Total syntheses of wentilactones A and B, and related norditerpene dilactones.

Wentilactones A and B, two representative tetranorditerpenoid dilactones with promising antitumor activities, are synthesized for the first time. The synthesis employs 3β-hydroxydilactone 6 as a common precursor, which is derived from ( S )-Wieland-Miescher ketone, and leads easily to derivatives with various modifications on the A-ring, such as CJ-1445, asperolide B, and the unnamed natural congener 4.