Cesium carbonate → 4-[4-((S)-1-{tert-butoxycarbonyl-[2-(2-chloro-5-methoxy-4-nitro-phenyl)-ethyl]amino}-ethyl)phenyl]-piperazine-1-carboxylic acid tert-butyl ester

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Reaction Steps

A solution of [(S)-1-(4-bromo-phenyl)-ethyl]-[2-(2-chloro-5-methoxy-4-nitro-phenyl)-ethyl]-carbamic acid tert-butyl ester (0.66 g, 1.17 mmol), N-Boc piperazine (0.44 g, 2.34 mmol), cesium carbonate (0.96 g, 2.92 mmol) and devphos (46.1 mg, 0.117 mmol) in 1,4-dioxane (5 mL) was degassed with argon. Pd2(dba)3 (0.054 g, 0.058 mmol) was added and the mixture heated to reflux for 3 hours under an argon atmosphere. The mixture was allowed to cool to room temperature, diluted with water (30 mL) and extracted with EtOAc (3×30 mL). The combined organic extracts were washed with brine, dried (Na2SO4) and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using 20% EtOAc in hexane to give the title compound (0.33 g, 46%).

Provenance & Evidence