A Convergent Hybrid Gram-Scale Synthesis of Tirzepatide: Tangential Flow Filtration Assisted Native Chemical Ligation-Desulfurization Approach.

The development of scalable and efficient manufacturing of high-volume complex synthetic peptides and proteins, like tirzepatide (TZP, 1), faces major hurdles due to the limitations of traditional Solid Phase Peptide Synthesis (SPPS) and Liquid Phase Peptide Synthesis (LPPS). To enable the commercial synthesis of tirzepatide, we pioneered an innovative four-fragment convergent hybrid SPPS/LPPS strategy combining their individual strengths. Integrating advanced techniques, like flow chemistry for fragment condensation and nanofiltration for intermediate purification, ensures high efficiency and scalability, setting a new standard for large-scale production. Given the broader reliance on inefficient linear SPPS in the field, our work underscores the potential of hybrid synthesis strategies to transform peptide manufacturing. The convergent approach allows for the simultaneous synthesis of high purity peptide fragments, significantly reducing overall manufacturing time and increasing API throughput. Concurrently, we established a two-fragment route leveraging Native Chemical Ligation (NCL) followed by tandem desulfurization. This method achieves the chemoselective coupling of unprotected peptide fragments in aqueous media, without epimerization. Crucially, we employed tangential flow filtration (TFF) to effectively purify intermediates between ligation and desulfurization, circumventing solvent-intensive steps. This NCL/TFF combination offers a powerful, orthogonal, and greener path to TZP, representing a meaningful innovation in synthetic peptide process chemistry.