1. Centre
de Recherche de Gif, Institut de Chimie des Substances Naturelles, CNRS, 91198 Gif-sur-Yvette Cedex, France
2. Laboratory
of Synthesis and Natural Products, Institute of Chemical Sciences
and Engineering, Ecole Polytechnique Fédérale de Lausanne
(EPFL), EPFL-SB-ISIC-LSPN, CH-1015 Lausanne, Switzerland