HMDO-Promoted Peptide and Protein Synthesis in Ionic Liquids

In situ generation of acyloxyphosphoniums for mild and efficient synthesis of thioesters

We present a novel approach for in situ generation of acyloxyphosphoniums by premixing iodobenzene dicarboxylates and triphenylphosphine, resulting in efficient thioester synthesis (up to 100% yield). Stable solid iodobenzene dicarboxylates, achieved via carboxylate exchange, serve as hypervalent iodine precursors. The resulting acyloxyphosphoniums allow convenient one-pot thioester synthesis under mild conditions. Our method demonstrates facile acyloxyphosphonium production from iodobenzene dicarboxylates and Ph3P, enabling diverse thioester preparation. ESI-MS analysis confirms acyloxyphosphonium ion formation, pivotal in acylation. This strategy holds potential for combinatorial thioester synthesis and broader nucleophile modification applications.

Native Chemical Ligation of Highly Hydrophobic Peptides in Ionic Liquid-Containing Media

The chemical synthesis of a highly hydrophobic membrane-associated peptide by native chemical ligation (NCL) in an ionic liquid (IL) [C₂mim][OAc]/buffer mixture was achieved by employing peptide concentrations up to 11 mM. NCL was studied at different pH and water content and compared to several “gold-standard” ligation protocols. The optimized reaction protocol for the NCL in IL required the addition of 40% water and pH adjustment to 7.0–7.5, resulting in ligation yields of up to 80–95% within 1 to 4 h. This new ligation protocol is generally applicable and outperforms current “gold-standard” NCL methods.

Facile Cu(ii)-mediated conjugation of thioesters and thioacids to peptides and proteins under mild conditions

The bioconjugation of peptide derivatives such as polypeptides, peptide-based probes and proteins is a vibrant area in many scientific fields. However, reports on metal-mediated chemical methods towards native peptides especially non-engineering protein modification under mild conditions are still limited. Herein, we describe a novel Cu(ii)-mediated strategy for the conjugation of thioesters/thioacids to peptides under mild conditions with high functional group tolerance. Based on this strategy, polypeptides, even peptide-based fluorescent probes, can be efficiently constructed. Finally, the selective modification of lysine residues of native Ub with thioesters could be realized and complete conjugation of Ub could be achieved even under equivalent Cu(ii). These promising results could greatly expand Cu(ii)-mediated reaction strategies on chemical biology and molecular imaging.

Catalyst-free amidation of aldehyde with amine under mild conditions

A highly efficient, catalyst-free and one-pot procedure for the direct synthesis of amides from aldehydes and amines under mild conditions has been developed.

Ionic liquid-supported synthesis of piperazine derivatives as potential insecticides

With the purpose of extending our efforts on the search and synthesis of new insecticides with novel acting modes, a series of novel 4-(2-(4-(pyridin-2-yl)piperazin-1-yl)ethoxy)aniline derivatives were designed based on classical serotonin receptor ligands and synthesized through the rapid ionic liquid-supported parallel synthesis with yields up to 88 %. These products were purified through the convenient washing with appropriate solvents and isolated in good yield. In addition, 27 amide or urea derivatives of anilines were also prepared. Bioassay data showed that some of the synthesized compounds displayed selective insecticidal bioactivities against tested pests.