TCO-NHS Ester (axial)
TCO-NHS Ester is an amine-reactive building block used for modification of amine-containing molecule in organic media. TCO-NHS ester is supplied as a single axial (minor, rel-(1S-2S-5E-pS), ref 1 and 4) diastereomer. Specially formulated crystalline provides easy handling and extended shelf life.
Axial TCO derivatives demonstrate much higher reactivity in the inverse electron demand cycloaddition reaction compared to equatorial TCO derivatives. Up to 10-fold increase in reactivity was reported (ref 4) compared to equatorial TCO derivatives. At the same time, the axial TCO derivatives undergo cis-trans deactivation at faster rate compared to equatorial TCO derivatives (ref 4).
1. Royzen, M., et al. (2008). A Photochemical Synthesis of Functionalized trans-Cyclooctenes Driven by Metal Complexation. J. AM. CHEM. SOC., 130: 3760-1. [PubMed]
2. Blackman, M.L., et al. (2008). Tetrazine ligation: fast bioconjugation based on inverse-electron-demand Diels-Alder reactivity. J. AM. CHEM. SOC., 130: 13518-9. [PubMed]
3. Rahim, M.K., et al. (2015). Enhancing Reactivity for Bioorthogonal Pretargeting by Unmasking Antibody-Conjugated trans-Cyclooctenes. Bioconjugate Chem., 26: 352-60. [PubMed]
4. Rossin, R., et al. (2013). Highly Reactive trans-Cyclooctene Tags with Improved Stability for Diels−Alder Chemistry in Living Systems. Bioconjugate Chem., 24: 1210-7. [PubMed]