Reactions of diaryliodonium trifluoromethanesulfonates with low-valent ytterbium and samarium reagents

The reduction of diaryliodonium trifluoromethanesulfonates with low-valent ytterbium and samarium reagents has been studied. In the reaction of diphenyliodonium trifluoromethanesulfonate with two equimolar amounts of metallic ytterbium, benzene is formed almost quantitatively. On the other hand, iodobenzene is produced together with benzene in the reaction with divalent YbI2 or SmI2. The intermediates generated in situ by the reaction of arylphenyliodonium trifluoromethanesulfonates and metallic ytterbium are trapped with methylphenylsilane to afford diphenylmethylsilane and arylmethylphenylsilanes. With respect to the substituent effect on the aromatic ring of the arylphenyliodonium salts, electron-donating groups favor the formation of arylmethylphenylsilanes rather than diphenylmethylsilane, whereas electron-withdrawing groups induce the favorable production of diphenylmethylsilane.