1. Institute for Organic Chemistry and BMWZ Leibniz Universität Hannover Schneiderberg 38 30167 Hannover Germany
2. Instituto de Química de São Carlos Universidade de São Paulo CP 780, CEP 13560-970 São Carlos SP Brazil
3. Department of Chemistry & BioDiscovery Institute University of North Texas 1155 Union Circle 305220 Denton Texas 76203 USA