Mild reactionc onditions are highly desirable for bio-orthogonal side chain derivatizations of amino acids, peptides or proteins due to the sensitivity of these substrates. Transition metal catalysed cross-couplingss uch as Suzuki-Miyaura reactions are highly versatile, but usually require unfavourable reaction conditions, in particular,w hen applied with aryl bromides. Ligand-free solvent-stabilised Pd-nanoparticles represent an efficient and sustainable alternative to conventional phosphine-based catalysts,b ecause the cross-coupling can be performed at considerably lower temperature. We report on the applicationo fs uch ah ighly reactive heterogeneousc atalystf or the Suzuki-Miyaura cross-coupling of brominated tryptophan derivatives. The solvent-stabilised Pd-nanoparticles are even more efficient than the literature-known ADHP-Pd precatalyst. Interestingly, the latter also leads to the formation of quasi-homogeneous Pd-nanoparticles as the catalytic species. One advantage of our approach is the compatibilityw ith aqueousa nd aerobic conditions at near-ambient temperatures and short reaction times of only 2h.T he influence of different N a-protecting groups,b oronic acids as well as the impact of different amino acid side chainsi nb romotryptophan-containing peptides has been studied.N otably,asurprising acceleration of the catalysis was observed when palladium-coordinating side chainsw ere presenti np roximal positions.