Comparative Evaluation of Alternative Deblocking Agents to Piperidine for Solid-Phase Synthesis of Peptides

The availability of piperidine, which is widely used for deblocking α-amine groups in solid-phase peptide synthesis using Fmoc methodology, is now significantly limited because this reagent is classified as a controlled substance. Therefore, a search for other available reagents capable of removing Fmoc-protection seems relevant. The suitability of three deblocking reagents based on secondary amines (4-methylpiperidine, pyrrolidine, and piperazine) for the solid-phase synthesis of peptides of various structures, i.e., atosiban (an analog of the neurohypophysial hormone oxytocin), metilin [an agonist of the apelin receptor (APJ)], and a fragment of the 11-19 amino-acid segment of the regulatory myosin light chain was comparatively assessed. These reagents were shown to be suitable alternatives to piperidine for the preparation of the physiologically active peptides being studied.