Cesium carbonate → tert-butyl 4-{3-[(3R)-3-({(1S)-3-tert-butoxy-1-[5-(2-{[(4-methylphenyl)sulfonyl]oxy}ethoxy)pyridin-3-yl]-3-oxopropyl}carbamoyl)piperidin-1-yl]-3-oxopropyl}piperidine-1-carboxylat

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Reaction Steps

4-{3-[(3R)-3-{[(1S)-3-tert-butoxy-1-(5-hydroxypyridin-3-yl)-3-oxopropyl]carbamoyl}piperidin-1-yl]-3-oxopropyl}piperidine-1-carboxylate (200 mg, 0.34 mmol) were dissolved in N,N-dimethylformamide (39 mL). Cesium carbonate (277 mg, 0.85 mmol) and ethylene glycol bis-p-toluenesulfonate (188 mg, 0.51 mmol) were added. The mixture was stirred at room temperature for 4 hours, the addition of cesium carbonate (277 mg, 0.85 mmol) and ethylene glycol bis-p-toluenesulfonate (188 mg, 0.51 mmol) was repeated and stirring at 5° C. was continued for 17 hours. The mixture was quenched by addition of saturated aqueous ammonium chloride solution and extracted with diethyl ether and 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 chromatography on silica gel (ethyl acetate in hexane 20% to 100% followed by dioxane in ethyl acetate 0 to 60%) to yield 207 mg of tert-butyl 4-{3-[(3R)-3-({(1S)-3-tert-butoxy-1-[5-(2-{[(4-methylphenyl)sulfonyl]oxy}ethoxy)pyridin-3-yl]-3-oxopropyl}carbamoyl)piperidin-1-yl]-3-oxopropyl}piperidine-1-carboxylat.

Provenance & Evidence