Triethylsilane → (3R,4S)-4-[(R)-1-phenyl-ethylamino]-tetrahydrothiophene-3-carboxylic acid methyl ester

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Reaction Steps

A solution of crude (R)-4-(1-Phenyl-ethylamino)-2,5-dihydrothiophene-3-carboxylic acid methyl ester (2.82 g, ca. 9.1 mmol) was dissolved in trifluoroacetic acid (50 mL) and treated with triethylsilane (4.4 mL, 27.4 mmol). The mixture was stirred for 20 h, when TLC indicated residual starting material. Additional triethylsilane (1.5 mL) was added and the mixture was heated at reflux for 3 h, then was cooled and concentrated. The residue was dissolved in water and adjusted to pH 10 with 50% sodium hydroxide. The mixture was extracted with ether, and the combined organic phases were dried (Na2SO4) and concentrated. The residue was purified by flash column chromatography (15-30% diethyl ether/petroleum ether) to provide the product as a colorless oil (673 mg, 28%).

Provenance & Evidence