Synthesis of catalysts 1 to 6. We synthesized three-site organocatalysts 1 to 4 in > 90% yields via two efficient and easy-to-handle steps of amine-thioisocyanate Michael addition and hydroboration (Figs. 1 and S1-S9, Supplementary Information). These catalysts integrate Takemoto's catalyst and a boron group in one molecular. The boron moiety is derived from the common borohydride reagent of 9-borabicyclo[3.3.1]nonane (9-BBN). The amine and thiourea groups in catalysts 1 to 3 are designed at the ortho, meta, and para positions of the benzene ring, respectively. We also synthesized catalyst (S, S)-4 bearing chiral amine and thiourea moieties to form isotactic PLA blocks given their crystallinity and enhanced mechanical properties. Recently, Dove, Coulembier, Taton, and co-workers reported the isoselective ROP of rac-LA using a chiral Takemoto's catalyst. In addition, bifunctional catalysts 5 and 6 were synthesized as controls.