[CH3:1][N:2]1[C:10]2[C:5](=[CH:6][C:7]([N+:11]([O-])=O)=[CH:8][CH:9]=2)[CH:4]=[C:3]1[C:14]([O:16][CH2:17][CH3:18])=[O:15].C([O-])=O.[NH4+]>[Pd].C(O)C.O>[NH2:11][C:7]1[CH:6]=[C:5]2[C:10](=[CH:9][CH:8]=1)[N:2]([CH3:1])[C:3]([C:14]([O:16][CH2:17][CH3:18])=[O:15])=[CH:4]2Alterative A. To a mixture of ethyl 1-methyl-5-nitro-1H-indole-2-carboxylate (420 g), from step (a) or commercial sources, and 10% palladium on carbon catalyst (50% wet) (42 g) in ethanol (4200 mL) was added a solution of ammonium formate (541.5 g) in demineralized water (840 mL) at between 25-35° C. over 3 hours. The mixture was stirred for 18 hours at 20° C., and then filtered, washing the solids with ethanol (2100 mL). The combined filtrate and washings were concentrated to 840 mL under vacuum at about 20° C. The resulting slurry was granulated at 5° C., filtered, washed with chilled ethanol (420 mL), and dried to give product ethyl 5-amino-1-methyl-1H-indole-2-carboxylate (316.5 g, 86%).
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