Together with the Boger lab we recently published our work "Mechanistic Insights into the Reaction of Amidines with 1,2,3-Triazines and 1,2,3,5-Tetrazines" in JACS. In this paper we investigate the mechanism of these cycloadditions using experimental (kinetic experiments, KIE, isotope labeling) and computational methods. We could show that these reactions proceed through an addition/elimination/electrocyclization mechanism. Find the open access paper here: https://pubs.acs.org/doi/full/10.1021/jacs.2c03726