Succinimidyl ester functionalized tetrazine for inverse electron demand Diels-Alder cycloaddition reactions. Succinimidyl ester will react with amines for small molecule, biomolecule or surface modification. Tetrazine will react with strained alkenes such as transcyclooctene, norbornene and cyclopropene to yield a stable covalent linkage. Tetrazines have proven useful in bioorthogonal reactions for many biological imaging and bioconjugation applications.