gem-Disubstituent effect:: Theoretical basis and synthetic applications

An overview of the theoretical basis and both synthetic and biochemical applications of the gem-disubstituent effect is given. Several theories to explain the source of this rate-enhancing effect are described with their differences and similarities. In most cases, there is agreement that the origin of the gem-disubstituent effect may vary somewhat depending on the system being analyzed. Nevertheless, there is little doubt that the beneficial effect of the introduction of a geminal group can be found in many cyclizations.