1. Organic Pharmaceutical Chemistry, Uppsala University, Uppsala Biomedical Centre, Box 574, SE-751 23 Uppsala, Sweden, Local Discovery Research Area CNS & Pain Control, AstraZeneca R&D Södertälje, SE-15185 Södertälje, Sweden, Biovitrum AB, SE-112 76 Stockholm, Sweden, Preclinical R&D, AstraZeneca R&D Lund, SE-22187 Lund, Sweden, and Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285