A Promiscuous Proton in Taxadiene Biosynthesis?

Abstract

Herein we describe quantum chemical calculations on a two-step proton-transfer pathway that interconverts key intermediates in the biosynthesis of taxa-4,11-diene, a precursor of Taxol, that provides an energetically more favorable alternative to the usually proposed direct proton-transfer pathway. In effect, the bicyclic diterpene skeleton involved in this rearrangement provides a cage of three pi-bonds that surrounds a locally mobile proton. [reaction: see text]