As a proof-of-concept study, we firstly focused on the Cu-catalyzed 1,3-dipolar cycloaddition of azomethine ylide 1 with methacrylonitrile 2 reported by Houk, Overman and coworkers (Figure ). They reported that the choice of phosphine ligands largely affects diastereoselectivity of the reaction. For example, whereas a 32:68 mixture of (endo)-3 and (exo)-3 was obtained when PPh3 was employed, the selectivity was improved up to 10:90 by using PCy3 as a ligand. They analyzed the origin of diastereoselectivity by DFT calculations and revealed that a steric repulsion between the nitrile group in 2 and PCy3 destabilizes the TS for the endo cycloaddition, resulting in the selective formation of the exo cycloadduct.