Sodium hydride → 1alpha,3beta-Bis(tert-butyldimethylsilyloxy)-17-(4-triethylsilyloxy-4-methylpentyloxymethyl)androsta-5,7,16-triene

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Reaction Steps

To a solution of 1α,3β-bis(tert-butyldimethylsilyloxy)-17-(hydroxymethyl)androsta-5,7,16-triene (200 mg, 0.367 mmol), sodium hydride (60% in oil, 45 mg, 1.125 mmol) and 15-crown-5 (80 mg, 0.363 mmol) in tetrahydrofuran (1 ml), was added 1-bromo-4-methyl-4-(triethylsilyloxy)pentane (220 mg, 0.745 mmol) at room temperature, followed by reflux under heating for 1 hour. The reaction solution was diluted with ethyl acetate, followed by the dropwise addition of water under cooling with ice and washing with saturated brine. The organic layer was dried over anhydrous magnesium sulfate. After distilling off the solvent under reduced pressure, the thus obtained residue was purified by column chromatography (hexane:ethyl acetate=15:1) to give the titled compound (278.7 mg, quant.) as a colorless oil.

Provenance & Evidence