Is a 1,4-Alkyl Shift Involved in the Biosynthesis of Ledol and Viridiflorol?

Results from density functional theory computations indicate that a 1,4-alkyl shift proposed as part of the carbocation cyclization/rearrangement leading to ledol, viridiflorol, and related sesquiterpenes is not energetically viable. Instead, a previously proposed mechanism that avoids such a shift is greatly preferred.