Pyridine → methanesulfonic acid 2-((R)-4-benzyloxycarbonylamino-4,5,6,7-tetrahydroindazol-1-yl)-ethyl ester

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Reaction Steps

To a solution of (R)-[1-(2-hydroxy-ethyl)-4,5,6,7-tetrahydro-1H-indazol-4-yl]-carbamic acid benzyl ester (755 mg, 2.40 mmol) and pyridine (1.45 mL, 18.0 mmol) in dichloromethane was added methanesulfonyl chloride (1.40 mL, 18 mmol) dropwise at 0° C. The mixture was warmed to room temperature and stirred for 6 hours. The resulting mixture was poured into ice (10 g). The organic layer was then separated and washed with 0.1 N hydrochloric acid and saturated sodium bicarbonate, dried over sodium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography (10% methanol in dichloromethane) to afford methanesulfonic acid 2-((R)-4-benzyloxycarbonylamino-4,5,6,7-tetrahydroindazol-1-yl)-ethyl ester (880 mg, 90%) as a white solid. MS calcd. for C18H23N3O5S 393, obsd. (ESI+) [(M+H)+] 394.

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