Isobutylene oxide → 1alpha,3beta-Bis(tert-butyldimethylsilyloxy)-20-hydroxy-20-methylpregna-5,7,16-triene

Participants

Reaction Conditions

Reaction Steps

A solution of 1α,3β-bis(tert-butyldimethylsilyloxy)-20-hydroxy-20-methylpregna-5,7,16-triene (49.2 mg, 0.0859 mmol), potassium hydride (35% in oil, 0.1 ml, 0.873 mmol) and dibenzo-18-crown-6 (30 mg, 0.0832 mmol) in toluene (0.2 ml) was stirred at room temperature for 3 min., 1,2-epoxy-2-methylpropane (60 mg, 0.832 mmol) was added and stirred at external temperature of 45° C. for 1.5 hours. The reaction solution was cooled with ice and water was added. The mixture was diluted with ethyl acetate, washed with saturated brine and the organic layer was dried over anhydrous magnesium sulfate. After evaporating under reduced pressure to remove the solvent, the thus obtained residue was purified by preparative thin layer chromatography (2 sheets (each 0.5 mm thickness), hexane:ethyl acetate=15:1, developed twice) to give the titled compound (10.4 mg, 19%) and 1α,3β-bis(tert-butyldimethylsilyloxy)-20-hydroxy-20-methylpregna-5,7,16-triene (18.6 mg, 38%), each as a colorless oil.

Provenance & Evidence