Cesium carbonate → Tert-butyl 4-(3-((R)-3-(((S)-3-(tert-butoxy)-3-oxo-1-(4-(2-(tosyloxy)ethoxy)phenyl)propyl)carbamoyl)piperidin-1-YL)-3-oxopropyl)piperidine-1-carboxylate

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Reaction Steps

270.0 mg (0.46 mmol) 4-(3-{(R)-3-[(S)-2-tert-butoxycarbonyl-1-(4-hydroxy-phenyl)-ethylcarbamoyl]-piperidin-1-yl}-3-oxo-propyl)-piperidine-1-carboxylic acid tert-butyl ester were dissolved in 17.7 ml N,N-dimethylformamide. 449 mg (1.38 mmol) cesium carbonate and 255.3 mg (0.69 mmol) ethylene glycol bis-p-toluenesulfonate were added. The mixture was stirred at room temperature for 20 hours and concentrated. The remainder was taken up with saturated ammonium chloride solution and ethyl acetate. The aqueous phase was extracted with 3×20 ml ethyl acetate. The extracts were dried over sodium sulfate and concentrated. Chromatography over 10 g silica gel (dichloromethane/ethanol 100/0-90/10) gave 227 mg (63%) tert-butyl 4-{3-[(3R)-3-({(1S)-3-tert-butoxy-1-[4-(2-{[(4-methylphenyl)sulfonyl]oxy}ethoxy)phenyl]-3-oxopropyl}carbamoyl)piperidin-1-yl]-3-oxopropyl}piperidine-1-carboxylate which were purified by HPLC:

Provenance & Evidence