Dual Benefits For Big Rings

J. Am. Chem. Soc. View Enlarged Image

A bifunctional building block packs a one-two punch for making the ring-shaped molecules known as macrocycles, chemists at the University of Toronto have found. The reagent, an aziridine aldehyde, gets around the need to use dilute reaction conditions, which plague chemists making macrocycles. The aldehyde also provides a handle for further structural fine-tuning.

Macrocycles have desirable properties and potential as nanomaterials, imaging agents, and drugs. When making macrocycles, dilute conditions are the norm because they prevent competing reactions, but they also cause reactions to run slowly, among other disadvantages. In contrast, Ryan Hili, Vishal Rai, and Andrei K. Yudin's new macrocyclization works at unusually high concentrations.

The reaction links the team's aldehyde, an isocyanide, and the amine and carboxylic acid from the ends of a peptide without forming by-products (J. Am. Chem. Soc., DOI: 10.1021/ja910544p). The team plans to extend the reaction to a range of macrocycles beyond cyclic peptides, Yudin says.

The cyclic products have an aziridine handle for further tagging and could be screened to find new materials and therapeutics, says University of Pittsburgh organic chemist Peter Wipf. "This strategy will find many applications in medicinal and bioorganic chemistry," he says.

The Toronto team's cyclization process is "intriguing and creative," and it generates molecules reminiscent of natural cyclic peptides that have interesting bioactivities, such as cyclosporin, which has immune suppression properties, adds Samuel H. Gellman, who studies natural and unnatural peptides at the University of Wisconsin, Madison.

Chemical & Engineering News

ISSN 0009-2347

Copyright © 2011 American Chemical Society