1. Department of Organic Chemistry, Wageningen Agricultural University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands (J.-W.d.K., M.C.R.F., A.d.G.)
2. Research Institute for Agrobiology and Soil Fertility, P.O. Box 14, 6700 AA Wageningen, The Netherlands (J.-W.d.K., H.J.B.)
3. Institute of Organic Chemistry, Hamburg University, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany (W.A.K.)