Directionality in Formation of Small Rings by Intramolecular Nucleophilic Substitution

The formation of small rings by intramolecular nucleophilic substitution is examined with respect to the activation parameters for such processes set beside calculations of the transition structure dimension and the problem of alignment of nucleophile, electrophile and leaving group. The consequences of restraint on the leaving group trajectory are considered in the light of synthetically useful procedures involving intramolecular attack on strained rings and the often inefficient harnessing of strain in the acceleration of elimination reactions.