Androsta-1,4-diene-3,17-dione → (8'R,9'S,10'R,13'S,14'S)-10',13'-dimethylspiro[1,3-dioxolane-2,17'-7,8,9,11,12,14,15,16-octahydro-6H-cyclopenta[a]phenanthrene]-3'-one

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Reaction Steps

To a solution of androsta-1,4-dien-3,17-dione (1, 10.0 g) in benzene (600 ml) and ethylene glycol (90 ml) was added toluene-p-sulfonic acid monohydrate (0.3 g), and the solution was refluxed for 8-10 hours with a Dean-Stark apparatus for collecting water. The reaction mixture was cooled to room temperature, diluted with ethyl acetate and washed thoroughly with water, dilute sodium bicarbonate solution, water and finally with brine. The organic phase was dried over anhydrous magnesium sulfate, filtered and the organic solvent removed by rotary evaporator. The resultant solid was crystallized from methanol to give 17,17-ethylenedioxyandrosta-1,4-dien-3-one (2) as a white crystalline solid in 95% yield (11.0 g).

Provenance & Evidence