摘要：

It is recognized that there are obvious difficulties and limitations associated with an attempt to apply mechanistic criteria to many diverse electrophilic addition and 1,3-dipolar cycloaddition reactions of carbon-carbon double bonds. It would be desirable to determine the lower and upper limits of each criterion, to better define the essential parameters which affect each criterion, to discuss the exceptions in more detail, and to more critically consider the variable nature of the activated complex owing to its position along the reaction coordinate. However, owing to space limitations, incomplete theories, and a dearth of pertinent experimental observations, the data and discussions are presented in the pithy form above. It would also be desirable to further explore the contributions and influence of heats of hydrogenation, ionization potentials (Table LXVI), spectroscopic excitation energies, and strain energies on the relative rates of additions to carbon-carbon double bonds. It is clear from the above relative reactivity data that there is promise of establishing objective criteria or sets of criteria to help decide whether electrophilic addition or 1,3-dipolar cycloaddition reactions to carbon-carbon double bonds involve cyclic processes or noncyclic processes, and to help ascertain the ring size of cyclic activated complexes.

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