Synthesis and Structural Confirmation of Secalosides A and B

Area of Science:

• Natural Product Chemistry
• Organic Synthesis
• Cancer Biology

Background:

• Secalosides A and B are glycosides from rye pollen (Secale cereale) with demonstrated in vivo anticancer activity.
• Their proposed immunomodulatory mechanism of action has been hindered by ambiguous 3D structures for nearly three decades.

Purpose of the Study:

• To definitively determine the three-dimensional chemical structures of secalosides A and B.
• To establish a synthetic route for these complex molecules to facilitate further biological investigation.

Main Methods:

• Total synthesis of secalosides A and B.
• Development of a novel late-stage ring contraction strategy.
• Utilized an unprecedented transannular oxidative enolate coupling for constructing the indane core and ten-membered bis-lactone.

Main Results:

• Achieved the definitive structural elucidation of secalosides A and B.
• Successfully synthesized the complex molecules, including the highly strained ten-membered bis-lactone and indane core.
• Established a novel synthetic methodology involving transannular oxidative enolate coupling.

Conclusions:

• The total synthesis provides unambiguous structural confirmation of secalosides A and B.
• The developed synthetic route and structural assignment lay the groundwork for future studies on their anticancer mechanisms and structure-activity relationships.