Synthesis of Biaryls via Palladium‐Catalyzed [2+2+2] Cocyclization of Arynes and Diynes: Application to the Synthesis of Arylnaphthalene Lignans

A novel method for construction of biaryls via palladium(0)‐catalyzed [2+2+2] cocyclization of diynes and arynes was developed. By this [2+2+2] cocyclization, various arylnaphthalene derivatives, including a sterically hindered 2,2′‐disubstituted‐1,1′‐binaphthyl, can be constructed by virtue of a variety of combinations of diynes and aryne precursors. Using this [2+2+2] cocyclization as a key step, the total syntheses of natural arylnaphthalene lignans, taiwanin C, taiwanin E, and dehydrodesoxypodophyllotoxin were achieved.