According to our deuterium labelling experiments shown in Figure , the enantio-determining step was revealed as the hydrometallation step, i.e., the migratory insertion of Ni(II)H to produce IN7 (E). A comparison of TS5-S and TS5-R was conducted and is shown in Figure . TS5-S was thermodynamically disfavoured, which could be attributed to the repulsion between the aryl substituent group in the ligand and the alkyl group in the amide protecting group. It can also be seen from the quadrant diagram obtained perpendicular to the Ni-ligand direction that the ligands are mainly distributed in quadrants II and IV. For TS5-S, the alkyl chain has steric repulsion with the ligand in quadrant IV, making it relatively unstable. The feasibility of TS5-R resulted in the major S-configuration products.