Triphenylphosphine → (S)-3-[4-acetylamino-2-((R)-2-indazol-1-yl-1-methyl-ethoxy)-benzenesulfonylamino]-4,4-diethoxy-butyric acid tert-butyl ester

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Reaction Steps

A mixture of 0.25 g (0.54 mmol) (S)-3-(4-acetylamino-2-hydroxy-benzenesulfonylamino)-4,4-diethoxy-butyric acid tert-butyl ester, 0.096 g (0.54 mmol) (S)-2-indazol-1-yl-1-methyl-ethanol, 0.285 g (1.08 mmol) triphenylphosphine, and 40 mL dry tetrahydrofuran was stirred at room temperature. Diethyl azodicarboxylate 0.2 mL (1.08 mmol) was added dropwise and the resulting yellow solution was stirred 18 h at room temperature. TLC analysis indicated complete reaction. The reaction mixture was concentrated in vacuo to give a deep yellow oil. The product ether was purified over silica eluting with ethyl acetate to 9:1 ethyl acetate:methanol to yield 0.298 g (0.48 mmol, 89%) of (S)-3-[4-acetylamino-2-((R)-2-indazol-1-yl-1-methyl-ethoxy)-benzenesulfonylamino]-4,4-diethoxy-butyric acid tert-butyl ester as a colorless foam.

Provenance & Evidence