1. Department
of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
2. Swiss Federal Institute of Technology (EPFL), Chemical Synthesis Laboratory (SB-ISIC-LSYNC), 1015 Lausanne, Switzerland
3. Institute
of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland