title: The polyphosphoric acid-catalyzed ring opening of 4,5-epoxy-3-oxo steroids. IV. The synthesis of 17alpha-hydroxy-4-ethylthiopregn-4-ene-3,20-dione and its analogs.
mesh_terms: D011278:Pregnanes / Q000138:chemical synthesis*; D013057:Spectrum Analysis
chemical_list: D011278:Pregnanes