Antiochic acid1and its biosynthetically related polycyclic
diterpenes represent a vast multitude in the fascinating realm
of terpenoids.
1
Furthermore, they have interesting structures
and biological activities (Scheme 1).
1,2
The antiochic acid1
possessed several synthetic challenging structural features,
including multisubstituted tricyclic core, two quaternary
chiral centers, and the styrene type side chain. Although
several racemic syntheses of abietane diterpenes have been
reported,
3,4
antiochic acid1had not surrendered to any total
synthesis yet. To mimic terpenoids biosynthesis, we are
interested in using the polyene cyclization strategy for the
total synthesis of1. Herein, we reported the asymmetric total
synthesis of 1 using a bioinspired polyene cyclization
reaction.
5
This method allows the construction of tricyclic
core of1with stereochemical control of up to five chiral
centers in single step (Scheme 2).