The Electrophilic and Radical Behavior of α-Halosulfonyl Systems

The purpose of this review is to provide an informative backdrop to the susceptibility of α-halosulfonyl compounds to nucleophilic displacement and free radical chemistry. The coverage includes both inter- and intramolecular transformations. While α-halosulfones were initially recognized to exhibit quite low reactivity under S_N2-conditions, this perceived disadvantage can be overcome by making recourse to a polar aprotic solvent such as dimethylformamide. The possible role of steric, electronic, and conformational effects is addressed and shown to differ significantly from the many intramolecular anionic cyclizations that do not exhibit significant kinetic retardation. The data will also show that carbon-carbon bond forming processes under radical conditions are notably clean and efficient reactions. Where ring closures are involved, the adherence to conventional conformational and steric guidelines is shown to be reliable within reasonable limits. These features are expected to contribute to the increased adaptation of electrophilic α-sulfonyl radicals to the solution of synthetic problems.

nucleophilic displacement - field effects - intramolecular eliminations - electrophilic radicals - sulfones - sulfonamides