Starting with a zerovalent palladium species and a substrate containing a leaving group in the allylic position, the Tsuji–Trost reaction proceeds through the catalytic cycle outlined below.
First, the palladium coordinates to the alkene, forming a η -allyl-Pd Π complex. The next step is oxidative addition in which the leaving group is expelled with inversion of configuration and a η -allyl-Pd is created (also called ionization). The nucleophile then adds to the allyl group regenerating the η -allyl-Pd complex. At the completion of the reaction, the palladium detaches from the alkene and can start again in the catalytic cycle.