Triphenylphosphine → (R)-4-biphenyl-4-yl-3-{3-[1-(2-cyano-ethyl)-1H-tetrazol-5-yl]-propionylamino}-butyric acid ethyl ester

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Reaction Steps

Next, to a solution of (R)-4-biphenyl-4-yl-3-[3-(2-cyano-ethylcarbamoyl)-propionylamino]-butyric acid ethyl ester (204 mg, 0.468 mmol) in THF (10 mL) at room temperature is added Ph3P (307 mg, 1.17 mmol) and the mixture is stirred at room temperature for 10 minutes. Then to the mixture at ice bath temperature is added DIAD (0.228 ml, 1.171 mmol) and trimethylsilyl azide (0.155 ml, 1.171 mmol). The resulting mixture is slowly warmed up to room temperature and stirred for 16 hours. The reaction mixture is concentrated under reduced pressure. The obtained residue is purified by flash chromatography (silica gel, 1% to 3% EtOH/DCM) to give (R)-4-biphenyl-4-yl-3-{3-[1-(2-cyano-ethyl)-1H-tetrazol-5-yl]-propionylamino}-butyric acid ethyl ester (137 mg, 64% yield). HPLC retention time=1.61 minutes (condition C); MS=461 (m+1).

Provenance & Evidence