Alternative Routes to Tricyclic Cyclohexenes with Trinuclear Palladium Complexes

Highly symmetric all-metal aromatic Pd-3(+) complexes can catalyze the cycloisomerization of terminal 1,6-enynes and internal dienynes under mild conditions. Modification of substrates dictates the mechanism and steers the reaction toward different polycyclic frameworks, enabling the development of complex cascades. The reactivity of Pd(4/3) complexes is complementary to that of mononuclear Pd(0) and Pd(II) ones.