Orbital symmetry conservation and frontier orbital control in the reactions of organic radical cations

Abstract

Electrocyclic ring-openings, cycloreversions, cycloadditions, and sigmatropic rearrangements of organic radical cations are discussed in terms of a simple qualitative theory, based on orbital symmetry conservation or frontier orbital interactions. Special emphasis is placed on the photo-chemical reactions of the radical cations, numerous examples of which have recently been discovered experimentally. The theoretical models are in good general accord with the apparent facility with which radical cation rearrangements and fragmentations have been observed to take place, and provide some detailed predictions, especially with respect to stereochemistry, for further experimental testing.