Some studies in the biosynthesis of terpenes and related compounds.

Cyclic terpenes as a class of natural products display a bewildering array of structural types. Well over a hundred different carbon frameworks have been detected so far, many new substances are being currently added to an already impressive list of compounds, and even several representatives of the long-sought group of sesterterpenes have at last made their appearance on the chemical scene14. In spite of this almost inexhaustible prodigality of Nature, it had been recognized at an early stage that the biological formation of cyclic terpenes can be traced back to the operation of a unifying and, in principle, rather simple biosynthetic scheme5. In the light of present knowledge three main phases can be discerned. In the first phase (Figure 1), regularly built pyrophosphate esters of aliphatic terpene alcohols are formed through successive elongation of a basic