Total syntheses of (±)-frondosin C and (±)-8-epi-frondosin C via a tandem anionic 5-exo dig cyclization-Claisen rearrangement sequence

Microwave-assisted anionic 5-exo dig cyclization-Claisen rearrangement sequence has been investigated as a convenient ‘one-pot’ route to fused cycloheptanoid ring systems. This process was used as the key transformation to construct the tetracyclic framework of frondosin C. Subsequent manipulation of the core allowed the first total syntheses of (±)-frondosin C and (±)-8-epi-frondosin C in a combined overall yield of 20.8% over 14 steps.