1. Department of Chemistry; Higher Teachers' Training College; University of Maroua; P.O. Box 55 Maroua Cameroon
2. Department of Chemistry; Higher Teachers' Training College; University of Yaoundé I; P.O. Box 47 Yaoundé Cameroon
3. Department of Chemistry; Faculty of Science; The University of Bamenda; P.O. Box 39 Bambili Cameroon
4. International Center for Chemical and Biological Sciences; University of Karachi; Karachi 75270 Pakistan
5. Department of Organic Chemistry; Faculty of Science; University of Yaoundé I; P.O. Box 812 Yaoundé Cameroon