The enhancement in diastereocontrol observed upon ring opening of the β-lactone diastereomers was investigated through DFT calculations at the M06-2XSMD/def2-TZVP//M06-2XSMD/def2-SVP level using Gaussian16. The ring-opening of substrate diastereoisomers (3R,4R)-7 and (3S,4R)-8 with morpholine as a nucleophile were modelled, with calculations performed in CH2Cl2 solvation, in line with the initial experimental conditions that gave a thermodynamic ratio of β-lactone diastereoisomers in 70:30 dr (Scheme 1A) and gave the β-hydroxyamide products in 88:12 dr after ring-opening (Scheme 2B). CH2Cl2 was chosen due to its properties as a non-coordinating solvent, avoiding complexities arising from solvents that can accept hydrogen-bonds, which cannot be described accurately with only a continuum dielectric model. The enrichment in diastereocontrol observed upon ring-opening reflects a DyKAT process as the stereocontrol transitions from thermodynamic equilibrium of the β-lactone diastereoisomers to kinetic selectivity to achieve the β-hydroxyamide products in high dr. Calculation of the Gibbs free energies of the β-lactone diastereoisomers (3R,4R)-7 and (3S,4R)-8 resulted in a computed thermodynamic ratio of 63:37 (DrG = 0.3 kcal/mol, Figure ) that is in close agreement to the observed 70:30 dr. Consistent with the epimerization control experiments described above, under the basic reaction conditions it is assumed that diastereoisomers 7 and 8 rapidly interconvert by in situ epimerization due to the acidity of the β-lactone C(3)-H, contributing to the enrichment during the subsequent nucleophilic addition step.