Gold-catalyzed dual C-C bond cleavage of biphenylenes bearing a pendant alkyne at ambient temperature.

We report a catalytic skeletal rearrangement of biphenylenes with a pendant alkyne moiety at room temperature by a cationic gold catalyst, which involves the cleavage of two bonds: the C-C bond of biphenylene and the C(sp)-C(sp2 or sp3) bond. Experimental and theoretical studies revealed that the reaction mechanism included π-activation of the alkyne, ring expansion and 1,2-carbon shift.

Regioselective Activation of a Sterically More Hindered C-C Bond of Biphenylenes Using an Alkene as Both a Directing Group and a Reaction Moiety.

The Rh-catalyzed intramolecular reaction of 1-(2-vinylaryl)-substituted biphenylenes was used to construct a dihydrobenzo[b]fluoranthene skeleton. This transformation was achieved by regioselective C-C bond cleavage of a sterically more hindered biphenylene site by using alkene as both a directing group and a reaction moiety. Furthermore, we measured and analyzed the photophysical properties of the new multicyclic fused compounds.