1. Eastchem, School of Chemistry, North Haugh, University of St Andrews, St Andrews, Fife, UK, Fax: +44‐1334‐463808
2. University of Amsterdam, Institute of Molecular Chemistry, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands
3. DSM Pharmaceutical Products‐Innovative Synthesis & Catalysis, P. O. Box 18, 6160 MD Geleen, The Netherlands