N-bromobutanimide → HCID 14428789, compound

Participants

Reaction Steps

18.4 mg of (22R)-1α,3β,22-triacetoxycholest-5-en-25-ol (IVa1) was dissolved in 2 ml of carbon tetrachloride; the solution was refluxed under heating under argon gas atmosphere, and then 8.2 mg of N-bromo-succinimide was added to the mixture. After refluxing for 25 minutes, the mixture was cooled with ice-water, and the insoluble material was removed by filtration. The filtrate was concentrated under reduced pressure, and the residue was dissolved in 1.5 ml of xylene, and the solution was added dropwise to a refluxed solution of 1 ml of xylene and 1.5 ml of 2,4,6-collidine under argon gas stream atmosphere. After the dropping was completed, the mixture was refluxed for 10 minutes. The mixture was diluted with ethyl acetate, and the mixture was washed with 2N-hydrochloric acid, saturated aqueous sodium hydrogen carbonate, and water, successively, and dried over magnesium sulfate. The residue was dissolved in 10 ml of acetone, and after adding thereto 5 mg of p-toluenesulfonic acid, the mixture was stirred overnight under argon gas stream atmosphere under dark condition at room temperature. The reaction solution was diluted with ethyl acetate, washed with water, and dried over magnesium sulfate. The solvent was removed by distillation, and the residue was subjected to preparative thin layer chromatography (solvent: n-hexane-ethyl acetate=2:1; developing: 5 times) for purification to give 1.75 mg of (22R)-1α,3β,22-triacetoxycholest-5,7-dien-25-ol (Va1).

Provenance & Evidence