It is important to note that the product of this reaction is inverted with respect to the stereochemical center attached to the metal.
The second step can proceed with either the nucleophilic attack of the halide ion on the α-carbon of the alkyl group or reductive elimination, both of which result in the inversion of stereochemistry.
For instance the following example shows the nucleophilic abstraction of H+ from an arene ligand attached to chromium.
If the methyl group is replaced with ethyl, the reaction proceeds 70 times slower which is to be expected with a SN2 displacement mechanism.
In the second step a ketone is added for the nucleophilic abstraction of the silylium ion and the hydrogen is left on the metal.
The mechanism follows a tetrahedral intermediate which results in the methyl ester and the reduced palladium complex shown.
The following year a similar mechanism was proposed where oxidative addition of an aryl halide followed by migratory CO insertion and is followed by nucleophilic abstraction of the α-acyl by MeOH.
The intramolecular attack of these linear acyl derivatives gives rise to cyclic compounds such as lactones or lactams.