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Abstract. The title compound (4) was prepared starting from 17P,19-dihydroxyandrosta-4,6-dien-3--one 17,Ig-diacetate (5). Copper-catalyzed conjugate addition of methylmagnesium iodide gave, after hydrolysis, 17P, 19-dihydroxy-7a-methylandrost-4-en-3-one @a), which was converted by oxidation and deacylation into 7a-methylestr-5( lO)-ene-3,17-dione (1 1). Selective protection of the 3-keto group as the dimethyl acetal, followed by ethynylation and deacetalization, gave the desired product 4. The 7P-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 7P-methyl-19-aldehyde 9b.

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