Catalytic [2 + 2 + 2] and Thermal [4 + 2] Cycloaddition of 1,2-Bis(arylpropiolyl)benzenes

We have determined that a cationic rhodium(I)/Segphos complex catalyzes an enantio- and diastereoselective intermolecular [2+2+2] cycloaddition of 1,2-bis(arylpropiolyl)benzenes with various monoalkynes at room temperature to give axially chiral 1,4-teraryls possessing an anthraquinone structure in good yields with good enantio- and diastereoselectivities. We have also determined that a thermal intramolecular [4+2] cycloaddition of 1,2-bis(arylpropiolyl)benzenes proceeds at 60 degrees C to give aryl-substituted naphthacenediones in moderate to good yields.