[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][C:7]([CH3:12])=[C:6]2[CH:13]=[O:14].[H-].[Na+].[Cl:17][C:18]1[CH:26]=[CH:25][C:21]([C:22](Cl)=[O:23])=[CH:20][CH:19]=1.C(OCC)(=O)C>CN(C)C=O.O>[Cl:17][C:18]1[CH:26]=[CH:25][C:21]([C:22]([N:8]2[C:9]3[C:5](=[CH:4][C:3]([O:2][CH3:1])=[CH:11][CH:10]=3)[C:6]([CH:13]=[O:14])=[C:7]2[CH3:12])=[O:23])=[CH:20][CH:19]=1
To a solution of 5-methoxy-2-methyl-1H-indole-3carboxaldehyde (20 g, 106 mmol) in 210 ml of dry dimethylformamide is added oil free sodium hydride (2.7 g, 111 mmol). The reaction mixture is stirred for five hours at which time it is cooled to -60° C., and freshly distilled 4-chlorobenzoyl chloride (14.4 ml, 117 mmol) is added dropwise. It is stirred for an additional 10 minutes and worked up by pouring the cold paste into cold ethyl acetate and water. The organic phase is washed once with dilute sodium bicarbonate solution, once again with water, and once with a saturated solution of sodium chloride. It is further dried with magnesium sulfate, filtered, and concentrated in vacuo to a solid which is stirred vigorously with 50 ml of methanol for two hours. The solid is filtered and dried to give 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-carboxaldehyde (28.7 g, 82.5%). A portion which is recrystallized from ethyl acetate has a mp of 150.5°-151.5° C.
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