Rhodium(I)-Catalyzed Carboacylation/Aromatization Cascade Initiated by Regioselective C-C Activation of Benzocyclobutenones

Described here is the first example of a rhodiumcatalyzed carboacylation/aromatization cascade of a C=O bond by C-C activation. In this transformation, a reactive rhodaindanone complex is regioselectively generated and adds across a C=O bond with subsequent elimination, thus providing a unique strategy to access a multisubstituted benzofuran scaffold. A diverse range of benzofuran analogues were obtained in good yields. Mechanistic studies show a tricyclic lactone was a viable intermediate. Application of this methodology to the total synthesis of C13-deOH-viniferifuran and C13-deOH-diptoindonesin G was achieved.