A novel and efficient synthesis of cyclopropyl peptidomimetics has been previously reported by our group, using protected amino acids as starting materials. The key step is cyclopropanation of an amino acid-derived enone to afford cyclopropyl peptidomimetics. However, this step suffered from a lack of stereoselectivity, producing both syn and anti diastereomers in equal amounts. Investigation and application of the use of quinine and quinidine ethers as catalysts in this Michael-induced ring closure step has greatly enhanced the stereoselectivity. The methyl ether of quinine affords the syn diastereomer selectively, but only for enones with an alpha-branched substituent, such as the valine-derived enone. However, the quinine benzyl ether is selective for the syn diastereomer in all cases. The pseudoenantiomer quinidine benzyl ether is selective for the anti diastereomer in all cases. Results will be presented for seven different enones, with both catalysts.

Stereoselective cyclopropanation of amino acid-derived enones using cinchona alkaloids

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.