1. Department of Discovery Chemistry and Department of Cardiovascular Disease, Pharmacia, 700 Chesterfield Parkway W, Chesterfield, Missouri 63017, Office of Science and Technology, Chemical Science Division, Pharmacia, 800 Lindbergh Boulevard, Creve Coeur, Missouri 63167, Department of Pharmaceutical Sciences, Pharmacia, Skokie, Illinois, and Department of Chemistry, University of Missouri, St. Louis, Missouri