Total Synthesis of (±)-Brazilin Using [4 + 1] Palladium-Catalyzed Carbenylative Annulation

Palladium-catalyzed carbene insertion
was utilized in a formal
synthesis of (±)-picropodophyllone and a total synthesis of (±)-brazilin.
All prior syntheses of brazilin have involved a Friedel–Crafts
alkylation in the key carbon–carbon bond forming events. The
palladium-catalyzed [4 + 1] reaction generates a 1-arylindane with
all of the functionalities needed for formation of the indano­[2,1-c]­chroman ring system of brazilin. The synthesis of (±)-brazilin
was achieved in 11 steps (longest linear sequence) with an overall
11% yield.