Cingestol

Cingestol , also known as 17α-ethynylestr-5-en-17β-ol, is a steroidal progestin of the 19-nortestosterone group that was never marketed. It was synthesized in 1969 and was developed in the 1970s by Organon as a low-dose, progestogen-only contraceptive, but in 1984, was still described as "under investigation". The drug is an isomer of lynestrenol with the double bond between C5 and C6.

Chemistry

Synthesis

The chemical synthesis was originally reported in 1969.
FGI of nandrolone benzoate into its corresponding enol acetate gives. The reduction of this with sodium borohydride gave a mixture of two epimeric alcohols, the beta-alcohol predominating. Halogenation of this alcohol gave the chloride. Lithium in ammonia cleaved of the halogen, the ester was also removed during this step, PC149159696. Oxidation with Jones reagent gave the ketone PC140376320. Favorskii reaction should smoothly form cingestol in a single step.