Treatment of quinoline (I) with ethynylmagnesium bromide (II) in THF at low temperature, and then with 4-chlorophenyl chloroformate (III) gave carbamate (IV). Subsequent deprotection of tert-butyldimethylsilyl group with p-toluenesulfonic acid yielded allyl alcohol (V), and this was stereoselectively epoxidized with m-chloroperbenzoic acid to give epoxyalcohol (VI). Coupling of (VI) with vinyl chloride (VII) in the presence of Pd(0)-CuI catalyst provided the enediyne compound (VIII). This was oxidized with Dess-Martin periodinane reagent to the aldehyde (IX). Finally, CsF-promoted cyclization in the presence of acetic anhydride provided the title compound as a 2:1 mixture of diastereoisomers, which could not be separated.

Compound (I) as a 2:1 mixture of diastereoisomers was hydrolyzed with barium hydroxide to afford a mixture of alcohols (II). Further reaction with thiocarbonyldiimidazole (III) and dimethylamino-pyridine (DMAP) gave thiocarbamate (IV), which was finally reduced with tributyltin hydride and azabis(isobutyronitrile) (AIBN) in refluxing benzene.