The reaction of Wakamatsu was applied for the preparation of alpha-acetyl-aminoacids from several unsaturated substrates in very mild conditions in the presence of a cobalt-stibine-modified system in comparison to some classical cobalt-phosphine precursors. The stibine and phosphine ligands used were: triphenylstibine (TPS), o- and p-tritolylstibine (o-TTS, p-TTS), phenyl(phenylethynyl)mesitylstibine (PPEMS), phenylthienylmesitylstibine (PTMS), p-fluorophenylstibine (p-TFPS), triphenylphosphine (TPP), o- and -p-tritolylphosphine (o-TTP, p-TTP). (C) 2003 Elsevier B.V. All rights reserved.