A partial synthesis of 13-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-17-ol (desogestrel) based upon intramolecular oxidation of an 11β-hydroxy-19-norsteroid to the 18->11β-lactone

Article abstract of DOI:10.1002/recl.19881070406

A partial synthesis of the 13-ethyl-18-norsteroid desogestrel is reported.The key step in the synthesis is the intramolecular oxidation of 11β-hydroxyestr-5-ene-3,17-dione cyclic bis(1,2-ethanediyl acetal) 3 with Pb(OAc)4 and iodine to 3,3:17,17-bis<1,2-ethanediylbis(oxy)>-11β-hydroxyestr-5-en-18-oic acid γ-lactone 2.The 13-COOH group was then converted into a 13-ethyl group by a Grignard reaction with methylmagnesium bromide followed by Wolff-Kishner reduction of the 13-acetyl group thus formed.