Fmoc synthesis of peptide thioesters without post-chain-assembly manipulation

Area of Science:

• Organic Chemistry
• Biochemistry
• Synthetic Chemistry

Background:

• Peptide thioesters are crucial intermediates in chemical biology and peptide synthesis.
• Existing methods for thioester synthesis can be complex and require multiple steps.

Purpose of the Study:

• To develop an operationally simple and efficient method for synthesizing peptide thioesters.
• To utilize standard Fmoc solid-phase peptide synthesis (SPPS) procedures for thioester formation.

Main Methods:

• Employing a premade enamide-containing amino acid in Fmoc-SPPS.
• Utilizing trifluoroacetic acid (TFA) for final cleavage and simultaneous thioester formation.
• Leveraging an irreversible intramolecular N-to-S acyl transfer mechanism.

Main Results:

• Successful synthesis of peptide thioesters using the developed method.
• Demonstration of the method's operational simplicity and efficiency.
• Confirmation of the intramolecular N-to-S acyl transfer as the key reaction.

Conclusions:

• The developed method offers a straightforward and effective route to peptide thioesters.
• This approach integrates seamlessly with established Fmoc-SPPS protocols.
• The use of enamide-containing amino acids provides a robust strategy for thioester synthesis.