1. Center for Heterocyclic Compounds, Department of Chemistry; University of Florida; Gainesville FL 32611-7200 USA
2. Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy; Zagazig University; Zagazig 44519 Egypt
3. Department of Organic Chemistry, College of Pharmacy; Misr University for Science and Technology; Al-Motamayez District, P.O. Box 77 Egypt
4. Chemistry Department; King Abdulaziz University; Jeddah 21589 Saudi Arabia