Used in bioorthogonal chemistry for site-specific protein and peptide modifications. Enables selective labeling of biomolecules in complex biological environments without interfering with native biochemical processes. Commonly applied in live-cell imaging, targeted drug delivery, and development of antibody-drug conjugates. The trifluoroacetyl group acts as a masked amine, allowing for controlled deprotection and subsequent conjugation. Ideal for sequential labeling strategies due to its stability and selective reactivity with nucleophiles under mild conditions.