The basic molecular structure of a steroid includes four rings—three
six-membered and one five-membered—which are built entirely of carbon
atoms. The biological function of a steroid depends on the groups attached to
these rings. Diosgenin, for instance, has two additional rings (highlighted
here in red). To modify diosgenin's molecular structure to the desired
cortisone, our virtual chemist needs to perform a series of chemical reactions.