Palladium-catalyzed coupling reactions of biphenylene with olefins, arylboronic acids, and ketones involving C-C bond cleavage

The reaction of biphenylene with olefins in the presence of Pd(PPh3)(4) lea ds to tire catalytic formation of products arising from addition of the vin ylic C-H bond across the carbon-carbon bond of biphenylene. Weak acids are found to promote the reaction. Under similar conditions, arylboronic acids lead to products in which an aryl group adds across the C-C bond. Ketones a nd nitriles possessing or-hydrogens are found to also add across the C-C bo nd of biphenylene, resulting in the formation of new biaryl derivatives.