Total Synthesis\nof Artapilosine A and Artapilosine\nB

Artapilosines\nA and B, isolated from <i>Artabotrys\npilosus</i>, demonstrated significant anti-HIV reverse transcriptase\nactivity.\nIn this work, we present the first asymmetric total synthesis of (−)-artapilosine\nA and of its enantiomer (+)-artapilosine A, achieved in 10 steps with\noverall yields of 0.9% and 0.7%, respectively, starting from commercially\navailable piperonylic acid. The key step in this synthesis involved\na pivotal photocyclization reaction, providing an efficient protocol\nfor constructing the phenanthrene ring system common to many natural\nproducts. Additionally, using the same photocyclization strategy,\nwe successfully synthesized artapilosine B in 10 steps with an overall\nyield of 2.1%.