合成路线1

Keto ester (III) was prepared by Friedel-Crafts acylation of 2-fluorobiphenyl (I) with methyl glutaryl chloride (II). Subsequent Pfitzinger condensation of (III) with 5-fluoroisatin (IV) furnished the quinoline derivative (V). Chlorination of diacid (V) with SOCl2, followed by treatment with methanol produced selectively the mono-ester (VI). The remaining carboxyl group of (VI) was activated with SOCl2 in the presence of DMF, and subsequently coupled with n-octyl amine to generate amide (VII). The methyl ester group of (VII) was then hydrolyzed to acid (VIII), which was further subjected to intramolecular ring closure upon heating with triflic acid to afford the tetracyclic system (IX). Keto group reduction in (IX) to give (X) was accomplished by a two-step procedure with NaBH4 and then with HI and Ac2O.