1,1'-Carbonyldiimidazole → 2-t-Butoxycarbonyl-9-dimethylcarbamoylmethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole

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Reaction Steps

The 2-t-butoxycarbonyl-9-carboxymethyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole (1.65 g, 5.0 mmol) obtained in the above step (1) was dissolved in methylene chloride (30 ml), and the solution was mixed with carbonyldiimidazole (0.81 g, 5.0 mmol), stirred at room temperature for 30 minutes, mixed with 2 M dimethylamine-THF solution (3 ml, 6.0 mmol) and further subjected to 1 hour of the reaction. The reaction solution was concentrated, the resulting residue was dissolved in ethyl acetate (50 ml), washed with water and dried with anhydrous sodium sulfate, and then the solvent was removed by evaporation under a reduced pressure. By adding diisopropyl ether (30 ml) to the resulting residue, 1.71 g of the thus precipitated title compound (4.8 mmol, 96% in yield) was obtained as crystals.

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