Modifications to the phosphinate group of the top-performing cinchona-phosphinate catalyst 3e demonstrated that substituting cyclohexyl with methyl substituents (3g) resulted in decreased enantioselectivity. This analog allowed us to compare with the thiophosphinate derivative 3m, which resulted in a racemic product. This provides evidence that the phosphinate group is critical for selective catalysis. The next step was to differentiate the importance of basic nitrogens on the quinoline and quinuclidine sites. This was accomplished by selectively synthesizing the N-oxides at each nitrogen and sequentially determining how each impacts asymmetric catalysis. Excess of m-CPBA in CHCl3 was used to oxidize both nitrogen sites (3p), and compound 3o was provided by subsequent selective quinuclidine N-oxide reduction (NaHSO3, HCl/acetone), while oxidation using urea hydrogen peroxide in 2,2,2-trifluoroethanol afforded 3n selectively. The quinuclidine N-oxide (3n) significantly impacted both the conversion and enantioselectivity of the transformation; this was further confirmed by a similar result observed for the doubly-blocked catalyst (3p). In contrast, the quinoline N-oxide (3o) did not impact the reaction outcome compared to the parent catalyst 3e. This result was corroborated by kinetic experiments, where we observed a perfect overlay between the quinoline N-oxide (3o) and parent catalyst (3e) reaction profiles under standard reaction conditions (orange and teal, Figure ). These studies provide crucial insights to develop a computational model for asymmetric catalysis.