Hydrochloric Acid → 2-t-Butoxycarbonyl-9-methylcarbamoylmethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole

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Reaction Steps

A 10 ml portion of tetrahydrofuran solution containing 0.62 g (1.80 mmol) of 2-t-butoxycarbonyl-9-methoxycarbonylmethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole was mixed with 2 ml of aqueous solution containing 0.22 g (5.40 mmol) of sodium hydroxide and stirred overnight at room temperature. This was acidified by adding 1 N hydrochloric acid and extracted with chloroform. The extract was washed with water and dried (Na2SO4), and then the solvent was removed by evaporation under a reduced pressure. The thus obtained residue was dissolved in 12 ml of acetonitrile, and the solution was mixed with 557 mg (2.70 mmol) of N,N-dicyclohexylcarbodiimide and 365 mg (2.70 mmol) of 1-hydroxybenzotriazole and stirred at room temperature for 2 hours. The reaction solution was cooled to 0° C., mixed with 2 ml of 40% methylamine aqueous solution and again stirred at room temperature for 30 minutes. The insoluble matter was removed by filtration, the solvent was removed by evaporation under a reduced pressure and then the resulting residue was purified by a silica gel column chromatography (130 cc; elution by chloroform-methanol=30:1) to obtain 542 mg of the title compound (88% in yield).

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