Total Synthesis of Ansellone G and Phorbadione

The first total synthesis of marine sesterterpenoid ansellone G (2) was accomplished. This strategy utilizes the Prins cyclization reaction of a chloro-substituted homoallyl alcohol to synthesize the hydrobenzopyran skeleton. The preintroduction of the chloro groups facilitated the functional group transformation for 2 after constructing the carbon framework. Furthermore, we also successfully synthesized phorbadione (3) by dehydrating the tertiary alcohol. The HIV latency-reversing activity of the synthesized 2, 3, and deacetylated 2 was also evaluated. O OH HO,. * O CI Prins cyclization reaction with chloro-substituted homoallyl alcohol Prins cyclization H phorbadione (3) OAc 7.2% in 11 steps (LLS) OAc ansellone G (2) 13% in 10 steps (LLS)