Structure elucidation of new compounds from acidic treatment of the progestins gestodene and drospirenone

Gestodene acidic treatment afforded a single rearrangement product, namely 13-β-ethyl-18,19-dinorpregna-4,14,16-trien-3,20-dione 3, which was originated through HCl-catalyzed Rupe rearrangement. Drospirenone acidic treatment yielded two epimeric lactones by addition of HCl to the 6β,7β-cyclopropane ring, namely 7β-(chloromethyl)-15β,16β-methylene-3-oxo-17β-pregn-4-ene-21,17-carbolactone 4 and 7β-(chloromethyl)-15β,16β-methylene-3-oxo-17α-pregn-4-ene-21,17-carbolactone 5. The structure of the compounds was assessed by spectroscopic and crystallographic methods.