Hydrochloric Acid → 3-(9H-fluoren-9-ylmethoxycarbonylamino)cyclohexane-1-carboxylic Acid

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Reaction Steps

3-Aminocyclohexanecarboxylic acid (10 g, 70 mmol) was added to a solution of sodium hydrogen carbonate (7.6 g, 91 mmol) in water (100 mL). A solution of 1-[[(9H-fluoren-9-ylmethoxy)carbonyl]oxy-2,5-pyrrolidinedione (Fmoc-OSu; 28.3 g, 84 mmol) in tetrahydrofuran (200 mL) was added. The solution was stirred at room temperature overnight and then poured into 3 M HCl (200 mL). The mixture was extracted with ethyl acetate (100 mL then 50 mL) and the combined organic layers were washed with saturated brine (3×100 mL), dried (Na2SO4), filtered, and concentrated to approximately 200 mL. Crystallization occurred on concentration. The mixture was allowed to stand overnight, then the solid was filtered off, washed with ethyl acetate and dried in a vacuum oven at 55° C. to give 3-[N-[(9H-fluoren-9-ylmethoxy)carbonyl]amino]cyclohexanecarboxylic acid (14.66, 57%) as a white solid.

Provenance & Evidence