Enantioselective electrocatalytic oxidation of racemic sec-alcohols using a chiral 1-azaspiro[5.5]undecane-N-oxyl radical

Article abstract of DOI:10.1016/S0040-4039(99)01325-8

Nitroxyl radical (6S,7R,10R)-4-acetylamino-2,2,7-trimethyl-10-isopropyl- 1-azaspiro[5.5]-undecane-N-oxyl reveals a reversible redox peak in cyclic voltammetry at + 0.62 V vs. Ag/AgCl. A preparative electrocatalytic oxidation of racemic sec-alcohols on the nitroxyl radical yielded mixtures of 51.4 - 63.9 % ketones and 36.1 - 48.6 % alcohols by 10 h of electrolysis. The current efficiency and turnover number of the reactions were 85.6 - 87.9 % and 20.6 - 25.6, respectively. The enantiopurity of the remaining (R)-isomers was 50 - 70 % and the S values as a selective factor was 4.1 - 4.6.