First stereoselective total synthesis of FD-594 aglycon.

Stereocontrolled access to the hexacyclic core of FD-594 has been achieved. The key steps include the intramolecular S(N)Ar reaction for construction of the densely functionalized xanthone skeleton, the stereoselective lactone cleavage using a chiral nucleophile to induce the axial stereochemistry, and the SmI(2)-mediated pinacol cyclization for the stereocontrolled conversion of axially chiral biaryl dialdehyde into the corresponding trans diol.