Stereoelectro nic intera ction effects on the conforma tional properties of cis-۵-tert-bu tyl-۲-phosphinoyl-۱,۳-dioxane, -dithian e and –diselenane

Conformational equilibria in alicyclic molecules has been studiedin the p ast several years. Theoretical treatm ents of cy cloalkanes have also provided val ues in reaso nable agre ement with experimental. The knowledge about conformati onal properties of hetero cycli comp ounds should be of very general interest since saturated h eterocyclic compounds comprise a large segment of orga nic and inorganic che mistry and are quite widespread in nature, e.g. in alkaloids, carbohy drates, and plant growt h regulators, among othe r compound s.It is well known that the ste reoelectronic interactions could play an important role on the confo rmational pr operties of heterocycli c compound s There is a stereoelectronic preference for conformations in which the best dono r lone pair is antiperiplanar to the be st acceptor bond. Praly and Lemieu x have stressed that the anomeric effects (AE ) must be considered as the differ ence between the sum of the endo- and exo-anomeric effects (e.g. endo-AE and exo -AE) in the equatorial conformer and the same sum fo r the axial conformer. Also, they have suggested that there is no any endo-AE in the equatorial conforme r, therefore, it is exclusively stabilized by exo-AE interactions Anomer ic effect ex o-AEeq _ ˱exo-AEax endo-AEax

کلیدواژه ها:

cis-۵ -tert-butyl- ۲-phosphinoyl-۱ ، ۳-dioxa ne ، anomeric effects ، stereoelectronic intera ctions ، molecular modeling