Origin of (pi)-Facial Diastereoselection in Nucleophilic Addition to 1,3-Diheteran-5-ones (Heteroatom = O, S). Theoretical Evidence for the Importance of Ground-State Effects

The exterior frontier orbital extension model (the EFOE Model) strongly suggested that reversal of (pi)-facial diastereoselection in nucleophilic additions of 1,3-diheteran-5-ones (heteroatom = O or S) may originate from the unique ground-state conformation and the (pi)-facial difference in the LUMO extension around the carbonyl carbon rather than from transition state effects.