Imidazole → 3alpha-(t-Butyldimethylsilyloxy)-7alpha,12alpha-dihydroxy-5beta-cholan-24-oic acid

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Reaction Steps

Cholic acid, 4.08 g, is dissolved in 10 ml of dry dimethylformamide and 3.40 g of imidazole is added, followed by 3.60 g of t-butyldimethylsilyl chloride. The reaction mixture is allowed to stand overnight at room temperature. The reaction mixture is poured into water, filtered and the precipitate is washed with water. This precipitate is dissolved in 30 ml of tetrahydrofuran and 3 ml of water and 2 ml of acetic acid is added. After 6.5 hours, the solvent is evaporated and the residue chromatographed on 200 g of silica gel with 5% methanol in methylene chloride as eluent, to provide 3α-(t-butyldimethylsilyloxy)-7α,12α-dihydroxy-5β-cholan-24-oic acid, mp 145.5-148, having the following structural formula: ##STR14##

Provenance & Evidence