N-Acyl derivatives of proline and 2-piperidinecarboxylic acid (pipecolic acid) were synthesized in moderate yield from N-acyl unsaturated cyclic amines through cobalt- catalyzed isomerization–carboxylation under hydroformylation conditions in the presence of H 2 O. A possible mechanism for the process is discussed which is related to that of the amidocarbonylation (cobalt-catalyzed formation of N-acyl α-amino acid from aldehyde, ...