Presentation Title

Progress Towards the Total Synthesis of Pandalisines A and B

Faculty Mentor

Jonah Chang

Start Date

23-11-2019 10:00 AM

End Date

23-11-2019 10:45 AM

Location

255

Session

poster 3

Type of Presentation

Poster

Subject Area

physical_mathematical_sciences

Abstract

Pandalisines A and B are two alkaloids that were isolated in 2015 by Wu and coworkers from Pandanus utilis, the common screwpine. Alkaloids are nitrogen-containing molecules that are ubiquitous in the natural world, and many alkaloids and their derivatives are drugs that are employed in modern medicine. Pandalisines A and B are unique because they contain an indolizidine core, and yet are the first molecules possessing this moiety that are not cytotoxic. It is our hope that as we undertake the total synthesis of this molecule, we might provide significant quantities of Pandalisines A and B that will help elucidate why an indolizidine core is non-toxic in this instance. It is hoped that strategies towards Pandalisines A and B might be relevant towards future synthesis of structurally similar alkaloids, some of which that may be of medical interest. Our strategy is based on an N-acyliminium cyclization. A novel aspect of our approach is that we are intercepting the N-acyliminium intermediate with an enol lactone. Several routes toward our advanced enol lactone intermediate are presented including 1) a Sonogashira / oxidation / silver-mediated cyclization sequence and 2) a palladium-catalyzed tandem Sonogashira/lactonization reaction. In addition, preliminary results on N-acyliminium cyclization will also be presented. Future work involving the completion of the synthesis by chemoselective reduction of an amide over a lactone as well as isomerization to Pandalisine B will also be discussed.

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Nov 23rd, 10:00 AM Nov 23rd, 10:45 AM

Progress Towards the Total Synthesis of Pandalisines A and B

255

Pandalisines A and B are two alkaloids that were isolated in 2015 by Wu and coworkers from Pandanus utilis, the common screwpine. Alkaloids are nitrogen-containing molecules that are ubiquitous in the natural world, and many alkaloids and their derivatives are drugs that are employed in modern medicine. Pandalisines A and B are unique because they contain an indolizidine core, and yet are the first molecules possessing this moiety that are not cytotoxic. It is our hope that as we undertake the total synthesis of this molecule, we might provide significant quantities of Pandalisines A and B that will help elucidate why an indolizidine core is non-toxic in this instance. It is hoped that strategies towards Pandalisines A and B might be relevant towards future synthesis of structurally similar alkaloids, some of which that may be of medical interest. Our strategy is based on an N-acyliminium cyclization. A novel aspect of our approach is that we are intercepting the N-acyliminium intermediate with an enol lactone. Several routes toward our advanced enol lactone intermediate are presented including 1) a Sonogashira / oxidation / silver-mediated cyclization sequence and 2) a palladium-catalyzed tandem Sonogashira/lactonization reaction. In addition, preliminary results on N-acyliminium cyclization will also be presented. Future work involving the completion of the synthesis by chemoselective reduction of an amide over a lactone as well as isomerization to Pandalisine B will also be discussed.