Addition of Benzyl Radicals to Alkenes: The Role of Radical Deformation in the Transition State

Nonplanar radical centers in the transition state are responsible for the slow rate of addition of benzyl and para ‐substituted benzyl radicals to monosubstituted and 1,1‐disubstituted alkenes. This was shown by ESR spectroscopy, since the para ‐substituents do not significantly affect the rate of the addition. The conclusion is in agreement with the calculated transition‐state structures for the addition of simple alkyl radicals to alkenes.