Sodium borohydride → (20Z)-20-Formamido-3-methoxypregna-3,5,17(20)-triene-9alpha,21-diol

Participants

Reaction Conditions

Reaction Steps

Under a nitrogen atmosphere sodium borohydride (0.53 g) and lithium aluminium hydride (0.65 g) were added to a stirred solution of ethyl (20Z)-20-formamido-9α-hydroxy-3-methoxypregna-3,5,17(20)-trien-21-oate (4.85 g, prepared according to example 10), in dry tetrahydrofuran (100 ml) at 0° C. The reaction mixture was stirred at 5° C. for 2 hours, after which another 0.54 g of sodium borohydride and 0.65 g of lithium aluminium hydride were added. Stirring was continued at 5° C. for 1.5 hours, then ethanol (50 ml) was added dropwise to decompose excess reducing agent. After adding 60 ml of an aqueous solution of sodium potassium tartrate, the reaction mixture was filtered and extracted with ethyl acetate. The organic phase was washed with an aqueous sodium carbonate solution and with water, dried (MgSO4) and concentrated under reduced pressure. The residue (3.02 g) was purified by column chromatography (toluene/acetone 2/1 containing 0,1% triethylamine) to provide 1.08 g of the title compound.

Provenance & Evidence