Removal of a protective group by electrolytic oxidation or reduction is useful
in some cases. An advantage is that the use and subsequent removal of chemical
oxidants or reductants (e.g., Cr or Pb salts; Pt– or Pd–C) are eliminated. Reductive
cleavages have been carried out in high yield at 1 to 3 V (vs. SCE), depending
on the group; oxidative cleavages in good yield have been realized at 1.5–2 V
(vs. SCE). For systems possessing two or more electrochemically labile protective
groups, selective cleavage is possible when the half-wave potentials, E1/2, are suffi
ciently different; excellent selectivity can be obtained with potential differences
on the order of 0.25 V. Protective groups that have been removed by electrolytic
oxidation or reduction are described at the appropriate places in this book; a review
article by Mairanovsky11 discusses electrochemical removal of protective
groups.12