The study of the effect of ligand enantiopurity on the product enantioselectivity revealed a linear relationship (Figure ), suggesting the involvement of a single chelating ligand L6 in the enantiodetermining step. The absolute configuration of product 3a generated under the Ni/((R,R)-L6) reaction conditions was determined to be the R configuration, as confirmed by the X-ray crystallographic analysis of derivative 5b-1 (CCDC number: 2347391). Based on the accumulated experimental evidence, two possible mechanistic pathways can be proposed for this asymmetric decarboxylative C(sp 3 )-C(sp 3 ) cross-coupling reaction: "Transmetallation (TM) First" pathway or the "Single-electron oxidative addition (SOA) First" pathway. In the SOA first pathway (Figure To elucidate the proposed mechanism and gain a deeper understanding of the enantioselectivitydetermining step, density functional theory (DFT) calculations were performed. The radical-type organozirconocene-based C(sp³)-C(sp³) cross-coupling mechanism has been previously elucidated in our previous studies . In the present decarboxylative cross-coupling system, Ni(BF4)2•6H2O was identified as the optimal nickel source. Compared to previous reaction conditions, this system did not involve any halide anion. We compared three possible Ni I complexes with different counter ions and found that the phthalimide anion (1-3, 0.0 kcal/mol) was thermodynamically more stable compared to THF (1-2, 25.0 kcal/mol) or BF4 (1-1, 25.9 kcal/mol) (Supplementary Figure ).