Establishing the Trifluoromethylthio Radical Donating Abilities of Electrophilic SCF3-Transfer Reagents.

The recent recognition of the novel application of a few traditional electrophilic trifluoromethylthiolating reagents as SCF3 radical sources offers a remarkable new opportunity for the development of radical trifluoromethylthiolation reactions. Herein, the first trifluoromethylthio radical donating ability (Tt•DA) scale of electrophilic SCF3-transfer reagents has been developed. This scale is based on Y-SCF3 bond dissociation energies, which were obtained by density functional calculations (M06-2X). Single electron transfer is revealed to exhibit a substantial Y-SCF3 bond-weakening effect, thus significantly facilitating the SCF3 radical (•SCF3) release. The results may aid in future novel radical SCF3-transfer reagent design and new reaction development.