Tension between Internal and External Modes of Stabilization in Carbocations Relevant to Terpene Biosynthesis: Modulating Minima Depth via C-H···π Interactions.

Density functional theory calculations on a carbocation rearrangement relevant to the biosynthesis of the sesquiterpenoid trefolane A are described, with a focus on the viability of altering the curvature of the potential energy surface through C-H···π interactions of the sort likely to be found at the active site of a terpene synthase enzyme. These interactions are able to remove a deep minimum from a pathway to product.