Total synthesis of (±)-Gelsemoxonine

Area of Science:

• Organic Chemistry
• Natural Product Synthesis
• Medicinal Chemistry

Background:

• Gelsemoxonine is a Gelsemium alkaloid featuring a complex structure with an unusual azetidine ring.
• The synthesis of complex natural products is crucial for understanding their biological activity and for developing new therapeutic agents.

Purpose of the Study:

• To achieve the first total synthesis of Gelsemoxonine.
• To develop novel synthetic methodologies applicable to complex alkaloid structures.

Main Methods:

• A novel ring contraction of a spirocyclopropane isoxazolidine to generate a key beta-lactam intermediate.
• Elaboration of the beta-lactam into the azetidine core of Gelsemoxonine.
• Highly diastereoselective reductive Heck cyclization for oxindole ring system construction.
• Directed hydrosilylation of an alkyne to install the ethyl ketone moiety.

Main Results:

• Successful and efficient total synthesis of Gelsemoxonine.
• Demonstration of a novel spirocyclopropane isoxazolidine ring contraction strategy.
• Application of a highly diastereoselective reductive Heck cyclization in natural product synthesis.
• Establishment of a directed hydrosilylation method for ketone installation.

Conclusions:

• The developed synthetic route provides a viable pathway to Gelsemoxonine and related Gelsemium alkaloids.
• The novel methodologies employed can be valuable for the synthesis of other complex nitrogen-containing heterocycles.
• This synthesis lays the groundwork for further biological evaluation of Gelsemoxonine and its analogs.