1. DSM Pharmaceutical Products, Innovative Synthesis and Catalysis, P.O. Box 16, 6160 MD Geleen, The Netherlands, DSM Fine Chemicals Austria, P.O. Box 296, 4021 Linz, Austria, and Université Lille 1, Sciences et Technologie, LCOM, Equipe “Oxydation et Physico-chimie de la Formulation”, CNRS UMR 8009, Bât. C6, 59655 Villeneuve d’Ascq Cedex, France