1. Electrosynthesis Company, Inc., 72 Ward Road, Lancaster, New York 14086, U.S.A., Chemical Development, Antibioticos, S.p.A., Strasa Rivoltana-20090 Rodano (MI), Italy, Chemical Development, Schering-Plough Research Institute, 1011 Morris Avenue, New Jersey 07083, U.S.A., and Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, U.S.A.