The Concept of Allopolarization. Effects of Substituents on the Reactions of Ambifunctional Anions

The chemistry of ambifunctional anions is of great importance in organic preparations. Planning of syntheses requires a set of rules correlating structure and selectivity. The concept of allopolarization permits a description of substituent effects on kinetically controlled reactions: the change in selectivity is a function of the change in polarity of the ambifunctional anions. The relative charge density P = l x /l y serves as “polarity index”; X and Y are the potential sites of reaction. An attempt is made to illustrate the utility of this principle by means of examples taken from various classes of compounds.