合成路线1

2-Chloro-4-propionylpyridine (I) was protected as the cyclic ketal (II) with 1,3-propanediol and p-toluenesulfonic acid in refluxing toluene with azeotropical removal of water. Subsequent halogen displacement in (II) with sodium methoxide in boiling acetonitrile gave methoxypyridine (III). Lithiation of (III) with mesityllithium, followed by condensation with dimethylformamide provided formylpyridine (IV), which was reduced to alcohol (V) using NaBH4 in MeOH. The hydroxyl group of (V) was protected as the benzyl ether (VI), and the ketal group was then hydrolyzed to ketone (VII) with aqueous trifluoroacetic acid. Reformatskii reaction of (VII) with tert-butyl bromoacetate and zinc afforded the beta-hydroxyester (VIII). Further hydrogenolysis of benzyl ether of (VIII) over Pd/C gave alcohol (IX). Then, treatment of (IX) with trifluoroacetic acid produced lactone (X), and hydrolysis of the methoxy group of (X) with aqueous HCl furnished pyridone (XI). Condensation of 3,4-difluoroacetanilide (XII) with Vilsmeier reagent yielded quinolinecarboxaldehyde (XIII), which was reduced to alcohol (XIV) with NaBH4. This was then coupled with pyridone (XI) under Mitsunobu conditions to give (XV). Finally, Heck reaction of (XV) with palladium acetate and triphenyl phosphine generated the target pentacyclic compound.