Conformational behaviors of 1,7-dioxa-spiro[5,5]undecane and its dithia and diselena analogs in relation to the anomeric effect: A hybrid-DFT, ab initio MO study and NBO interpretation

► The conformational properties 1,7-dioxa-, 1,7-dithia- and 1,7-diselen-spiro[5,5]undecanes (1-3) investigated. ► The calculated ΔG values between conformations A, B and C decrease from compound 1 to compound 3. ► Similar trend is observed for the calculated AEC-B, AEB-A and AEC-A values. ► The AE succeeds solely to account for conformation A preference of compounds 1-3. ► There is no a reasonably correlation between the total dipole moment and total energy differences.