In our initial studies, we surveyed phosphine oxides and found that it was difficult to achieve high enantioselectivity (Table ). In contrast, diphenyl phosphine (2a) gave promising results with Cu. Therefore, we choose diphenyl phosphine (2a) and cyclopropene 1a as model substrates. For the convenience of handling and analysis, the cyclopropyl phosphine products were oxidized with sulfur to generate the corresponding phosphine sulfides. In previous studies using copper catalysis, Yin's group demonstrated the superiority of Taniaphos ligands for the Cu-catalyzed alkylation of secondary phosphines. 9g However, Taniaphos ligands were ineffective in this cyclopropene hydrophosphination (Table , entry 7). Instead, we found the DuPhos ligand family most promising (Table , entry 8,9). Higher selectivity was correlated with larger R-substituents on the ligand (92% yield, 98:2 er) (vide infra). The addition of base is necessary to promote the formation of Cu-phosphido (Table ). With further tuning of the reaction stoichiometry, we developed a convenient and practical protocol for the asymmetric coupling of phosphines and cyclopropenes under Cu catalysis. In parallel, we identified a related protocol using Pd catalysis that is complementary to Wang's. While the Wang group reported that cyclopropene 1a does not transform under with their standard conditions (5 mol% Pd2dba3, 11mol% (R,R)-QuinoxP, 1,4-dioxane, 60 °C), 4g we found that Pd(OAc)2, in the presence of (R)-SEGPHOS, provides cyclopropyl phosphine 3aa in 86 % yield with 97:3 er. With this Pd condition, we also obtained phenyl ester cyclopropyl phosphine 3la (84%, 96:4 er, >20:1 dr) and p-chloro phenyl ester cyclopropyl phosphine 3ma (68%, 94:6 er, 9:1 dr) by desymmetrizing corresponding cyclopropenes (see SI 2B for details).