Sulfuric Acid → ethyl 5,6,7,8-tetrahydro-11-chloro-8-methoxy-4H-azocino [3,2,1-hi]indole-2-carboxylate

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Reaction Conditions

Reaction Steps

The ethyl 5,6,7,8-tetrahydro-11-chloro-8-hydroxy-4H-azocino[3,2,1-hi]indole-2-carboxylate (1.90 g, 6.17 mmol) obtained in Example 23, (a) was added to a mixture of methanol (19 ml) and concentrated sulfuric acid (1.89 g) which had been cooled to 0° C. The reaction mixture was heated to 40° C. and stirred for 1 hour. The reaction mixture was poured into ice water and extracted twice with ethyl acetate, and the extract solution was washed twice with a 5% aqueous sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure and the resulting residue was purified by a silica gel column chromatography (eluent: ethyl acetate/n-hexane=1/99) to obtain 1.96 g of ethyl 5,6,7,8-tetrahydro-11-chloro-8-methoxy-4H-azocino-[3,2,1-hi]indole-2-carboxylate as a colorless oil.

Provenance & Evidence