Androsta-1,4-diene-3,17-dione → 1-Methyl-androsta-1,4-diene-3,17-dione-17-ethylene ketal

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Reaction Steps

32.22 (mmol) of a 10% solution of trimethylaluminum in hexane is introduced at room temperature under nitrogen atmosphere. With stirring, 6.6 g (30 mmol)-of 2,6-di-tert-butyl-4-methylphenol is added in portions. The solution is stirred for 30 more minutes at 35° C. This thus produced solution of dimethylaluminum-2,6-di-tert-butyl-4-methylphenoxide is added at 58° C. to a solution of 9.84 g (30 mmol) of androsta-1,4-diene-3,17-dione (ADD) and 430 mg (1.5 mmol) of nickel(II)-acetylacetonate in 60 ml of ethyl acetate (acetic acid-ethyl ester). The solution is stirred for 4 more hours at a temperature of 60° C. For hydrolysis, 5 ml of water is added with cooling. The inorganic solid is filtered off and rewashed twice with 20 ml of ethyl acetate. After concentration by evaporation of the ethyl acetate phases, 17 g of crude,material is obtained, which is chromatographed on silica gel with hexane/ethyl acetate as eluent with increasing ethyl acetate portion. After concentration by evaporation of the fractions, 12.9 g of 1-methyl-androsta-1,4-diene-3,17-dione-17-ethylene ketal (28% of theory) of melting point 159° C. is obtained.

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