The ring-closing step which determines the enantioselectivity of the reaction was also studied by means of DFT calculations (Figure , upper part). In this step, the Cu(II)-coordinated enol produced by the nucleophilic addition of nitrone and BCB connects its electronegative carbon to the electrophilic carbon of imine to form the BCHep scaffold. The Gibbs free energy of the transition state leading to (S)-3a (TS-S) is 1.7 kcal/mol lower than that leading to (R)-3a (TS-R), resulting in the major product with (S)-configuration, which agrees with the experimental observations. To understand the origin of the energy difference between the two transition states, independent gradient model based on the Hirschfeld partition (IGMH) was employed to analyze the weak interaction . As shown in Figure (lower part), both transition states have multiple CH-π interactions between the bisoxazoline ligand and substrate. However, TS-S displays a greater number and stronger intensity of CH-π interactions (highlighted by red circles) compared to TS-R, indicating that enantioselectivity is primarily governed by non-covalent interactions. In summary, we have established an enantio-and regio-selective method for the construction of chiral BCHeps through Cu(II)-catalyzed asymmetric cycloaddition of BCBs with nitrones. The reaction featured with mild condition, high yield, high selectivity, and broad substrate scope. The success of the reaction hinges on the activation of BCB by bisoxazolin-coordinated Cu(II) catalyst, which was verified by DFT calculations. Computational chemistry revealed that the origin of enantioselectivity arises from non-covalent interactions between the ligand and substrate, offering insights for constructing other types of saturated bridged bicyclic bio-isosteres of arenes. Future works will be focusing on the application of this catalytic system to the structurally divergent synthesis of bicyclic skeletons.