1. Laboratorium für Organische ChemieETH Zurich Hönggerberg, HCI Vladimir-Prelog-Weg 3 8093 Zurich Switzerland
2. Dipartimento di Chimica e Chimica IndustrialeUniversità di Pisa via Moruzzi 13 56124 Pisa Italy
3. Institute of Organic ChemistryPolish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland