Ketyl radical reactions

The comparison of the values of Ee0 for reactions of ketyl radicals with peroxides with those for reactions R1R2C 0H + R2C(0) show that the reaction of the ketyl radical with peroxide occurs with sufficiently higher Ee0 (see Table 6.30). Obviously, this is the result of strong additional repulsion in the nonlinear polyatomic transition state of the ketyl radical reaction with peroxide... 

Rate Constants of Ketyl Radical Reactions with Dioxygen... 

Rate Constants of Ketyl Radical Reactions with Dioxygen Radical Solvent T (K) (L mol-1 s-1) Ref. 

The high preference for reaction at the exo-face is, however, strongly influenced by substituents at C-7 and only endo attack is found in pinacol formation of camphor57. The intermediate ketyl radicals recombine exclusively to form the endo-endo-addition product. Furthermore, the reaction also shows high enantioselectivity as the ketyl radicals derived from (+)-camphor recombine much faster with a second ( + )- instead of a (-)-camphor ketyl radical. Reaction of a racemic mixture, therefore, proceeds to yield only one racemic product. 

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