Electronic effects in the regiochemistry of the alkenylsilyl radical cyclizations

Abstract

The intramolecular reaction of alkenylsilyl radicals has been studied by MINDO/3. Partitioning of the total energy into local contributions is used to analyse the different effects competing in exo–endo cyclization. The change in the regioselectivity of the dimethylpent-4-enylsilyl and but-3-enylsilylmethyl radical with respect to the hex-5-enyl radical has been studied. The reversal in the regioselectivity of the silyl radical is due to an enthalpy factor caused by electronic effects.