Synthesis of tricyclic pyrano[2,3-e]isoindolin-3-ones as the core structure of stachybotrin A, B, and C

The substituted tricyclic pyrano[ 2,3-e] isoindolin-3-ones 2 and 3, as the core structure of stachybotrin A, B, and C (1a-c), have been regioselectively synthesized for the first time by a short route which involved Mannich reaction and Claisen rearrangement.