Cesium carbonate → tert-butyl 4-{3-[(3R)-3-({(1S)-3-methoxy-1-[3-(2-{[(4-methylphenyl)sulfonyl]oxy}ethoxy)phenyl]-3-oxopropyl}carbamoyl)piperidin-1-yl]-3-oxopropyl}piperidine-1-carboxylat

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Tert-butyl-4-{3-[(3R)-3-{[(1S)-1-(5-hydroxypyridin-3-yl)-3-methoxy-3-oxopropyl]carbamoyl}piperidin-1-yl]-3-oxopropyl}piperidine-1-carboxylate (example 4e, 80 mg, 0.15 mmol) was dissolved in N,N-dimethylformamide (20 mL). Cesium carbonate (120 mg, 0.37 mmol) and ethylene glycol bis-p-toluenesulfonate (81 mg, 0.22 mmol) were added. The mixture was stirred at room temperature for 2 hours, quenched by addition of saturated aqueous ammonium chloride solution and extracted with ethyl acetate. The combined extracts were washed with brine and dried over sodium sulfate. The solution was concentrated under reduced pressure and the residue was purified by preparative thin layer chromatography on silica gel (ethyl acetate in dichloromethane 60%) to yield 67 mg of tert-butyl 4-{3-[(3R)-3-({(1S)-3-methoxy-1-[3-(2-{[(4-methylphenyl)sulfonyl]oxy}ethoxy)phenyl]-3-oxopropyl}carbamoyl)piperidin-1-yl]-3-oxopropyl}piperidine-1-carboxylat.

Provenance & Evidence