Lithium tri-tert-butoxyaluminohydride → (3R,5R,8S,10S,13S,14S)-3-Hydroxy-10,13-dimethyl-3,4,5,6,7,8,10,12,13,14,15,16-dodecahydro-1H-cyclopenta[a]phenanthren-17(2H)-one

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Reaction Steps

A THF solution of lithium tri-tert-butoxyaluminum hydride (1.0 M, 84.4 mL, 84.4 mmol) was added to a cold (−40° C.) solution of compound 1.2 (23.0 g, 80.4 mmol) in THF (230 mL) under an inert atmosphere. The resulting reaction mixture was stirred for 2 h. At this point the reaction was determined to be complete, as evidenced by TLC, and the reaction mixture was quenched by adding a mixture of 1N HCl (200 mL) and ethyl acetate (230 mL). The resulting two phase mixture was separated and the aqueous layer was extracted twice with ethyl acetate (2×100 mL). The organic phases were combined and washed sequentially with water (150 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 afford compound 1.3 (23.0 g) as an off-white solid. The above crude product was used “as is” in the next step without purification.

Provenance & Evidence