KO(t)Bu as a Single Electron Donor? Revisiting the Halogenation of Alkanes with CBr(4) and CCl(4)

The search for reactions where KO(t)Bu and other tert-alkoxides might behave as single electron donors led us to explore their reactions with tetrahalomethanes, CX(4), in the presence of adamantane. We recently reported the halogenation of adamantane under these conditions. These reactions appeared to mirror the analogous known reaction of NaOH with CBr(4) under phase-transfer conditions, where initiation features single electron transfer from a hydroxide ion to CBr(4). We now report evidence from experimental and computational studies that KO(t)Bu and other alkoxide reagents do not go through an analogous electron transfer. Rather, the alkoxides form hypohalites upon reacting with CBr(4) or CCl(4), and homolytic decomposition of appropriate hypohalites initiates the halogenation of adamantane.