[Cl:1][C:2]1[CH:3]=[C:4]2[C:8](=[C:9]([C:11]([O:13][CH3:14])=[O:12])[CH:10]=1)[N:7]([CH2:15][CH:16](OC)[O:17]C)[CH:6]=[C:5]2[CH3:21].Cl>C1COCC1>[Cl:1][C:2]1[CH:3]=[C:4]2[C:8](=[C:9]([C:11]([O:13][CH3:14])=[O:12])[CH:10]=1)[N:7]([CH2:15][CH:16]=[O:17])[CH:6]=[C:5]2[CH3:21]To a stirred solution of methyl 5-chloro-1-(2,2-dimethoxyethyl)-3-methyl-1H-indole-7-carboxylate (909 mg, 2.9 mmol) from Step C above in THF (20 ml) was added 2N HCl (20 ml). The mixture was heated to 60° C. for 4 h. The solvent was evaporated and the residue purified by column chromatography (silica gel, 70:30 hexanes/ethyl acetate) to afford methyl 5-chloro-3-methyl-1-(2-oxoethyl)-1H-indole-7-carboxylate (690 mg, 89%) as a yellow solid: MS (ESI+) m/z 266 (M+H).
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