Computational and Synthetic Investigation of Cationic Rearrangement in the Putative Biosynthesis of Justicane Triterpenoids

Abstract

Abstract A biomimetic cationic structural rearrangement of the oleanolic acid framework is reported for the gram‐scale synthesis and structural reassignment of justicioside E aglycone. The mechanism of the putative biosynthetic rearrangement is investigated with kinetic, computational, and synthetic approaches. The precursor to rearrangement was accessed through two strategic advancements: (1) synthesis of a 1,3‐diketone via oxidation of a β‐silyl enone, and (2) diastereoselective 1,3‐diketone reduction to form a syn ‐1,3‐diol using SmI 2 with PhSH as a key additive.