Compounds of the Formula I ##STR1## are nonpeptide antagonists of endothelin which are useful in treating a variety of diseasses such as elevated levels of endothelin, acute respiratory distress syndrome (ARDS), atherosclerosis, restenosis, Raynaud's phenomenon etc. The compounds are prepared by reacting an alpha-hydroxy butenolide with one or more equivalents of a suitable base, and exposing the solution to UV light.