Chiral discrimination in electrocatalytic oxidation of (R)- and (S)-1-phenylethanol usinga chiral nitroxyl radical as catalyst

A chiral nitroxyl radical, (6R,7S,10R)-4-oxo-2,2,7-trimethyl-10-isopropyl-1 -azaspiro[5.5] undecane-N-oxyl, was used as catalyst in the electrooxidatio n reaction of (R)- and (S)-1-phenylethanol. Cyclic voltammetric studies sho wed that the catalytic current for the oxidation of (R)-1-phenylethanol is highly enhanced as compared with a very small enhancement in the oxidation current for the (S)-isomer. The (R)-isomer can be detected selectively in a mixture of (R)- and (S)-1-phenylethanol, even in the presence of an excess amount of (S)-isomer.