1. Research Center, Novartis Vaccines and Diagnostics, Via Fiorentina 1,
53100 Siena, Italy
2. Department
of Organic and Industrial
Chemistry, University of Milan, Via G.
Venezian 21, 20133 Milan, Italy
3. Department of Chemistry, University of Guelph, 50 Stone Road East, Guelph, ON,
Canada N1G 2W1