To a suspension of cis-4-(2-chloro-5-nitropyridin-4-ylamino)cyclohexanecarboxylic acid (5 g, 16.68 mmol) in toluene (111 mL) was added 2-(benzyloxy)ethanol (7.62 g, 50.0 mmol), cesium carbonate (16.31 g, 50.0 mmol), and 18-crown-6 (6.61 g, 25.02 mmol). The resulting mixture was purged with argon and stirred at 75° C. overnight. The mixture was allowed to cool to RT and diluted with EtOAc to about 150 mL total volume and washed sequentially with brine (2-150 mL), aqueous NH4Cl (2-150 mL) and water (150 mL). The organic phase was collected, dried over sodium sulfate and concentrated under reduced pressure. The residue was suspended in EtOH (111 mL) and thionyl chloride (36.5 mL, 500 mmol) was added dropwise via syringe. The reaction mixture was stirred at RT for 16 hours. The mixture was concentrated to ⅓ volume and diluted with DCM (150 mL). The organic portion was washed with aqueous NaHCO3 (100 mL), dried over sodium sulfate and concentrated. The residue was purified by silica gel chromatography (10-50% EtOAc/Hexanes) to afford cis-ethyl 4-(2-(2-(benzyloxy)ethoxy)-5-nitropyridin-4-ylamino)cyclohexanecarboxylate (5.6 g, 76% yield). MS m/z=444.2 [M+H]. Calc'd for C23H29N3O6: 443.2.
