1. Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K., DSM Research, P.O. Box 18, 6160 MD Geleen, The Netherlands, Millennium Pharmaceuticals Research and Development Ltd., Granta Park, Great Abington, Cambridge CB1 6ET, U.K., SABIC Europe, Research & Development, P.O. Box 319, 6160AH Geleen, The Netherlands, DSM Elastomers, Global R&D, P.O. Box 1130, 6160 BC Geleen, The Netherlands, and School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD...