Advancing Peptide Synthesis: Liquid-Phase Assembly of Tirzepatide’s C-Terminus (30–39) via Crystalline Pentamer Building Blocks

Traditional solid-phase peptide synthesis (SPPS) is limited in its suitability for high-volume peptide/protein manufacturing applications due to its reliance on specialized equipment, high process mass intensity (PMI), and the use of environmentally concerning reagents. To address these limitations, a fully liquid-phase peptide synthesis (LPPS) has been developed and applied to the synthesis of a tirzepatide (30–39) fragment intermediate. This method leverages Fmoc- and Cbz-protecting group strategies to generate two high-purity crystalline pentamers entirely without solid-phase techniques. Subsequent solution-phase assembly of the pentamers yields the desired decapeptide. This green, efficient, and practical route offers a more economical and environmentally favorable alternative to SPPS, delivering a fragment intermediate of superior quality. Additionally, tirzepatide (30–39) decapeptide is a potential common intermediate for numerous other incretin peptides using hybrid SPPS/LPPS methodologies.