Catalytic Asymmetric Total Synthesis of Hedyosumins A, B, and C

The
first and asymmetric total synthesis of hedyosumins A, B, and C was
accomplished in 13–14 steps from simple starting materials.
The essential tools that allow us to access the tetracyclic skeleton
include an organocatalytic [4 + 3] cycloaddition reaction, an intramolecular
aldol condensation, and an intramolecular carboxymercuration/demercuration
enabled lactonization. A CBS-catalyzed asymmetric reduction was employed
to boost the ee of the synthetic natural products to an excellent
level. This synthesis established the absolute configurations of hedyosumins
A, B, and C.