An improved protocol for aerobic oxidation of acetals to esters catalyzed by N-hydroxy phthalimide (NHPI) and lipophilic Co(II) complexes

In this work the effect of lipophilization of Co(II) ions on the rate of the aerobic oxidation of acetals to esters in the presence of N-hydroxy phthalimide (NHPI) was investigated. The catalysts that were used in this work are Co(OAc)(2) (1a), Co(OCOC5H11)(2) (1b), Co(OCOC6H5)(2) (1c), Co(OCOC9H19)(2) (1d), Co(OCOC17H35)(2) (1e). It has been found that among the described Co(II) salts, both 1b and 1c were better suited than the other cobalt carboxylates in catalyzing of aerobic oxidation of acetals in the presence of NHPI. The probable role of the carboxylate ligands were also briefly discussed. (C) 2004 Published by Elsevier B.V.