[NH2:1][C:2]1[CH:10]=[C:9]([C:11]([O:13][CH3:14])=[O:12])[CH:8]=[C:7]2[C:3]=1[CH:4]=[CH:5][NH:6]2.[H-].[Na+].[CH2:17](I)[CH3:18].[ClH:20]>CN(C=O)C.CCOCC>[ClH:20].[NH2:1][C:2]1[CH:10]=[C:9]([C:11]([O:13][CH3:14])=[O:12])[CH:8]=[C:7]2[C:3]=1[CH:4]=[CH:5][N:6]2[CH2:17][CH3:18]To a solution of methyl 4-amino-1H-indole-6-carboxylate (D201) (900 mg, 4,74 mmol, 1 equiv) in DMF (25 ml) at room temperature was added NaH (60% dispersion in mineral oil, 200 mg, 5 mmol, 1.05 equiv) and after 15 min ethyl iodide (400 μl, 5 mmol, 1.05 equiv). The resulting mixture was stirred for 30 min then most of the solvent was removed in vacuo. The residue was diluted with AcOEt and the organic phase was washed with a 2N aqueous HCl solution, dried over MgSO4 and concentrated in vacuo. Purification of the residue by flash chromatography on silica gel (iso-hexane/AcOEt: 1/1) gave an oil which was diluted with Et2O and treated with a 4N HCl solution in Et2O. The precipitate obtained was filtrated off to give methyl 4-amino-1-ethyl-1H-indole-6-carboxylate hydrochloride salt (D202) (800 mg, 66%) as a white solid. [M+H]+=219.0, RT=2.50 min.
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