For the cationic pathway, our method fails to predict α selectivity for butoxy (O-nbutane) and acetyloxy (OAc), and fails to predict a mix for N-succinimide. Since we are doing a relatively limited conformational search, we have tested whether the calculations improve by performing a systematic search with up to 50,000 conformers (Table ) or a molecular dynamics (MD)-based search (Table ) but the results for these substituents do not change. In fact, a more thorough conformational search in general leads to slightly worse agreement with experiment. The better results of the more limited conformational search are most likely due to a better error cancellation since the ligand conformations are more similar in the two intermediates.