Asymmetric Total Synthesis of (+)-Spiroapplanatumine G

Area of Science:

• Organic Chemistry
• Natural Product Synthesis
• Medicinal Chemistry

Background:

• Spiroapplanatumine G is a complex spiro-meroterpenoid featuring a unique 6/5/7 tricyclic spirobenzofuran-3-one core.
• The intricate structure of spiroapplanatumine G presents significant synthetic challenges.

Purpose of the Study:

• To achieve the first enantioselective total synthesis of spiroapplanatumine G.
• To develop efficient synthetic strategies for constructing complex spirocyclic natural products.

Main Methods:

• Enantioselective Diels-Alder reaction between an aurone ester and a silyloxydiene to establish the spirobenzofuranone core.
• Cyclopropanation followed by FeCl3-mediated oxidative ring expansion to construct the tricyclic framework.

Main Results:

• Successful enantioselective total synthesis of spiroapplanatumine G.
• The key Diels-Alder reaction efficiently created two contiguous stereogenic centers in one step.
• The developed methodology provides a viable route to spirobenzofuranone derivatives.

Conclusions:

• The reported synthesis represents a significant advancement in the total synthesis of complex natural products.
• This work provides a robust and enantioselective strategy for accessing spiro-meroterpenoids.
• The synthetic route offers potential for further exploration of spiroapplanatumine G analogs.