Callipeltosides A, B and C: Total Syntheses and Structural Confirmation.

Area of Science:

• Organic Chemistry
• Natural Product Synthesis
• Medicinal Chemistry

Background:

• Callipeltosides are natural products of significant interest due to their unique structures and biological activities.
• Previous synthetic efforts have been challenged by the complexity of the callipeltoside scaffold.
• Understanding the structure-activity relationship requires access to pure synthetic analogues.

Purpose of the Study:

• To present a comprehensive synthetic strategy for the callipeltoside family.
• To confirm the structural assignment of callipeltoside B through total synthesis.
• To explore the synthesis of D-configured callipeltose B.

Main Methods:

• Gold(III)-catalyzed cyclization for the C1-C9 pyran core synthesis.
• Bidirectional Stille reactions for the C10-C22 vinyl iodide fragment construction.
• Alkenylzinc addition for diastereoselective fragment coupling.

Main Results:

• Successful synthesis of the common callipeltoside aglycon.
• Assembly of the complete callipeltoside family by appending three sugar fragments.
• Synthesis of D-configured callipeltose B, with distinct NMR data supporting structural assignment of callipeltoside B.

Conclusions:

• The developed synthetic route provides efficient access to the callipeltoside family.
• The synthesis validates the proposed structure of callipeltoside B.
• This work facilitates further investigation into the biological properties of callipeltosides.