PyAOP ((7-azabenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate) is a reagent used to prepare amides from carboxylic acids and amines in the context of peptide synthesis. It can be prepared from 1-hydroxy-7-azabenzotriazole (HOAt) and a chlorophosphonium reagent under basic conditions. It is a derivative of the HOAt family of amide bond forming reagents. It is preferred over HATU, because it does not engage in side reactions with the N-terminus of the peptide. Compared to the HOBt-containing analog PyBOP, PyAOP is more reactive due to the additional nitrogen in the fused pyridine ring of the HOAt moiety. Thermal hazard analysis by differential scanning calorimetry (DSC) shows PyAOP is potentially explosive.
↑Albericio, F.; Cases, M.; Alsina, J.; Triolo, S. A.; Carpino, L. A; Kates, S. (1997). "On the use of PyAOP, a phosphonium salt derived from HOAt, in solid-phase peptide synthesis". Tetrahedron Letters. 38 (27): 4853–4856. doi:10.1016/S0040-4039(97)01011-3.
↑Albericio, Fernando; Bofill, Josep M.; El-Faham, Ayman; Kates, Steven A. (1998). "Use of Onium Salt-Based Coupling Reagents in Peptide Synthesis1". The Journal of Organic Chemistry. 63 (26). American Chemical Society: 9678–9683. doi:10.1021/jo980807y. ISSN0022-3263.