Viability of Nonclassical Carbocations Proposed as Intermediates in the Biosynthesis of Atiserene, Beyerene, Kaurene, and Trachylobane Diterpenes.

The results of quantum-chemical calculations aimed at assessing the viability of nonclassical carbocations proposed to be involved in the biosynthesis of atiserne, beyerene, kaurene, and trachylobane diterpenes are presented. While the proposed edge-protonated structure is much lower in energy than the proposed face-protonated structure, neither is predicted to be a viable intermediate energetically. [ABSTRACT FROM AUTHOR]