Acetaldehyde → 2,3,4-trifluoro-6-(1-hydroxyethyl)-5-pivaloylamino-O-tetrahydropyranylphenol

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Reaction Conditions

Reaction Steps

3.60 g (10.9 mmol) of the above 2,3,4-trifluoro-5-pivaloylamino-O-tetrahydropyranylphenol was dissolved in 50 mL of tetrahydrofuran, 14 mL of a 1.6 M solution of n-butyl lithium in n-hexane was added dropwise to the solution at an internal temperature of -60° C. or below, the mixture was warmed to -35° C. and cooled again to -60° C. or below. About 2 mL of acetaldehyde was added thereto in a gaseous condition and the mixture was stirred for 20 minutes. Water was added to the reaction solution, the mixture was warmed to room temperature and extracted once with ethyl acetate. The organic layer was washed once with water and once with an aqueous saturated solution of sodium chloride and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=5:1-3:1) to give 2.45 g of a mixture of diastereomers of 2,3,4-trifluoro-6-(1-hydroxyethyl)-5-pivaloylamino-O-tetrahydropyranylphenol (yield: 60%).

Provenance & Evidence