Intramolecular Alder-Rickert Reaction for Phthalide Construction: Total Synthesis of the Proposed Structure of Kerriin A

Phthalides are prevalent structural motifs in bioactive natural products, yet their efficient synthesis remains challenging. Herein, we report an intramolecular Alder-Rickert cascade strategy for the rapid assembly of the phthalide framework, enabling the simultaneous construction of both the γ-lactone and benzene rings. This approach was applied to the synthesis of the proposed structure of kerriin A in 7 steps from commercially available starting materials, with an overall yield of 11%. Comparison of the spectroscopic data of the synthetic material with those reported for the natural product revealed clear discrepancies, suggesting that the reported structure of kerriin A may require revision and is likely a positional isomer.