Palladium-catalyzed reaction of aryl bromides with 7-hydroxy-1,3-dienes

Palladium-catalyzed reaction of aryl bromides with 7-hydroxy-1,3-dienes proceeded in different reaction paths depending on the structure of the starting substrates. With cyclic 7-hydroxy-1,3-dienes, the reaction proceeded via insertion of the olefin into the Pd-O bond of a postulated Pd(Ar)(OR)-olefin complex to give a (η¹-allyl)palladium intermediate, which underwent η¹-η³-η¹ allylic rearrangement followed by C - C bond-forming reductive elimination to afford overall 1,4-alkoxyarylation products, while with acyclic 7-hydroxy-1,3-dienes, the reaction produced 1,2-alkoxyarylation products under the same reaction conditions. The 1,2-alkoxyarylation products resulted from insertion of the olefin into either the Pd-C or the Pd-O bond of the postulated Pd(Ar)(OR)-olefm complex followed by reductive elimination.