Inverse electron demand Diels–Alder reactions of some nitrobenzofurazane–tetrazine dyes

In this thesis study, two NBD-Tz compounds were successfully synthesized via SNAr reaction using commercially available aminotetrazines (aminoTzH•HCl and aminoTzMe•HCl) and the NBD-F amine-reactive profluorophore. The synthesized compounds were thoroughly characterized using NMR spectroscopy and HRMS analysis. It was determined that the NBD-Tz compounds did not exhibit fluorescence emission in DCM solutions but gained yellow-orange fluorescence properties upon the addition of the strained dienophile exo-norbornene-2-methanol (Nb). HRMS analysis confirmed that this reaction produced cycloaddition products with a dihydropyridazine structure. The use of commercially accessible SNAr reactants and the Nb dienophile simplified the synthesis of NBD-Tz compounds. Furthermore, the rapid execution of the TETDA reaction, particularly with H-terminal NBD-Tz, demonstrates its potential to make such methods in bioorthogonal chemistry more accessible to a broader research community.