peptides (VBXs 3q and 3r). Lower efficiency was observed on angiotensin II (1s), as well as on bigger amyloid β-proteins 1t and 1u, with however still high chemoselectivity towards the tyrosine residue (VBXs 3s, 3t and 3u). The cyclopentapeptide RGD (1v), containing an Arg-Gly-Asp motif and commonly used in targeted therapy for its property to bind specifically to integrin receptor on cell surface, was successfully labelled to give VBX 3v in 76% yield. Jagaricin (1w) is a cyclic lipopeptide natural product with promising antifungal properties. Despite the diversity of chemical structures present including threonine, histidine, glutamine and sensitive dehydrothreonine units, Jagaricin (1w) was selectively labelled on the tyrosine residue with EBX 2a in 61% HPLC-MS yield and could be isolated in 30% yield (3wa). 28