Methanol → 1alpha,3beta-bis(tert-butyldimethylsilyloxy)-20(S)-hydroxypregna-5,7,16-triene

Participants

Reaction Conditions

Reaction Steps

The (1α,3β)-1,3-bis((tert-butyl(dimethyl)silyl)oxy)pregna-5,7,16-trien-20-one synthesized in Example 24 (45.0 g) was dissolved in toluene (240 ml) and then cooled to −20° C., followed by stirring for 30 minutes. Borane-dimethylsulfide complex (22.9 ml) was added to the resulting solution at −20° C. and stirred for 5 minutes. A 1M toluene solution of (R)-2-methyl-CBS-oxazaborolidine (22.9 ml) was further added to the solution at −20° C. and stirred for 1 hour. Methanol was added to the reaction mixture, which was then extracted with ethyl acetate. The extracted solution was dried over anhydrous sodium sulfate and evaporated under reduced pressure to remove the solvent. The resulting residue was purified by silica gel column chromatography (liquid phase: hexane/ethyl acetate=9/1) to give the titled compound (23.3 g, yield 89%).

Provenance & Evidence