Steroids are biologically very important compounds. They are made up of more that seventeen carbons. The structure of Steroid is comprised of a fused cycloalkane ring system. The simplest steroid and the main skeleton of all steroids is Gonane.
Gonane is made up of four cycloalkane rings i.e. tetracyclic hydrocarbon ring structure. Among these four rings 3 are cyclohexanes (designated as A, B and C) and one is cyclopentane (Designated as D). These four rings fuse to form a cyclopentaperhydrophenanthrene.
The Nucleus (Gonane) of steroids along with some derivatives are shown below,