Affiliation: | 1. Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G.Bonchev str., bl.9, 1113 Sofia (Bulgaria), Fax: (+359)?2‐8700‐225 http://www.orgchm.bas.bg/~lantonov;2. Departement Chemie, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland) |