Preferential oxidative addition in mixed iodo/bromo quinquephenylenes

Article abstract of DOI:10.1016/j.tet.2014.04.001

A Suzuki reaction of a diiodo monobromo quinquephenylene with an aryl boronic acid is described. With PEPPSI-IPr as catalyst the threefold coupling product is mainly obtained although only two equivalents of the boronic acid are used. This shows that the intramolecular palladium transfer is favored over the common iodo/bromo selectivity. Performing the reaction with other Pd systems shows that the product distribution is strongly catalyst dependent.