The reaction of 4-fluorobenzoyl chloride (I) with N,O-dimethylhydroxylamine (II) in pyridine gives the N-methylhydroxamate (III), which is condensed with 5-bromo-1H-indole (IV) by means of KH and t-BuLi yielding the ketone (V). The alkylation of (V) with ethyl iodide and NaH in DMF affords (1-ethylindol-5-yl)(4-fluorophenyl)methanone (VI), which is reduced with NaBH4 in methanol to the corresponding carbinol (VII). Finally, this compound is treated with carbonyl diimidazole in THF.

The acylation of indole (I) with 4-fluorobenzoyl chloride (II) by means of AlCl3 in dichloromethane gives 3-(4-fluorobenzoyl)indole (III), which is N-alkylated with ethyl iodide and K2CO3 in acetone yielding 1-ethyl-3-(4-fluorobenzoyl)indole (IV). The reduction of (IV) with NaBH4 in methanol affords the corresponding carbinol (V), which is finally treated with carbonyl diimidazole (VI) in THF.

The methylation of 5-bromo-1H-indole (I) with methyl iodide and NaH in DMSO gives the 1-methyl derivative (II), which is acylated with 4-fluorobenzoyl chloride (III) and AlCl3 in dichloromethane yielding the 3-acyl derivative (IV). The reduction of (IV) with NaBH4 in methanol affords the corresponding carbinol (V), which is finally treated with carbonyl diimidazole (VI) in THF.