Solid-phase synthesis and structural characterization of highly substituted hydroxyproline-based...

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Synthetic Chemistry

Background:

• 2,5-diketopiperazines (DKPs) are privileged heterocyclic scaffolds.
• Incorporating trans-4-hydroxy-L-proline (Hyp) offers unique structural features.
• Novel synthetic routes are needed to access diverse DKP libraries.

Purpose of the Study:

• To develop general solid-phase synthesis methods for novel DKPs.
• To introduce molecular diversity at multiple positions of the DKP scaffold.
• To explore the application of these DKPs as potential enzyme inhibitors.

Main Methods:

• Solid-phase synthesis utilizing Ellman resin.
• N-protection and methyl esterification of hydroxyproline.
• Sequential reactions including Hyp alkylation, N-acylation, cyclization, and amide bond alkylation.

Main Results:

• Successful synthesis of highly functionalized bicyclic DKPs.
• Introduction of up to three centers of molecular diversity.
• Observation of epimerization during backbone amide bond alkylation.
• Elucidation of DKP structures using multidimensional NMR.

Conclusions:

• Developed versatile solid-phase strategies for DKP synthesis.
• Demonstrated the potential for generating diverse heterocyclic compounds.
• Highlighted the applicability of these methods for discovering enzyme inhibitors.