An alternative synthesis of 17β‐hydroxy‐7α‐methyl‐19‐nor‐17α‐pregn‐5(10)‐en‐20‐yn‐3‐one (Org OD 14)

The title compound (4) was prepared starting from 17β,19‐dihydroxyandrosta‐4,6‐dien‐3‐one 17,19‐diacetate (5). Copper‐catalyzed conjugate addition of methylmagnesium iodide gave, after hydrolysis, 17β,19‐dihydroxy‐7α‐methylandrost‐4‐en‐3‐one (8a), which was converted by oxidation and deacylation into 7α‐methylestr‐5(10)‐ene‐3,17‐dione (11). Selective protection of the 3‐keto group as the dimethyl acetal, followed by ethynylation and deacetalization, gave the desired product 4. The 7β‐methyl adduct, a by‐product in the Grignard reaction, was removed after the oxidation step. Its structure was confirmed by an independent synthesis of the 7β‐methyl‐19‐aldehyde 9b.