This section focuses on the ketone selective reactions with Cat-B, Cat-C and Cat-D. The enantioselectivity for these reactions exhibits significant variation with slight modifications in the COBI catalyst, specifically the addition of the oxy-isopropyl ( i PrO) and methyl groups on the phenyl rings. As previously concluded, the stereochemistry for these systems is governed by TS1. Introducing an i PrO group at position 2 of the phenyl ring attached to boron alters the predominant reaction pathways and reverses the ketone enantioselectivity. For the reaction with Cat-B, the pathways via the most stable RR and RS TS1 contribute to 98% of the final product composition. For reactions with Cat-C and Cat-D, TS1 structures with a SR/SS configuration are lower in ΔG ‡ than RR/RS TS1 structures. As opposed to Cat-B, reaction systems with Cat-C and Cat-D are more flexible and we obtained multiple stable SR TS1 with a ΔΔG ‡ difference of less than 1.4 kcal mol -1 compared to the global minimum (Figure .A), which all contribute to the major product of the reaction, S ketone. The low-energy SR TS1s share similar geometries. The subtle conformational differences include different fused ring geometry and rotation of the i PrO group (SI Section 4.B).