Zr. Zheng et H. Lund, ELECTROCHEMICAL REDUCTION OF O-ACYLATED ALDEHYDE CYANOHYDRINS, Journal of electroanalytical chemistry [1992], 441(1-2), 1998, pp. 221-225
Cyanohydrins of aromatic aldehydes, acylated at the hydroxyl group, ar
e reducible in aprotic medium; the base generated during the reduction
induces a rearrangement of the compound to a vicinal diketone. Thus,
O-benzoyl benzaldehyde cyanohydrin (1) is rearranged during the reduct
ion to benzil and O-acetyl benzaldehyde cyanohydrin to 1-phenylpropane
-1,2-dione; on the cyclic voltammetric curves of the acylated cyanohyd
rins the radical anion of the diketone gives an anodic peak on the rev
erse sweep and the diketone a cathodic peak on the second negative swe
ep. The reduction of the diketones occurs at a higher potential than t
hat of the O-acyl benzaldehyde cyanohydrin and the diketone is therefo
re reduced further at the potential used for the reduction of the acyl
ated benzaldehyde cyanohydrin. Thus both benzil and O-benzoyl benzalde
hyde cyanohydrin yield on reduction the same main product, benzyl phen
yl ketone; besides that, 1 gives minor amounts of benzylcyanide and be
nzoic acid. Possible reaction routes are discussed. (C) 1998 Elsevier
Science S.A.