Model Studies towards Diazonamide A: Synthesis of the Heterocyclic Core

As a potent anticancer agent isolated from the colonial ascidian Diazona chinensis, diazonamide A (1) represents one of the most enticing natural products isolated in recent years and a serious challenge to synthetic chemists. By utilizing a highly convergent approach, the BCDEF macrocycle 2 was constructed in only 17 linear steps based on a key intermolecular Suzuki coupling reaction to generate the C16–C18 biaryl linkage, and an intramolecular Horner–Wadsworth–Emmons (HWE) condensation to form 2 as a single atropisomer from 3.