Sulfuric Acid → (5R,8S,10S,13S,14S)-10,13-Dimethyl-1,4,5,6,7,8,10,12,13,14,15,16-dodecahydro-3H-cyclopenta[A]phenanthrene-3,17(2H)-dione

Participants

Reaction Conditions

Reaction Steps

To a solution of compound 1.1 (26.0 g, 85.4 mmol) in DCM (520 mL) was added concentrated sulfuric acid (7.53 g, 76.8 mmol) over 15 minutes under an inert atmosphere at 10° C. The temperature was raised to 25° C. and the resulting solution was stirred for 2 h. At this point no more starting material remained as evidenced by TLC. The reaction was quenched by the addition of 10% aqueous NaHCO3 solution (200 mL). The layers were separated and the aqueous layer was extracted twice with DCM (2×100 mL). The organic layers were combined and washed sequentially with water (100 mL) and saturated brine solution (100 mL). The organic phase was then dried over Na2SO4 (75 g) and filtered. The filtrate was evaporated under vacuum to provide compound 1.2 (23.0 g, 94%) as an off-white solid. This product was used “as is” in the next step without further purification.

Provenance & Evidence