Hydrochloric Acid → methyl 2-(6,6-dimethyl-4,5,6,7-tetrahydro-1H-indazol-3-yl)indole-6-carboxylate

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Reaction Steps

To a solution of 1-tert-butyl 6-methyl 2-(1-tert-butoxycarbonyl-6,6-dimethyl-4,5,6,7-tetrahydro-1H-indazol-3-yl)indole-1,6-dicarboxylate (39 g, 75 mmol) in a mixed solvent of methanol (180 ml) and tetrahydrofuran (120 ml) was added dropwise 2 N aqueous sodium hydroxide solution (149 ml, 298 mmol) under ice-cooling over 15 min, and the mixture was stirred for 15 min. Then, 1 N hydrochloric acid was added dropwise to adjust the pH to 5. The precipitated crystals were collected by filtration, washed with water, and dried under reduced pressure to give the title compound (23 g, yield 97%).

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