ON THE ORIGIN OF PI-FACIAL DIASTEREOSELECTIVITY IN ADDITION-REACTIONS OF CYCLOHEXANE-BASED SYSTEMS

The unsymmetric electron density distribution of the LUMOs of the carbonyl π‐bond of cyclohexanones (in the picture C is left, O right) is the reason for preferred axial attack (a) of these compounds by nucleophiles. If the ketones are substituted in the 3‐position by electronegative substituents (e.g. halogens), this tendency is enhanced still further. The authors have been able to demonstrate this by quantum mechanical ab‐initio calculations. (Figure Presented.) Copyright © 1991 by VCH Verlagsgesellschaft mbH, Germany