Figure 1.
The tetrazine ligation with trans-cyclooctenes serves as a rapid method for the assembly of biomolecular-probe constructs. (A) The first generation system for F-18 labeling proceeds with fast kinetics but the Diels-Alder conjugate displays poor metabolic stability. (B) Diels-Alder conjugate from 1 and diphenyl-s-tetrazine derivative 3 displays improved metabolic stability. (C) The conformationally strained sTCO is the most reactive dienophile described to date, with rate constants of up to 3.3. x 106 M-1s-1 for room temperature conjugations in water.