Affiliation: | 1. Department of Organic Chemistry, University of Geneva, 30 quai Ernest Ansermet, 1211 Geneve 4 (Switzerland), Fax: (+41)?223‐793215;2. School of Chemistry, The University of Nottingham, Nottingham NG7 2RD (United Kingdom), Fax: (+44)?115‐951‐3564 |