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.[1] It can be prepared from 1-hydroxy-7-azabenzotriazole (HOAt) and a chlorophosphonium reagent under basic conditions.[2] 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.[3] 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.[4] Thermal hazard analysis by differential scanning calorimetry (DSC) shows PyAOP is potentially explosive.[5]
^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.