合成路线1

The title compound is prepared starting from artemisinic acid (I), which is extracted from the leaves of Artemisia annua. Esterification of (I) with ethereal diazomethane affords methyl ester (II). Reduction of (II) by means of lithium or sodium borohydride and NiCl2 leads to the saturated ester (III), which is further reduced with DIBAL to the aldehyde (IV). Condensation of (IV) with the sulfur ylide generated from trimethylsulfonium iodide and KOH furnishes epoxide (V). Then, epoxide ring opening with the Grignard reagent (VI) gives alcohol (VII). Photooxigenative cyclization of (VII) produces the artemisinin derivative (VIII). Finally, oxidative vinyl group cleavage employing KMnO4 yields the target carboxylic acid. (1,2)