a
University of Heidelberg, Department of Organic Chemistry, INF 270, D-69120 Heidelberg, Germany, EU
b
University of Bonn, Kekulé-Intitute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany, EU
E-mail: dirk.menche@uni-bonn.de
;
Tel: +49 (0)228-732653