Aryltrimethylstannane Cation Radical Fragmentation Selectivities That Depend on Codonor: Evidence for Reactions from Heterodimer Cation Radicals.

ABSTRACT

The aryl/methyl fragmentation selectivities for the photooxidations of phenyltrimethylstannane and (4-methylphenyl)trimethylstannane by 1,2,4,5-tetracyanobenzene in acetonitrile were found to depend on the codonor used to generate the stannane cation radical intermediates. The aryl/methyl fragmentation selectivities for phenyltrimethylstannane and (4-methylphenyl)trimethylstannane varied by factors of 26 and 5.6, respectively, depending on the structures of the codonors. The fragmentation selectivities could be correlated with the oxidation potentials of the codonors and their steric bulk. The results can be interpreted by the intermediacy of heterodimer cation radicals formed between the stannane cation radicals and the neutral codonors, which thereby affect the fragmentation selectivities.