epsilon-Caprolactam and nylon-6 oligomers were synthesized from 4-pentene-1-amine and/or 3-pentene-1-amine and carbon monoxide using CO2(CO)(8) as catalyst. The results show that the volatile fraction of the product mixture is composed of epsilon-caprolactam, 3-methyl-2-piperidinone and 3-ethyl-2-pyrrolidinone, while the solid residue mainly consists of nylon-6 oligomers. The addition of excess PEt3 as ligand can significantly improve the regioselectivity, to epsilon-caprolactam. Using 3-pentene- 1-amine as starting material leads to the same results as 4-pentene-1-amine due to rapid C=C bond isomerization. (C) 2003 Elsevier B.V. All rights reserved.