1. Department of Chemistry, Section of Organic Chemistry and Biochemistry, University of Ioannina, Ioannina GR-45110, Greece, Department of Chemistry, University of Florence, Via G. Capponi 7, 50121 Florence, Italy, Department of Chemistry, Université Paris 7Denis Diderot, 2 Place Jussieu, 75251 Paris Cedex 05, and Bruker (UMR 50), Buroparc 1, 3 Avenue du Général de Gaulle, 91090 Lisses, France