for steroids. The discovery of gonane and its role as a steroid nucleus has been fundamental in understanding the structure and function of various

hormones. The numbering of steroid rings is determined based on the skeletal structure of gonane, providing a framework for the classification and identification of different steroids.

Usage of the term

The term gonane is also used to refer to a group of

s that are carbon 18-homologated 19-nortestosterone derivatives including

and its analogues. This term is used in this way in order to distinguish them from

estrane Estrane is a C18 steroid derivative, with a gonane core. ''Estrenes'' are estrane derivatives that contain a double bond, with an example being nandrolone. ''Estratrienes'' (estrins) are estrane derivatives that contain three double bonds, for i ...

s, which are also 19-nortestosterone derivatives.

Structure

Gonane is a

tetracyclic Tetracyclics are cyclic compound, cyclic chemical compounds that contain four fused ring (chemistry), rings of atoms, for example, Tröger's base. Some tricyclic compounds having three fused and one tethered ring (connected to main nucleus by ...

with no double bonds. It is formally the parent compound of the

s, hence it is called the "steroid nucleus". Some important gonane derivatives are the

steroid hormone A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Wit ...

s, characterized by

methyl group In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated a ...

s at the C10 and C13 positions and a

side chain In organic chemistry and biochemistry, a side chain is a substituent, chemical group that is attached to a core part of the molecule called the "main chain" or backbone chain, backbone. The side chain is a hydrocarbon branching element of a mo ...

at the C17 position. Because gonane has six centers of chirality, it has 64 (2⁶) theoretically possible

stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

s, that differ on the position of the lone hydrogens at carbons 5, 8, 9, 10, 13 and 14 in the direction perpendicular to the mean plane of the carbons. However, only a few of these stereoisomers occur in living organisms. The most common are 5α-gonane and 5β-gonane.

File:Gonane alpha.png, 5α-Gonane File:Gonane beta.png, 5β-Gonane File:AB-trans-Gonan.svg, 5α-Gonane, side-perspective view File:AB-cis-Gonan.svg, 5β-Gonane, side-perspective view

Variants

(C18) is the 13β-methyl variant of gonane,

(C19) is the 10β,13β-dimethyl variant of gonane, and

(C21) is the 10β,13β-dimethyl, 17β- ethyl variant of gonane.

References

Polycyclic nonaromatic hydrocarbons Steroids Tetracyclic compounds {{Steroid-stub