1. Natural Products Chemistry, Infectious Diseases, and Process Research, Merck Research Laboratories, Merck and Company, P.O. Box 2000, Rahway, New Jersey 07065, Center of Fungal Genetics, Merck Frosst Canada, Montreal, Quebec H2X 3Y8, Canada, and CIBE, Merck, Sharp & Dohme de España, S. A. Josefa Valcárcel, Madrid, Spain