Triethylamine → (S)-1-[2-t-Butoxycarbonylamino-3-(3,4-dichlorobenzyloxy)propionyl]-4-(2-keto-1-benzimidazolinyl)piperidine

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Reaction Steps

Triethylamine (0.28 mL, 0.20 g, 2 mmol) was added to a stirred, cooled (0° C.) mixture of (S)-2-t-butoxycarbonylamino-3-(3,4-dichlorobenzyloxy)propionic acid (prepared according to the method of Sugano. H, and Miyoshi. M, J. Org. Chem 1976, 41, 2352) (364 mg, 1 mmol), 4-(2-keto-1-benzimidazolinyl)piperidine (217 mg, 1 mmol) and bis(2-oxo-3-oxazolidinyl)phosphinic chloride (305 mg, 2 mmol) in dichloromethane (10 mL) and the mixture was stirred at room temperature for 1h. Aqueous sodium hydrogen carbonate (saturated, 40 mL) and water (10 mL) were added and the mixture was extracted with dichloromethane (3×50 mL). The combined organic fractions were washed with aqueous citric acid (10%, 2×50 mL), aqueous sodium hydrogen carbonate (saturated, 2×50 mL) and brine (50 mL), dried (MgSO4) and the solvent was evaporated under reduced pressure. The residue was purified by flash column chromatography on silica gel, eluting with CH2Cl2 /MeOH (99:1) to give the title compound as a colorless foam (318 mg, 56%). m/e (ES+) 563 (MH+).

Provenance & Evidence