A Concise Route to Dihydrobenzo[b]furans: Formal Total Synthesis of (+)-Lithospermic Acid.


A sequence of Sonogashira coupling, Pd(II)-catalyzed carbonylative annulation, and benzofuran redn. (Mg, MeOH, NH4Cl) provides a convergent and modular synthetic route to trans-2-aryl-2,3-dihydrobenzo[b]furan-3-carboxylates, which share structural features with numerous biol. active natural products. This versatile strategy was applied to the formal total synthesis of the anti-HIV natural product (+)-lithospermic acid (I).

Organic Letters