Cyclisation process of forming a multiple ring compound

A cyclisation process for forming a multiple ring compound, the process comprising reacting an isoprenoid compound with an acetal initiator under conditions sufficient to form the multiple ring compound, wherein the cyclisation process comprises an intramolecular cyclisation reaction of the isoprenoid compound, and

• wherein the acetal initiator is an oxygen acetal, a thioacetal or a selenoacetal having one of the following general formulas (I) or (II):
• wherein:
• A and B are independently heteroatoms selected from the group consisting of O, S and Se;
• R1 is selected from the group consisting of aliphatic, cycloaliphatic, aromatic, arylaliphatic, and arylcycloaliphatic groups, comprising from 0 to about 3 heteroatoms selected from the group consisting of N, O, S, Se and Si;
• D is an aliphatic, cycloaliphatic or arylaliphatic bridge containing from 1 to about 12 carbon atoms, completing a non-aromatic ring that includes from 0 to about 2 heteroatoms;
• and
• R2 and R3 are independently selected from the group consisting of aliphatic, cycloaliphatic, aromatic, arylaliphatic, and arylcycloaliphatic groups, comprising from 0 to about 3 heteroatoms selected from the group N, O, S, Se and Si, and wherein one of R2 and R3 may be H.