A catalyst consisting of Pd-2(dba)(3) + 2 XANTPhos (dba = dibenzylideneacetone, XANTPhos = 9,9-dimethyl-4,5-bis(diphenylphosphino) xanthene) in toluene catalyzes the alkoxycarbonylation of 4-penten-l-ol to form the cyclic products e-caprolactone and 2-methylvalerolactone, as well as oligocaprolactone. The conversion and selectivity observed using this catalyst is higher than that observed with other reported systems with the regioselectivity for terminal carborylation exceeding 70%. (c) 2005 Elsevier B.V. All rights reserved.