Total synthesis of the latrunculins

The total syntheses of (+)-latrunculin A (1) and (+)-latrunculin B (2), two architecturally novel toxins isolated from the Red Sea sponge Latrunculia magnifica (Keller), have been achieved via highly convergent and stereocontrolled routes (longest linear sequences, 16 and 12 steps, respectively). Formal syntheses of scalemic latrunculins C (3) and M (5) also derive from the construction of 2. Central features of the unified synthetic strategy include the aldol reaction of aldehyde (-)-12 with methyl ketone (-)-13, a novel acid-catalyzed reorganization-equilibration of ortho ester (-)-11, and Mitsunobu macrolide cyclization