1. College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 P.R. China
2. Organofluorine Chemistry Department, Institute of Organic Chemistry; National Academy of Sciences of Ukraine; Kiev-94 02660 Ukraine
3. University of Nebraska-Lincoln; Lincoln Nebraska 68526 USA
4. Department of Chemistry; Purdue University; West Lafayette Indiana 47907 USA
5. Institute of Organic Chemistry; Justus-Liebig University; Heinrich-Buff-Ring 17 35392 Giessen Germany