Strategy to Synthesize Kingianin: Biomimetic and Non-Biomimetic Approaches

Kingianins are complex pentacyclic natural products isolated from the bark of Endiandra kingiana. This article reviews synthetic routes for kingianins and their analogues. The reports of five research groups are grouped in biomimetic and non-biomimetic approaches, featuring the use of Diels-Alder and [2+2] ketene cycloaddition reactions. The most recent research by Six, Azmi et al. reported the utilisation of [2+2]-ketene cycloaddition of key precursors for the synthesis of bicyclo[ 4.2.0]octanes as key precursors of kingianins. This research demonstrates the advantages of ketene chemistry by synthesising precursors. With this achievement, we look forward to extending this method to the synthesis of additional bicyclo[4.2.0]octane analogues to achieve the total synthesis of kingianins.