Acetic Anhydride → 4-(2-Acetoxy-ethyl)-4-(3,5-di-tert-butyl-4-hydroxy-phenylsulfanyl)-piperidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

To 4-(3,5-di-tert-butyl-4-hydroxy-phenylsulfanyl)-4-ethoxycarbonylmethyl-piperidine-1-carboxylic acid tert-butyl ester (Ex. 1a, 510 mg, 1 mmol) in 4 mL of THF was added dropwise 1 M LiAlH4 solution (4 mL, 4 mmol) over a period of 15 min. The reaction was stirred for 1 h and then quenched with saturated NH4Cl solution (30 mL). The mixture was extracted with Ethyl acetate (40+20 mL) and the combined organic phase was dried over Na2SO4 and concentrated under reduced pressure. The residue was dissolved in 8 mL of dichloromethane. Triethylamine (300 mg, 2.9 mmol) and DMAP (10 mg) were added followed by dropwise addition of Ac2O (205 mg, 2 mmol). The reaction mixture was stirred for 3 h and then diluted with Ethyl acetate (40 mL). The mixture was washed with 1 N HCl (2×30 mL) and water (50 mL) and dried over Na2SO4. Chromatography (2-20% Ethyl acetate/hexanes) afforded 4-(2-acetoxy-ethyl)-4-(3,5-di-tert-butyl-4-hydroxy-phenylsulfanyl)-piperidine-1-carboxylic acid tert-butyl ester as a clear oil (420 mg, 82%). ESI/CI-MS m/z 506 ([M−H]−).

Provenance & Evidence