The oxidation of the A-secolanosterol derivative 3-nitrilo-3,4-secolanosta-4(30),8-diene (IV) by mercuric acetate has produced the aromatic compound A-seco-1,2,3-trisnorlanosta-4(30),5(10),6,8-tetraene (VIII). When the cyanide group in (IV) was replaced by CO₂H, CO₂Me, or CONH₂, the reaction did not occur. The aromatisation reaction also failed if the isopropenyl group was reduced [as in (IX)] or when there was no double bond in ring B [as in (XII)].