Potassium Hydroxide → (R)-5-(3-(benzyloxycarbonylamino)piperidin-1-yl)-8-cyano-9H-carbazole-2-carboxylic acid

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Reaction Steps

Step 3 A solution of (R)-ethyl 5-(3-(benzyloxycarbonylamino)piperidin-1-yl)-8-cyano-9H-carbazole-2-carboxylate (0.67 g, 1.349 mmol) and potassium hydroxide (0.379 g, 6.75 mmol) in 10:1 ethanol-water (33 mL) was heated at 85° C. for 2 h. The mixture was cooled to rt and the precipitate was collected by filtration, washed with ethanol and dried to afford (R)-5-(3-(benzyloxycarbonylamino)piperidin-1-yl)-8-cyano-9H-carbazole-2-carboxylic acid as a yellow solid (130 mg, 21%). Mass spectrum m/z 469.1 (M+H)+. (R)-5-(3-aminopiperidin-1-yl)-8-cyano-9H-carbazole-2-carboxylic acid was also isolated from filtrates (150 mg, 33%). Mass spectrum m/z 335.2 (M+H)+.

Provenance & Evidence