3-HALOCYCLOHEXANONES - TORSION ANGLE CHANGES AFTER CATION-CARBONYL COMPLEXATION DICTATE THE FACIAL SELECTIVITY IN REACTIONS WITH NUCLEOPHILES - AN AB-INITIO INVESTIGATION

The geometrical changes that take place after complexation of the carb onyl oxygen of 3-halocyclohexanones with prototypical cations such as H+ and Li+ were calculated using ab initio MO methods at 6-31G level. The torsion angle changes interpret rationally the experimentally know n axial preference of the 3-eq-derivatives and the axial preference (p redicted from transition state calculations) of the 3-ax-species. (C) 1997 Elsevier Science Ltd.