Diels-Alder Reaction in Air- and Moisture-stable Zinc-containing Ionic Liquids I-Wen Sun* ( ), Shin-Yi Wu ( ), Chia-Hao Su ( ), Yu-Lin Shu ( ) and Pei-Lin Wu* ( ) Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan, ROC Diels-Alder reactions in a number of air- and moisture-stable dialkylimidazolium halide-ZnCl2 ionic liq- uids are reported. ... 51, No. 2, 2004 Sun et al. CO2C2H5 CO2C2H5 CO2C2H5 + + 1a 2a 3aa-endo 3aa-exo ...