Computational studies were conducted using Gaussian16 to rationalize the diastereomeric ratios of products resulting from allylations to 20. The B3LYP 14 density functional with the 6-31G(d,p) basis set was selected for geometry optimizations and free energy calculations for each conformer due to its demonstrated applicability to systems analogous to it. Calculations reveal that formation of the proton-chelate 22 is energetically favorable and that the chelate can adopt two halfchair-like conformations 23b and 24b (Figure ). Assuming that the facial trajectory of nucleophilic attack is best described by Fürst-Plattner rules with the formation of twist-boat products energetically unlikely, the magnitude of diastereoselectivity observed is best represented by the overall energy difference between conformers 23b and 24b of the proton chelate.