Progress toward the Total Synthesis of (+)-Aldosterone: Synthesis of the A−D Rings

Synthesis of the A−D rings of the cortical hormone (+)-aldosterone is described. The key step incorporates a chiral tether in a type 2
intramolecular Diels−Alder reaction that establishes the absolute configuration of four contiguous asymmetric centers. This approach provides
an efficient route for either enantiomer of the steroid skeleton.