合成路线1

Condensation between 4-fluorophenylhydrazine (I) and 2-ketoglutaric acid (II) produced the intermediate hydrazone (III), which was cyclized and esterified to the indole diester (IV) under Fischer synthesis conditions. Alkylation of the indole nitrogen with iodomethane and NaH produced the N-methyl indole (V). This was condensed with dimethylformamide-dimethylacetal in refluxing DMF to furnish the enamino ester (VI). Condensation of enamine (VI) with aniline (VII), followed by cyclization of the intermediate enamino ester under basic conditions, gave rise to the pyridoindole (VIII). The remaining ester group of (VIII) was then hydrolyzed with NaOH to the corresponding carboxylic acid (IX), which was finally coupled with pyrrolidine (X) via activation with carbonyldiimidazole.