Triethylamine → 4-[1-(3,6-Dichloro-5-hydroxymethyl-pyrazin-2-yl)-piperidin-4-ylideneaminooxy]-piperidine-1-carboxylic acid isopropyl ester

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Reaction Steps

The crude 56c obtained in the previous step was combined with triethylamine (50 μL, 0.36 mmol) in 2 mL of THF and treated at 0° C. with ethyl chloroformate (30 μL, 0.31 mmol). The mixture was stirred at room temperature for 4 h then it was added to a stirred suspension of sodium borohydride (32 mg, 0.84 mmol) in water and the stirring was continued for 3 h. The mixture was quenched with aqueous NaHCO3 (5 mL) and water (5 mL) and extracted with EtOAc (3×5 mL). The combined extracts were dried and concentrated and the residue was purified by reparative TLC(eluent: EtOAc) to afford 56-1: LC-MS 442.0 (MH+-18), tR=7.43 (Method 2). EC50: 35 nM.

Provenance & Evidence