As expected, variation of the R group indicated that the size of this substituent can have an influence on the selectivity, with a computed reduction in selectivity for the formation of ester 7 from 4 (R = Me) to 81:19 er (DD ‡ G273 = 0.8 kcal/mol) which is qualitatively in line with the experimentally observed enantioselectivity of 90:10 er at 0 ˚C. Reaction profile for the DKR to form 14 following reference. DG273 at the level of M06-2XPCM(chloroform)/def2-TZVP//M06-2XPCM(chloroform)/def2-SVP in kcal/mol.